Update README

This commit adds a documentation file with detailed instructions for how
to use the module properly.

.github/workflows/ci.yml

@@ -703,8 +703,8 @@ jobs:
           - { WIDEMUL: 'int128',                  ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
           - { WIDEMUL: 'int128', RECOVERY: 'yes' }
           - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes' }
-          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', CC: 'gcc' }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', CC: 'gcc', FROST: 'yes' }
-          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes',           WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
+          - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
           - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', CC: 'gcc', WRAPPER_CMD: 'valgrind --error-exitcode=42', SECP256K1_TEST_ITERS: 2 }
           - { WIDEMUL: 'int128', RECOVERY: 'yes', ECDH: 'yes', SCHNORRSIG: 'yes', ELLSWIFT: 'yes', EXPERIMENTAL: 'yes', ECDSA_S2C: 'yes', RANGEPROOF: 'yes', WHITELIST: 'yes', GENERATOR: 'yes', MUSIG: 'yes', ECDSAADAPTOR: 'yes', BPPP: 'yes', SCHNORRSIG_HALFAGG: 'yes', FROST: 'yes', CPPFLAGS: '-DVERIFY', CTIMETESTS: 'no' }
           - BUILD: 'distcheck'

.gitignore

@@ -72,3 +72,4 @@ frost_example
 /CMakeUserPresets.json
 # Default CMake build directory.
 /build
+xconfigure.sh

README.md

@@ -3,7 +3,7 @@ libsecp256k1-zkp
 
 ![Dependencies: None](https://img.shields.io/badge/dependencies-none-success)
 
-A fork of [libsecp256k1](https://github.com/bitcoin-core/secp256k1) with support for advanced and experimental features such as Confidential Assets and MuSig2 
+A fork of [libsecp256k1](https://github.com/bitcoin-core/secp256k1) with support for advanced and experimental features such as Confidential Assets, MuSig2, and FROST. 
 
 Added features:
 * Experimental module for ECDSA adaptor signatures.
@@ -12,7 +12,7 @@ Added features:
 * Experimental module for Confidential Assets (Pedersen commitments, range proofs, and [surjection proofs](src/modules/surjection/surjection.md)).
 * Experimental module for Bulletproofs++ range proofs.
 * Experimental module for [address whitelisting](src/modules/whitelist/whitelist.md).
-* Experimental module for FROST.
+* Experimental module for [FROST](src/modules/frost/frost.md).
 
 Experimental features are made available for testing and review by the community. The APIs of these features should not be considered stable.
 

ci/ci.sh

@@ -14,8 +14,8 @@ print_environment() {
     for var in WERROR_CFLAGS MAKEFLAGS BUILD \
             ECMULTWINDOW ECMULTGENPRECISION ASM WIDEMUL WITH_VALGRIND EXTRAFLAGS \
             EXPERIMENTAL ECDH RECOVERY SCHNORRSIG SCHNORRSIG_HALFAGG ELLSWIFT \
-            ECDSA_S2C GENERATOR RANGEPROOF WHITELIST MUSIG ECDSAADAPTOR BPPP FROST \
+            ECDSA_S2C GENERATOR RANGEPROOF WHITELIST MUSIG ECDSAADAPTOR BPPP \
-            SECP256K1_TEST_ITERS BENCH SECP256K1_BENCH_ITERS CTIMETESTS\
+            FROST SECP256K1_TEST_ITERS BENCH SECP256K1_BENCH_ITERS CTIMETESTS\
             EXAMPLES \
             HOST WRAPPER_CMD \
             CC CFLAGS CPPFLAGS AR NM

configure.ac

@@ -236,15 +236,15 @@ AC_ARG_ENABLE(module_ecdsa-adaptor,
     [],
     [SECP_SET_DEFAULT([enable_module_ecdsa_adaptor], [no], [yes])])
 
-AC_ARG_ENABLE(module_frost,
-    AS_HELP_STRING([--enable-module-frost],[enable FROST module [default=no]]),
-    [],
-    [SECP_SET_DEFAULT([enable_module_frost], [no], [yes])])
-
 AC_ARG_ENABLE(external_default_callbacks,
     AS_HELP_STRING([--enable-external-default-callbacks],[enable external default callback functions [default=no]]), [],
     [SECP_SET_DEFAULT([enable_external_default_callbacks], [no], [no])])
 
+AC_ARG_ENABLE(module_frost,
+    AS_HELP_STRING([--enable-module-frost],[enable FROST module (experimental)]),
+    [],
+    [SECP_SET_DEFAULT([enable_module_frost], [no], [yes])])
+
 # Test-only override of the (autodetected by the C code) "widemul" setting.
 # Legal values are:
 #  * int64 (for [u]int64_t),
@@ -475,14 +475,6 @@ if test x"$enable_module_ecdsa_adaptor" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ECDSA_ADAPTOR=1"
 fi
 
-if test x"$enable_module_frost" = x"yes"; then
-  if test x"$enable_module_schnorrsig" = x"no"; then
-    AC_MSG_ERROR([Module dependency error: You have disabled the schnorrsig module explicitly, but it is required by the musig module.])
-  fi
-  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_FROST=1"
-  enable_module_schnorrsig=yes
-fi
-
 if test x"$enable_module_musig" = x"yes"; then
   if test x"$enable_module_schnorrsig" = x"no"; then
     AC_MSG_ERROR([Module dependency error: You have disabled the schnorrsig module explicitly, but it is required by the musig module.])
@@ -543,6 +535,14 @@ if test x"$enable_module_ecdh" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_ECDH=1"
 fi
 
+if test x"$enable_module_frost" = x"yes"; then
+  if test x"$enable_module_schnorrsig" = x"no"; then
+    AC_MSG_ERROR([Module dependency error: You have disabled the schnorrsig module explicitly, but it is required by the frost module.])
+  fi
+  SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DENABLE_MODULE_FROST=1"
+  enable_module_schnorrsig=yes
+fi
+
 if test x"$enable_external_default_callbacks" = x"yes"; then
   SECP_CONFIG_DEFINES="$SECP_CONFIG_DEFINES -DUSE_EXTERNAL_DEFAULT_CALLBACKS=1"
 fi
@@ -592,12 +592,12 @@ else
   if test x"$enable_module_generator" = x"yes"; then
     AC_MSG_ERROR([NUMS generator module is experimental. Use --enable-experimental to allow.])
   fi
-  if test x"$enable_module_frost" = x"yes"; then
-    AC_MSG_ERROR([FROST module is experimental. Use --enable-experimental to allow.])
-  fi
   if test x"$set_asm" = x"arm32"; then
     AC_MSG_ERROR([ARM32 assembly is experimental. Use --enable-experimental to allow.])
   fi
+  if test x"$enable_module_frost" = x"yes"; then
+    AC_MSG_ERROR([FROST module is experimental. Use --enable-experimental to allow.])
+  fi
 fi
 
 ###
@@ -666,9 +666,9 @@ echo "  module whitelist        = $enable_module_whitelist"
 echo "  module musig            = $enable_module_musig"
 echo "  module ecdsa-s2c        = $enable_module_ecdsa_s2c"
 echo "  module ecdsa-adaptor    = $enable_module_ecdsa_adaptor"
-echo "  module frost            = $enable_module_frost"
 echo "  module bppp             = $enable_module_bppp"
 echo "  module schnorrsig-halfagg = $enable_module_schnorrsig_halfagg"
+echo "  module frost            = $enable_module_frost"
 echo
 echo "  asm                       = $set_asm"
 echo "  ecmult window size        = $set_ecmult_window"

examples/frost.c

@@ -1,5 +1,5 @@
 /***********************************************************************
- * Copyright (c) 2021-2023  Jesse Posner                               *
+ * Copyright (c) 2021-2024  Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying    *
  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
  ***********************************************************************/
@@ -25,8 +25,10 @@
 #define THRESHOLD 3
 
 struct signer_secrets {
-    secp256k1_frost_share share;
+    secp256k1_keypair keypair;
+    secp256k1_frost_share agg_share;
     secp256k1_frost_secnonce secnonce;
+    unsigned char seed[32];
 };
 
 struct signer {
@@ -34,26 +36,86 @@ struct signer {
     secp256k1_frost_pubnonce pubnonce;
     secp256k1_frost_session session;
     secp256k1_frost_partial_sig partial_sig;
+    secp256k1_pubkey vss_commitment[THRESHOLD];
+    unsigned char vss_hash[32];
+    unsigned char pok[64];
+    unsigned char id[33];
 };
 
-/* Create shares and coefficient commitments */
+/* Create a key pair and store it in seckey and pubkey */
-int create_shares(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signers, secp256k1_xonly_pubkey *pk) {
+int create_keypair_and_seed(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signer) {
-    int i;
+    unsigned char seckey[32];
-    secp256k1_frost_share shares[N_SIGNERS];
+    secp256k1_pubkey pubkey_tmp;
-    secp256k1_pubkey pubshares[N_SIGNERS];
+    size_t size = 33;
-    unsigned char seed[32];
 
-    if (!fill_random(seed, sizeof(seed))) {
+    while (1) {
+        if (!fill_random(seckey, sizeof(seckey))) {
+            printf("Failed to generate randomness\n");
+            return 1;
+        }
+        if (secp256k1_keypair_create(ctx, &signer_secrets->keypair, seckey)) {
+            break;
+        }
+    }
+    if (!secp256k1_keypair_pub(ctx, &pubkey_tmp, &signer_secrets->keypair)) {
         return 0;
     }
-
+    if (!secp256k1_ec_pubkey_serialize(ctx, signer->id, &size, &pubkey_tmp, SECP256K1_EC_COMPRESSED)) {
-    if (!secp256k1_frost_shares_trusted_gen(ctx, shares, pubshares, pk, seed, THRESHOLD, N_SIGNERS)) {
         return 0;
     }
+    if (!fill_random(signer_secrets->seed, sizeof(signer_secrets->seed))) {
+        return 0;
+    }
+    return 1;
+}
+
+/* Create shares and coefficient commitments */
+int create_shares(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signer, secp256k1_xonly_pubkey *pk) {
+    int i, j;
+    secp256k1_frost_share shares[N_SIGNERS][N_SIGNERS];
+    const secp256k1_pubkey *vss_commitments[N_SIGNERS];
+    const unsigned char *ids[N_SIGNERS];
+
+    for (i = 0; i < N_SIGNERS; i++) {
+        vss_commitments[i] = signer[i].vss_commitment;
+        ids[i] = signer[i].id;
+    }
 
     for (i = 0; i < N_SIGNERS; i++) {
-        signer_secrets[i].share = shares[i];
+        /* Generate a polynomial share for the participants */
-        signers[i].pubshare = pubshares[i];
+        if (!secp256k1_frost_shares_gen(ctx, shares[i], signer[i].vss_commitment, signer[i].pok, signer_secrets[i].seed, THRESHOLD, N_SIGNERS, ids)) {
+            return 0;
+        }
+    }
+
+    /* KeyGen communication round 1: exchange shares and coefficient
+     * commitments */
+    for (i = 0; i < N_SIGNERS; i++) {
+        const secp256k1_frost_share *assigned_shares[N_SIGNERS];
+
+        /* Each participant receives a share from each participant (including
+         * themselves) corresponding to their index. */
+        for (j = 0; j < N_SIGNERS; j++) {
+            assigned_shares[j] = &shares[j][i];
+        }
+        /* Each participant aggregates the shares they received. */
+        if (!secp256k1_frost_share_agg(ctx, &signer_secrets[i].agg_share, pk, assigned_shares, vss_commitments, N_SIGNERS, THRESHOLD, signer[i].id)) {
+            return 0;
+        }
+        for (j = 0; j < N_SIGNERS; j++) {
+            /* Each participant verifies their shares. share_agg calls this
+             * internally, so it is only neccessary to call this function if
+             * share_agg returns an error, to determine which participant(s)
+             * submitted faulty data. */
+            if (!secp256k1_frost_share_verify(ctx, THRESHOLD, signer[i].id, assigned_shares[j], &vss_commitments[j])) {
+                return 0;
+            }
+            /* Each participant generates public verification shares that are
+             * used for verifying partial signatures. */
+            if (!secp256k1_frost_compute_pubshare(ctx, &signer[j].pubshare, THRESHOLD, signer[j].id, vss_commitments, N_SIGNERS)) {
+                return 0;
+            }
+        }
     }
 
     return 1;
@@ -102,16 +164,15 @@ int tweak(const secp256k1_context* ctx, secp256k1_xonly_pubkey *pk, secp256k1_fr
  * the result in sig */
 int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, struct signer *signer, const unsigned char* msg32, secp256k1_xonly_pubkey *pk, unsigned char *sig64, const secp256k1_frost_tweak_cache *cache) {
     int i;
-    size_t signer_id = 0;
+    int signer_id = 0;
     int signers[THRESHOLD];
     int is_signer[N_SIGNERS];
     const secp256k1_frost_pubnonce *pubnonces[THRESHOLD];
-    size_t ids[THRESHOLD];
+    const unsigned char *ids[THRESHOLD];
     const secp256k1_frost_partial_sig *partial_sigs[THRESHOLD];
 
     for (i = 0; i < N_SIGNERS; i++) {
         unsigned char session_id[32];
-
         /* Create random session ID. It is absolutely necessary that the session ID
          * is unique for every call of secp256k1_frost_nonce_gen. Otherwise
          * it's trivial for an attacker to extract the secret key! */
@@ -120,14 +181,14 @@ int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, st
         }
         /* Initialize session and create secret nonce for signing and public
          * nonce to send to the other signers. */
-        if (!secp256k1_frost_nonce_gen(ctx, &signer_secrets[i].secnonce, &signer[i].pubnonce, session_id, &signer_secrets[i].share, msg32, pk, NULL)) {
+        if (!secp256k1_frost_nonce_gen(ctx, &signer_secrets[i].secnonce, &signer[i].pubnonce, session_id, &signer_secrets[i].agg_share, msg32, pk, NULL)) {
             return 0;
         }
         is_signer[i] = 0; /* Initialize is_signer */
     }
     /* Select a random subset of signers */
     for (i = 0; i < THRESHOLD; i++) {
-        size_t subset_seed;
+        unsigned int subset_seed;
 
         while (1) {
             if (!fill_random((unsigned char*)&subset_seed, sizeof(subset_seed))) {
@@ -144,19 +205,19 @@ int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, st
         /* Mark signer as assigned */
         pubnonces[i] = &signer[signer_id].pubnonce;
         /* pubkeys[i] = &signer[signer_id].pubkey; */
-        ids[i] = signer_id + 1;
+        ids[i] = signer[signer_id].id;
     }
     /* Signing communication round 1: Exchange nonces */
     for (i = 0; i < THRESHOLD; i++) {
         signer_id = signers[i];
-        if (!secp256k1_frost_nonce_process(ctx, &signer[signer_id].session, pubnonces, THRESHOLD, msg32, pk, signer_id + 1, ids, cache, NULL)) {
+        if (!secp256k1_frost_nonce_process(ctx, &signer[signer_id].session, pubnonces, THRESHOLD, msg32, pk, signer[signer_id].id, ids, cache, NULL)) {
             return 0;
         }
         /* partial_sign will clear the secnonce by setting it to 0. That's because
          * you must _never_ reuse the secnonce (or use the same session_id to
          * create a secnonce). If you do, you effectively reuse the nonce and
          * leak the secret key. */
-        if (!secp256k1_frost_partial_sign(ctx, &signer[signer_id].partial_sig, &signer_secrets[signer_id].secnonce, &signer_secrets[signer_id].share, &signer[signer_id].session, cache)) {
+        if (!secp256k1_frost_partial_sign(ctx, &signer[signer_id].partial_sig, &signer_secrets[signer_id].secnonce, &signer_secrets[signer_id].agg_share, &signer[signer_id].session, cache)) {
             return 0;
         }
         partial_sigs[i] = &signer[signer_id].partial_sig;
@@ -185,6 +246,7 @@ int sign(const secp256k1_context* ctx, struct signer_secrets *signer_secrets, st
 
 int main(void) {
     secp256k1_context* ctx;
+    int i;
     struct signer_secrets signer_secrets[N_SIGNERS];
     struct signer signers[N_SIGNERS];
     secp256k1_xonly_pubkey pk;
@@ -194,6 +256,14 @@ int main(void) {
 
     /* Create a context for signing and verification */
     ctx = secp256k1_context_create(SECP256K1_CONTEXT_NONE);
+    printf("Creating key pairs......");
+    for (i = 0; i < N_SIGNERS; i++) {
+        if (!create_keypair_and_seed(ctx, &signer_secrets[i], &signers[i])) {
+            printf("FAILED\n");
+            return 1;
+        }
+    }
+    printf("ok\n");
     printf("Creating shares.........");
     if (!create_shares(ctx, signer_secrets, signers, &pk)) {
         printf("FAILED\n");
@@ -201,7 +271,7 @@ int main(void) {
     }
     printf("ok\n");
     printf("Tweaking................");
-    /* Optionally tweak the key */
+    /* Optionally tweak the aggregate key */
     if (!tweak(ctx, &pk, &cache)) {
         printf("FAILED\n");
         return 1;

include/secp256k1_frost.h

@@ -9,9 +9,9 @@ extern "C" {
 
 #include <stdint.h>
 
-/** This code is currently a work in progress. It's not secure nor stable.  IT
+/** This code is currently a work in progress. It's not secure nor stable.
- * IS EXTREMELY DANGEROUS AND RECKLESS TO USE THIS MODULE IN PRODUCTION!
+ * IT IS EXTREMELY DANGEROUS AND RECKLESS TO USE THIS MODULE IN PRODUCTION!
-
+ *
  * This module implements a variant of Flexible Round-Optimized Schnorr
  * Threshold Signatures (FROST) by Chelsea Komlo and Ian Goldberg
  * (https://crysp.uwaterloo.ca/software/frost/). Signatures are compatible with
@@ -21,6 +21,9 @@ extern "C" {
  * The module also supports BIP-341 ("Taproot") and BIP-32 ("ordinary") public
  * key tweaking, and adaptor signatures.
  *
+ * It is recommended to read the documentation in this include file carefully.
+ * Further notes on API usage can be found in src/modules/frost/frost.md
+ *
  * Following the convention used in the MuSig module, the API uses the singular
  * term "nonce" to refer to the two "nonces" used by the FROST scheme.
  */
@@ -183,11 +186,13 @@ SECP256K1_API int secp256k1_frost_share_parse(
 
 /** Creates key shares
  *
- *  To generate a key, a trusted dealer generates a share for each other
+ *  To generate a key, each participant generates a share for each other
- *  participant.
+ *  participant. For example, in the case of 2 particpants, Alice and Bob, they
+ *  each generate 2 shares, distribute 1 share to each other using a secure
+ *  channel, and keep 1 for themselves.
  *
- *  The trusted dealer must transmit shares over secure channels to
+ *  Each participant must transmit shares over secure channels to each other
- *  participants.
+ *  participant.
  *
  *  Each call to this function must have a UNIQUE and uniformly RANDOM seed32
  *  that must that must NOT BE REUSED in subsequent calls to this function and
@@ -196,25 +201,109 @@ SECP256K1_API int secp256k1_frost_share_parse(
  *  Returns: 0 if the arguments are invalid, 1 otherwise
  *  Args:            ctx: pointer to a context object
  *  Out:          shares: pointer to the key shares
- *             pubshares: pointer to the public verification shares
+ *        vss_commitment: pointer to the VSS commitment
- *                    pk: pointer to the x-only public key
+ *                 pok64: pointer to the proof of knowledge
- *   In:          seed32: a 32-byte random seed as explained above. Must be
+ *   In:          seed32: 32-byte random seed as explained above. Must be
- *                        unique to this call to
+ *                        unique to this call to secp256k1_frost_shares_gen
- *                        secp256k1_frost_shares_trusted_gen and must be
+ *                        and must be uniformly random.
- *                        uniformly random.
  *             threshold: the minimum number of signers required to produce a
  *                        signature
  *        n_participants: the total number of participants
+ *                 ids33: array of 33-byte participant IDs
  */
-SECP256K1_API int secp256k1_frost_shares_trusted_gen(
+SECP256K1_API int secp256k1_frost_shares_gen(
     const secp256k1_context *ctx,
     secp256k1_frost_share *shares,
-    secp256k1_pubkey *pubshares,
+    secp256k1_pubkey *vss_commitment,
-    secp256k1_xonly_pubkey *pk,
+    unsigned char *pok64,
     const unsigned char *seed32,
     size_t threshold,
+    size_t n_participants,
+    const unsigned char * const* ids33
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(8);
+
+/** Aggregates shares
+ *
+ *  As part of the key generation protocol, each participant receives a share
+ *  from each participant, including a share they "receive" from themselves.
+ *  This function verifies those shares against their VSS commitments,
+ *  aggregates the shares, and then aggregates the commitments to each
+ *  participant's first polynomial coefficient to derive the aggregate public
+ *  key.
+ *
+ *  If this function returns an error, `secp256k1_frost_share_verify` can be
+ *  called on each share to determine which participants submitted faulty
+ *  shares.
+ *
+ *  Returns: 0 if the arguments are invalid, 1 otherwise (which does NOT mean
+ *           the resulting signature verifies).
+ *  Args:         ctx: pointer to a context object
+ *  Out:    agg_share: the aggregated share
+ *             agg_pk: the aggregated x-only public key
+ *  In:        shares: all key generation shares for the partcipant's index
+ *    vss_commitments: coefficient commitments of all participants ordered by
+ *                     the x-only pubkeys of the participants
+ *           n_shares: the total number of shares
+ *          threshold: the minimum number of shares required to produce a
+ *                     signature
+ *               id33: the 33-byte ID of the participant whose shares are being
+ *                     aggregated
+ */
+SECP256K1_API int secp256k1_frost_share_agg(
+    const secp256k1_context *ctx,
+    secp256k1_frost_share *agg_share,
+    secp256k1_xonly_pubkey *agg_pk,
+    const secp256k1_frost_share * const *shares,
+    const secp256k1_pubkey * const *vss_commitments,
+    size_t n_shares,
+    size_t threshold,
+    const unsigned char *id33
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(8);
+
+/** Verifies a share received during a key generation session
+ *
+ *  The signature is verified against the VSS commitment received with the
+ *  share. This is only useful for purposes of determining which share(s) are
+ *  invalid if share_agg returns an error.
+ *
+ *  Returns: 0 if the arguments are invalid or the share does not verify, 1
+ *           otherwise
+ *  Args         ctx: pointer to a context object
+ *  In:    threshold: the minimum number of signers required to produce a
+ *                    signature
+ *              id33: the 33-byte participant ID of the share recipient
+ *             share: pointer to a key generation share
+ *    vss_commitment: the VSS commitment associated with the share
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_share_verify(
+    const secp256k1_context *ctx,
+    size_t threshold,
+    const unsigned char *id33,
+    const secp256k1_frost_share *share,
+    const secp256k1_pubkey * const *vss_commitment
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
+
+/** Computes a public verification share used for verifying partial signatures
+ *
+ *  Returns: 0 if the arguments are invalid, 1 otherwise
+ *  Args:        ctx: pointer to a context object
+ *  Out:    pubshare: pointer to a struct to store the public verification
+ *                    share
+ *  In:    threshold: the minimum number of signers required to produce a
+ *                    signature
+ *              id33: the 33-byte participant ID of the participant whose
+ *                    partial signature will be verified with the pubshare
+ *   vss_commitments: coefficient commitments of all participants
+ *    n_participants: the total number of participants
+ */
+SECP256K1_API int secp256k1_frost_compute_pubshare(
+    const secp256k1_context *ctx,
+    secp256k1_pubkey *pubshare,
+    size_t threshold,
+    const unsigned char *id33,
+    const secp256k1_pubkey * const *vss_commitments,
     size_t n_participants
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
 
 /** Obtain the aggregate public key from a FROST x-only aggregate public key.
  *
@@ -226,7 +315,7 @@ SECP256K1_API int secp256k1_frost_shares_trusted_gen(
  *  Args:        ctx: pointer to a context object
  *  Out:   ec_agg_pk: the FROST-aggregated public key.
  *  In: xonly_agg_pk: the aggregated x-only public key that is the output of
- *                    `secp256k1_frost_shares_gen`
+ *                    `secp256k1_frost_share_agg`
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_get(
     const secp256k1_context *ctx,
@@ -241,7 +330,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_get(
  *  Out: tweak_cache: pointer to a frost_tweak_cache struct that is required
  *                    for key tweaking
  *  In:       agg_pk: the aggregated x-only public key that is the output of
- *                    `secp256k1_frost_shares_gen`
+ *                    `secp256k1_frost_share_agg`
  */
 SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_tweak(
     const secp256k1_context *ctx,
@@ -257,7 +346,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_tweak(
  *  the following pseudocode buf and buf2 have identical contents (absent
  *  earlier failures).
  *
- *  secp256k1_frost_shares_gen(..., xonly_agg_pk, ...)
+ *  secp256k1_frost_share_agg(..., xonly_agg_pk, ...)
  *  secp256k1_frost_pubkey_tweak(..., tweak_cache, xonly_agg_pk)
  *  secp256k1_frost_pubkey_ec_tweak_add(..., output_pk, tweak_cache, tweak32)
  *  secp256k1_ec_pubkey_serialize(..., buf, output_pk)
@@ -300,7 +389,7 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_pubkey_ec_tweak_a
  *  the following pseudocode xonly_pubkey_tweak_add_check (absent earlier
  *  failures) returns 1.
  *
- *  secp256k1_frost_shares_gen(..., agg_pk, ...)
+ *  secp256k1_frost_share_agg(..., agg_pk, ...)
  *  secp256k1_frost_pubkey_tweak(..., tweak_cache, agg_pk)
  *  secp256k1_frost_pubkey_xonly_tweak_add(..., output_pk, tweak_cache, tweak32)
  *  secp256k1_xonly_pubkey_serialize(..., buf, output_pk)
@@ -387,10 +476,10 @@ SECP256K1_API int secp256k1_frost_nonce_gen(
 ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
 
 /** Takes the public nonces of all signers and computes a session that is
- * required for signing and verification of partial signatures. The participant
+ *  required for signing and verification of partial signatures. The participant
- * IDs can be sorted before combining, but the corresponding pubnonces must be
+ *  IDs can be sorted before combining, but the corresponding pubnonces must be
- * resorted as well. All signers must use the same sorting of pubnonces,
+ *  resorted as well. All signers must use the same sorting of pubnonces,
- * otherwise signing will fail.
+ *  otherwise signing will fail.
  *
  *  Returns: 0 if the arguments are invalid or if some signer sent invalid
  *           pubnonces, 1 otherwise
@@ -401,9 +490,9 @@ SECP256K1_API int secp256k1_frost_nonce_gen(
  *                      greater than 0.
  *               msg32: the 32-byte message to sign
  *              agg_pk: the FROST-aggregated public key
- *               my_id: the ID of the participant who will use the session for
+ *            myd_id33: the 33-byte ID of the participant who will use the
- *                      signing
+ *                      session for signing
-*                  ids: array of the IDs of the signers
+ *               ids33: array of the 33-byte participant IDs of the signers
  *         tweak_cache: pointer to frost_tweak_cache struct (can be NULL)
  *             adaptor: optional pointer to an adaptor point encoded as a
  *                      public key if this signing session is part of an
@@ -416,11 +505,11 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_frost_nonce_process(
     size_t n_pubnonces,
     const unsigned char *msg32,
     const secp256k1_xonly_pubkey *agg_pk,
-    size_t my_id,
+    const unsigned char *my_id33,
-    const size_t *ids,
+    const unsigned char * const* ids33,
     const secp256k1_frost_tweak_cache *tweak_cache,
     const secp256k1_pubkey *adaptor
-) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(6) SECP256K1_ARG_NONNULL(8);
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(6) SECP256K1_ARG_NONNULL(7) SECP256K1_ARG_NONNULL(8);
 
 /** Produces a partial signature
  *
@@ -458,7 +547,7 @@ SECP256K1_API int secp256k1_frost_partial_sign(
  *    1. The `tweak_cache` argument is identical to the one used to create the
  *       `session` with `frost_nonce_process`.
  *    2. The `pubshare` argument must be the output of
- *       `secp256k1_frost_shares_trusted_gen` for the signer's 'pk'.
+ *       `secp256k1_frost_compute_pubshare` for the signer's ID.
  *    3. The `pubnonce` argument must be identical to the one sent by the
  *       signer and used to create the `session` with `frost_nonce_process`.
  *
@@ -472,7 +561,7 @@ SECP256K1_API int secp256k1_frost_partial_sign(
  *          pubnonce: public nonce of the signer in the signing session
  *          pubshare: public verification share of the signer in the signing
  *                    session that is the output of
- *                    `secp256k1_frost_shares_trusted_gen`
+ *                    `secp256k1_frost_compute_pubshare`
  *           session: pointer to the session that was created with
  *                    `frost_nonce_process`
  *       tweak_cache: pointer to frost_tweak_cache struct (can be NULL)

src/ctime_tests.c

@@ -356,8 +356,10 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) {
 
 #ifdef ENABLE_MODULE_FROST
     {
-        secp256k1_xonly_pubkey pk;
+        secp256k1_pubkey pk[2];
+        secp256k1_xonly_pubkey agg_pk;
         unsigned char session_id[32];
+        unsigned char seed[2][32];
         secp256k1_frost_secnonce secnonce[2];
         secp256k1_frost_pubnonce pubnonce[2];
         const secp256k1_frost_pubnonce *pubnonce_ptr[2];
@@ -370,48 +372,86 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) {
         secp256k1_pubkey adaptor;
         unsigned char pre_sig[64];
         int nonce_parity;
-        secp256k1_frost_share shares[2];
+        secp256k1_frost_share shares[2][2];
-        secp256k1_pubkey pubshares[2];
+        const secp256k1_frost_share *share_ptr[2];
-        size_t ids[2];
+        secp256k1_frost_share agg_share;
+        const secp256k1_pubkey *vss_ptr[2];
+        unsigned char pok[2][64];
+        secp256k1_pubkey vss_commitment[2][2];
+        unsigned char key2[32];
+        secp256k1_keypair keypair2;
+        unsigned char id[2][33];
+        const unsigned char *id_ptr[2];
+        size_t size = 33;
 
+        id_ptr[0] = id[0];
+        id_ptr[1] = id[1];
         pubnonce_ptr[0] = &pubnonce[0];
         pubnonce_ptr[1] = &pubnonce[1];
         SECP256K1_CHECKMEM_DEFINE(key, 32);
+        memcpy(seed[0], key, 32);
+        seed[0][0] = seed[0][0] + 1;
+        memcpy(seed[0], key, 32);
+        seed[1][0] = seed[1][0] + 2;
         memcpy(extra_input, key, sizeof(extra_input));
-        extra_input[0] = extra_input[0] + 1;
+        extra_input[0] = extra_input[0] + 3;
         memcpy(sec_adaptor, key, sizeof(sec_adaptor));
-        sec_adaptor[0] = extra_input[0] + 2;
+        sec_adaptor[0] = extra_input[0] + 4;
+        memcpy(key2, key, sizeof(key2));
+        key2[0] = key2[0] + 5;
         memcpy(session_id, key, sizeof(session_id));
-        session_id[0] = session_id[0] + 3;
+        session_id[0] = session_id[0] + 6;
         partial_sig_ptr[0] = &partial_sig;
-        ids[0] = 1;
+        share_ptr[0] = &shares[0][0];
-        ids[1] = 2;
+        share_ptr[1] = &shares[1][0];
+        vss_ptr[0] = vss_commitment[0];
+        vss_ptr[1] = vss_commitment[1];
+
+        CHECK(secp256k1_keypair_create(ctx, &keypair, key));
+        CHECK(secp256k1_keypair_create(ctx, &keypair2, key2));
+        CHECK(secp256k1_keypair_pub(ctx, &pk[0], &keypair));
+        CHECK(secp256k1_keypair_pub(ctx, &pk[1], &keypair2));
+        CHECK(secp256k1_ec_pubkey_serialize(ctx, id[0], &size, &pk[0], SECP256K1_EC_COMPRESSED));
+        CHECK(secp256k1_ec_pubkey_serialize(ctx, id[1], &size, &pk[1], SECP256K1_EC_COMPRESSED));
 
         /* shares_gen */
         SECP256K1_CHECKMEM_UNDEFINE(key, 32);
-        ret = secp256k1_frost_shares_trusted_gen(ctx, shares, pubshares, &pk, key, 2, 2);
+        SECP256K1_CHECKMEM_UNDEFINE(key2, 32);
+        SECP256K1_CHECKMEM_UNDEFINE(seed[0], 32);
+        SECP256K1_CHECKMEM_UNDEFINE(seed[1], 32);
+        ret = secp256k1_frost_shares_gen(ctx, shares[0], vss_commitment[0], pok[0], seed[0], 2, 2, id_ptr);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        ret = secp256k1_frost_shares_gen(ctx, shares[1], vss_commitment[1], pok[1], seed[1], 2, 2, id_ptr);
+        SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
+        CHECK(ret == 1);
+        /* share_agg */
+        SECP256K1_CHECKMEM_DEFINE(&vss_commitment[0][0], sizeof(secp256k1_pubkey));
+        SECP256K1_CHECKMEM_DEFINE(&vss_commitment[0][1], sizeof(secp256k1_pubkey));
+        SECP256K1_CHECKMEM_DEFINE(&vss_commitment[1][0], sizeof(secp256k1_pubkey));
+        SECP256K1_CHECKMEM_DEFINE(&vss_commitment[1][1], sizeof(secp256k1_pubkey));
+        SECP256K1_CHECKMEM_DEFINE(pok[0], 64);
+        ret = secp256k1_frost_share_agg(ctx, &agg_share, &agg_pk, share_ptr, vss_ptr, 2, 2, id_ptr[0]);
         SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
         CHECK(ret == 1);
-        SECP256K1_CHECKMEM_UNDEFINE(&shares[0], sizeof(shares[0]));
-        SECP256K1_CHECKMEM_UNDEFINE(&shares[1], sizeof(shares[1]));
         /* nonce_gen */
         SECP256K1_CHECKMEM_UNDEFINE(session_id, sizeof(session_id));
         CHECK(secp256k1_ec_pubkey_create(ctx, &adaptor, sec_adaptor));
         SECP256K1_CHECKMEM_UNDEFINE(extra_input, sizeof(extra_input));
         SECP256K1_CHECKMEM_UNDEFINE(sec_adaptor, sizeof(sec_adaptor));
-        CHECK(secp256k1_frost_pubkey_tweak(ctx, &cache, &pk) == 1);
+        CHECK(secp256k1_frost_pubkey_tweak(ctx, &cache, &agg_pk) == 1);
-        ret = secp256k1_frost_nonce_gen(ctx, &secnonce[0], &pubnonce[0], session_id, &shares[0], msg, &pk, extra_input);
+        ret = secp256k1_frost_nonce_gen(ctx, &secnonce[0], &pubnonce[0], session_id, &agg_share, msg, &agg_pk, extra_input);
         SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
         CHECK(ret == 1);
-        ret = secp256k1_frost_nonce_gen(ctx, &secnonce[1], &pubnonce[1], session_id, &shares[1], msg, &pk, extra_input);
+        ret = secp256k1_frost_nonce_gen(ctx, &secnonce[1], &pubnonce[1], session_id, &agg_share, msg, &agg_pk, extra_input);
         SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
         CHECK(ret == 1);
         /* partial_sign */
-        CHECK(secp256k1_frost_nonce_process(ctx, &session, pubnonce_ptr, 2, msg, &pk, 1, ids, &cache, &adaptor) == 1);
+        CHECK(secp256k1_frost_nonce_process(ctx, &session, pubnonce_ptr, 2, msg, &agg_pk, id_ptr[0], id_ptr, &cache, &adaptor) == 1);
         ret = secp256k1_keypair_create(ctx, &keypair, key);
         SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
         CHECK(ret == 1);
-        ret = secp256k1_frost_partial_sign(ctx, &partial_sig, &secnonce[0], &shares[0], &session, &cache);
+        ret = secp256k1_frost_partial_sign(ctx, &partial_sig, &secnonce[0], &agg_share, &session, &cache);
         SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
         CHECK(ret == 1);
         /* adapt */
@@ -425,7 +465,7 @@ static void run_tests(secp256k1_context *ctx, unsigned char *key) {
         /* extract_adaptor */
         ret = secp256k1_frost_extract_adaptor(ctx, sec_adaptor, sig, pre_sig, nonce_parity);
         SECP256K1_CHECKMEM_DEFINE(&ret, sizeof(ret));
-        CHECK(ret == 1);
+        CHECK(ret == 1); 
     }
 #endif
 }

src/modules/frost/adaptor_impl.h

@@ -1,5 +1,5 @@
 /***********************************************************************
- * Copyright (c) 2022-2023 Jesse Posner                                *
+ * Copyright (c) 2022-2024 Jesse Posner                                *
  * Distributed under the MIT software license, see the accompanying    *
  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
  ***********************************************************************/

src/modules/frost/frost.md

@@ -9,33 +9,50 @@ The following sections contain additional notes on the API of the frost module
 
 Users of the frost module must take great care to make sure of the following:
 
-1. The dealer establishes a secure communications channel with each participant
+1. Each participant exchanges public keys for identification and authentication
-   and uses that channel to transmit shares during key generation.
+   purposes. Partipants must provide the same public key to each other
-2. A unique set of coefficients per key generation session is generated in
+   participant.
-   `secp256k1_frost_share_gen`. See the corresponding comment in
+2. Each participant establishes a secure communications channel with each other
+   participant and uses that channel to transmit shares and commitments during
+   key generation.
+3. A unique set of coefficients per key generation session is generated in
+   `secp256k1_frost_shares_gen`. See the corresponding comment in
    `include/secp256k1_frost.h` for how to ensure that.
-3. The `pubnonces` provided to `secp256k1_frost_nonce_process` are sorted by
+4. The `pubnonces` provided to `secp256k1_frost_nonce_process` are sorted by
    the corresponding lexicographic ordering of the x-only pubkey of each
-   participant, and the `pubkeys` provided to `secp256k1_frost_nonce_process`
+   participant, and the `ids33` provided to `secp256k1_frost_nonce_process`
    are sorted lexicographically.
-4. A unique nonce per signing session is generated in
+5. A unique nonce per signing session is generated in `secp256k1_frost_nonce_gen`.
-   `secp256k1_frost_nonce_gen`. See the corresponding comment in
+   See the corresponding comment in `include/secp256k1_frost.h` for how to ensure that.
-   `include/secp256k1_frost.h` for how to ensure that.
+6. The `secp256k1_frost_secnonce` structure is never copied or serialized.
-5. The `secp256k1_frost_secnonce` structure is never copied or serialized. See
+   See also the comment on `secp256k1_frost_secnonce` in `include/secp256k1_frost.h`.
-   also the comment on `secp256k1_frost_secnonce` in
+7. Opaque data structures are never written to or read from directly.
-   `include/secp256k1_frost.h`.
+   Instead, only the provided accessor functions are used.
-6. Opaque data structures are never written to or read from directly. Instead,
+8. If adaptor signatures are used, all partial signatures are verified.
-   only the provided accessor functions are used.
-7. If adaptor signatures are used, all partial signatures are verified.
 
 # Key Generation
 
-1. A trusted dealer generates shares with `secp256k1_frost_shares_trusted_gen`
+1. Generate a keypair with `secp256k1_keypair_create` and obtain the x-only
-   and distributes a share and the public key to each participant using a
+   public key with `secp256k1_keypair_xonly_pub`, and distribute it to each
-   secure channel.
+   other participant to be used as an authentication key and identifier.
+2. Generate a VSS commitment, proof-of-knowledge, and shares with
+   `secp256k1_frost_shares_gen`. The VSS commitment and proof-of-knowledge must
+   be broadcast to all participants. Assign each participant a share according
+   to the order of `ids33` and distribute the shares to the participants using
+   a secure channel.
+3. After receiving a share and commitment set from each participant, call
+   `secp256k1_frost_share_agg` to compute the aggregate share, group public
+   key, and VSS hash. If this function returns an error,
+   `secp256k1_frost_share_verify` is called on each share to determine which
+   participants submitted faulty shares.
+4. Optionally compute the public verification share by calling
+   `secp256k1_frost_compute_pubshare` with the x-only public key of each
+   participant. This share is required by `secp256k1_frost_partial_sig_verify`
+   to verify partial signatures generated by `secp256k1_frost_partial_sign`.
 
 # Tweaking
 
+
 A (Taproot) tweak can be added to the resulting public key with
 `secp256k1_xonly_pubkey_tweak_add`, after converting it to an xonly pubkey if
 necessary with `secp256k1_xonly_pubkey_from_pubkey`.

src/modules/frost/keygen.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2023 Jesse Posner                               *
+ * Copyright (c) 2021-2024 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/
@@ -23,4 +23,6 @@ static int secp256k1_tweak_cache_load(const secp256k1_context* ctx, secp256k1_tw
 
 static int secp256k1_frost_share_load(const secp256k1_context* ctx, secp256k1_scalar *s, const secp256k1_frost_share* share);
 
+static int secp256k1_frost_compute_indexhash(secp256k1_scalar *indexhash, const unsigned char *id33);
+
 #endif

src/modules/frost/keygen_impl.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2023 Jesse Posner                               *
+ * Copyright (c) 2021-2024 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/
@@ -53,6 +53,24 @@ static int secp256k1_tweak_cache_load(const secp256k1_context* ctx, secp256k1_tw
     return 1;
 }
 
+/* Computes indexhash = tagged_hash(pk) */
+static int secp256k1_frost_compute_indexhash(secp256k1_scalar *indexhash, const unsigned char *id33) {
+    secp256k1_sha256 sha;
+    unsigned char buf[32];
+
+    secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/index", sizeof("FROST/index") - 1);
+    secp256k1_sha256_write(&sha, id33, 33);
+    secp256k1_sha256_finalize(&sha, buf);
+    secp256k1_scalar_set_b32(indexhash, buf, NULL);
+    /* The x-coordinate must not be zero (see
+     * draft-irtf-cfrg-frost-08#section-4.2.2) */
+    if (secp256k1_scalar_is_zero(indexhash)) {
+        return 0;
+    }
+
+    return 1;
+}
+
 static const unsigned char secp256k1_frost_share_magic[4] = { 0xa1, 0x6a, 0x42, 0x03 };
 
 static void secp256k1_frost_share_save(secp256k1_frost_share* share, secp256k1_scalar *s) {
@@ -63,8 +81,6 @@ static void secp256k1_frost_share_save(secp256k1_frost_share* share, secp256k1_s
 static int secp256k1_frost_share_load(const secp256k1_context* ctx, secp256k1_scalar *s, const secp256k1_frost_share* share) {
     int overflow;
 
-    /* The magic is non-secret so it can be declassified to allow branching. */
-    secp256k1_declassify(ctx, &share->data[0], 4);
     ARG_CHECK(secp256k1_memcmp_var(&share->data[0], secp256k1_frost_share_magic, 4) == 0);
     secp256k1_scalar_set_b32(s, &share->data[4], &overflow);
     /* Parsed shares cannot overflow */
@@ -95,14 +111,82 @@ int secp256k1_frost_share_parse(const secp256k1_context* ctx, secp256k1_frost_sh
     return 1;
 }
 
-int secp256k1_frost_shares_trusted_gen(const secp256k1_context *ctx, secp256k1_frost_share *shares, secp256k1_pubkey *pubshares, secp256k1_xonly_pubkey *pk, const unsigned char *seed32, size_t threshold, size_t n_participants) {
+static void secp256k1_frost_derive_coeff(secp256k1_scalar *coeff, const unsigned char *polygen32, size_t i) {
     secp256k1_sha256 sha;
+    unsigned char buf[32];
+
+    secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/coeffgen", sizeof("FROST/coeffgen") - 1);
+    secp256k1_sha256_write(&sha, polygen32, 32);
+    secp256k1_write_be64(&buf[0], i);
+    secp256k1_sha256_write(&sha, buf, 8);
+    secp256k1_sha256_finalize(&sha, buf);
+    secp256k1_scalar_set_b32(coeff, buf, NULL);
+}
+
+static int secp256k1_frost_vss_gen(const secp256k1_context *ctx, secp256k1_pubkey *vss_commitment, unsigned char *pok64, const unsigned char *polygen32, size_t threshold) {
+    secp256k1_sha256 sha;
+    unsigned char buf[32];
+    secp256k1_keypair keypair;
     secp256k1_gej rj;
     secp256k1_ge rp;
-    unsigned char polygen[32];
+    size_t i;
-    size_t i, j;
+    int ret = 1;
+
+    for (i = 0; i < threshold; i++) {
+        secp256k1_scalar coeff_i;
+
+        secp256k1_frost_derive_coeff(&coeff_i, polygen32, i);
+        /* Compute proof-of-knowledge for constant term */
+        if (i == threshold - 1) {
+            secp256k1_scalar_get_b32(buf, &coeff_i);
+            ret &= secp256k1_keypair_create(ctx, &keypair, buf);
+
+            secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/KeygenPoK", sizeof("FROST/KeygenPoK") - 1);
+            secp256k1_sha256_finalize(&sha, buf);
+
+            ret &= secp256k1_schnorrsig_sign32(ctx, pok64, buf, &keypair, NULL);
+        }
+
+        /* Compute commitment to each coefficient */
+        secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &coeff_i);
+        secp256k1_ge_set_gej(&rp, &rj);
+        secp256k1_pubkey_save(&vss_commitment[threshold - i - 1], &rp);
+    }
+    return ret;
+}
+
+static int secp256k1_frost_share_gen(secp256k1_frost_share *share, const unsigned char *polygen32, size_t threshold, const unsigned char *id33) {
+    secp256k1_scalar idx;
+    secp256k1_scalar share_i;
+    size_t i;
+    int ret = 1;
+
+    /* Derive share */
+    /* See draft-irtf-cfrg-frost-08#appendix-C.1 */
+    secp256k1_scalar_set_int(&share_i, 0);
+    if (!secp256k1_frost_compute_indexhash(&idx, id33)) {
+        return 0;
+    }
+    for (i = 0; i < threshold; i++) {
+        secp256k1_scalar coeff_i;
+
+        secp256k1_frost_derive_coeff(&coeff_i, polygen32, i);
+        /* Horner's method to evaluate polynomial to derive shares */
+        secp256k1_scalar_add(&share_i, &share_i, &coeff_i);
+        if (i < threshold - 1) {
+            secp256k1_scalar_mul(&share_i, &share_i, &idx);
+        }
+    }
+    secp256k1_frost_share_save(share, &share_i);
+
+    return ret;
+}
+
+int secp256k1_frost_shares_gen(const secp256k1_context *ctx, secp256k1_frost_share *shares, secp256k1_pubkey *vss_commitment, unsigned char *pok64, const unsigned char *seed32, size_t threshold, size_t n_participants, const unsigned char * const* ids33) {
+    secp256k1_sha256 sha;
+    unsigned char polygen[32];
+    size_t i;
     int ret = 1;
-    int pk_parity = 0;
 
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
@@ -110,72 +194,257 @@ int secp256k1_frost_shares_trusted_gen(const secp256k1_context *ctx, secp256k1_f
     for (i = 0; i < n_participants; i++) {
         memset(&shares[i], 0, sizeof(shares[i]));
     }
-    ARG_CHECK(pubshares != NULL);
+    ARG_CHECK(vss_commitment != NULL);
-    ARG_CHECK(pk != NULL);
+    ARG_CHECK(pok64 != NULL);
     ARG_CHECK(seed32 != NULL);
+    ARG_CHECK(ids33 != NULL);
     ARG_CHECK(threshold > 1);
     ARG_CHECK(n_participants >= threshold);
 
-    /* Commit to threshold, n_participants, and seed */
+    /* Commit to all inputs */
-    secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/trusted-shares-polygen", sizeof("FROST/trusted-shares-polygen") - 1);
+    secp256k1_sha256_initialize(&sha);
     secp256k1_sha256_write(&sha, seed32, 32);
     secp256k1_write_be64(&polygen[0], threshold);
     secp256k1_write_be64(&polygen[8], n_participants);
     secp256k1_sha256_write(&sha, polygen, 16);
+    for (i = 0; i < n_participants; i++) {
+        secp256k1_sha256_write(&sha, ids33[i], 33);
+    }
     secp256k1_sha256_finalize(&sha, polygen);
 
-    /* Derive shares */
+    ret &= secp256k1_frost_vss_gen(ctx, vss_commitment, pok64, polygen, threshold);
-    /* See draft-irtf-cfrg-frost-08#appendix-C.1 */
+
     for (i = 0; i < n_participants; i++) {
-        secp256k1_scalar share_i, idx;
+        ret &= secp256k1_frost_share_gen(&shares[i], polygen, threshold, ids33[i]);
-
-        secp256k1_scalar_set_int(&share_i, 0);
-
-        for (j = 0; j < threshold; j++) {
-            unsigned char buf[32];
-            secp256k1_scalar coeff_i;
-
-            secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/trusted-shares-coeffgen", sizeof("FROST/trusted-shares-coeffgen") - 1);
-            secp256k1_sha256_write(&sha, polygen, 32);
-            secp256k1_write_be64(&buf[0], j);
-            secp256k1_sha256_write(&sha, buf, 8);
-            secp256k1_sha256_finalize(&sha, buf);
-            secp256k1_scalar_set_b32(&coeff_i, buf, NULL);
-
-            /* Horner's method to evaluate polynomial to derive shares */
-            secp256k1_scalar_add(&share_i, &share_i, &coeff_i);
-            if (j < threshold - 1) {
-                secp256k1_scalar_set_int(&idx, i + 1);
-                secp256k1_scalar_mul(&share_i, &share_i, &idx);
-            }
-
-            /* Compute x-only public key for constant term */
-            if (i == 0 && j == threshold - 1) {
-                /* Compute commitment to constant term */
-                secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &coeff_i);
-                secp256k1_ge_set_gej(&rp, &rj);
-                /* The commitment is non-secret so it can be declassified to
-                 * allow branching. */
-                secp256k1_declassify(ctx, &rp, sizeof(rp));
-                secp256k1_fe_normalize_var(&rp.y);
-                pk_parity = secp256k1_extrakeys_ge_even_y(&rp);
-                secp256k1_xonly_pubkey_save(pk, &rp);
-            }
-        }
-
-        if (pk_parity == 1) {
-            secp256k1_scalar_negate(&share_i, &share_i);
-        }
-        secp256k1_frost_share_save(&shares[i], &share_i);
-        /* Compute pubshare */
-        secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &rj, &share_i);
-        secp256k1_ge_set_gej(&rp, &rj);
-        secp256k1_pubkey_save(&pubshares[i], &rp);
     }
 
     return ret;
 }
 
+typedef struct {
+    const secp256k1_context *ctx;
+    secp256k1_scalar idx;
+    secp256k1_scalar idxn;
+    const secp256k1_pubkey * const* vss_commitment;
+} secp256k1_frost_verify_share_ecmult_data;
+
+typedef struct {
+    const secp256k1_context *ctx;
+    secp256k1_scalar idx;
+    secp256k1_scalar idxn;
+    const secp256k1_pubkey * const* vss_commitments;
+    size_t threshold;
+} secp256k1_frost_compute_pubshare_ecmult_data;
+
+typedef struct {
+    const secp256k1_context *ctx;
+    const secp256k1_pubkey * const* pks;
+    size_t threshold;
+} secp256k1_frost_pubkey_combine_ecmult_data;
+
+static int secp256k1_frost_verify_share_ecmult_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data) {
+    secp256k1_frost_verify_share_ecmult_data *ctx = (secp256k1_frost_verify_share_ecmult_data *) data;
+    if (!secp256k1_pubkey_load(ctx->ctx, pt, *(ctx->vss_commitment)+idx)) {
+        return 0;
+    }
+    *sc = ctx->idxn;
+    secp256k1_scalar_mul(&ctx->idxn, &ctx->idxn, &ctx->idx);
+
+    return 1;
+}
+
+static int secp256k1_frost_compute_pubshare_ecmult_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data) {
+    secp256k1_frost_compute_pubshare_ecmult_data *ctx = (secp256k1_frost_compute_pubshare_ecmult_data *) data;
+
+    if (!secp256k1_pubkey_load(ctx->ctx, pt, &ctx->vss_commitments[idx/ctx->threshold][idx % ctx->threshold])) {
+        return 0;
+    }
+    if (idx != 0 && idx % ctx->threshold == 0) {
+        secp256k1_scalar_set_int(&ctx->idxn, 1);
+    }
+    *sc = ctx->idxn;
+    secp256k1_scalar_mul(&ctx->idxn, &ctx->idxn, &ctx->idx);
+
+    return 1;
+}
+
+static int secp256k1_frost_pubkey_combine_callback(secp256k1_scalar *sc, secp256k1_ge *pt, size_t idx, void *data) {
+    secp256k1_frost_pubkey_combine_ecmult_data *ctx = (secp256k1_frost_pubkey_combine_ecmult_data *) data;
+
+    secp256k1_scalar_set_int(sc, 1);
+    /* the public key is the first index of each set of coefficients */
+    return secp256k1_pubkey_load(ctx->ctx, pt, &ctx->pks[idx][0]);
+}
+
+/* See draft-irtf-cfrg-frost-08#appendix-C.2 */
+static int secp256k1_frost_vss_verify_internal(const secp256k1_context* ctx, size_t threshold, const unsigned char *id33, const secp256k1_scalar *share, const secp256k1_pubkey * const* vss_commitment) {
+    secp256k1_scalar share_neg;
+    secp256k1_gej tmpj, snj;
+    secp256k1_ge sng;
+    secp256k1_frost_verify_share_ecmult_data verify_share_ecmult_data;
+
+    ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
+
+    /* Use an EC multi-multiplication to verify the following equation:
+     *   0 = - share_i*G + idx^0*vss_commitment[0]
+     *                   + ...
+     *                   + idx^(threshold - 1)*vss_commitment[threshold - 1]*/
+    verify_share_ecmult_data.ctx = ctx;
+    verify_share_ecmult_data.vss_commitment = vss_commitment;
+    /* Evaluate the public polynomial at the idx */
+    if (!secp256k1_frost_compute_indexhash(&verify_share_ecmult_data.idx, id33)) {
+        return 0;
+    }
+    secp256k1_scalar_set_int(&verify_share_ecmult_data.idxn, 1);
+    /* TODO: add scratch */
+    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &tmpj, NULL, secp256k1_frost_verify_share_ecmult_callback, (void *) &verify_share_ecmult_data, threshold)) {
+        return 0;
+    }
+    secp256k1_scalar_negate(&share_neg, share);
+    secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &snj, &share_neg);
+    secp256k1_ge_set_gej(&sng, &snj);
+    secp256k1_gej_add_ge(&tmpj, &tmpj, &sng);
+    return secp256k1_gej_is_infinity(&tmpj);
+}
+
+/* See draft-irtf-cfrg-frost-08#appendix-C.2 */
+int secp256k1_frost_share_verify(const secp256k1_context* ctx, size_t threshold, const unsigned char *id33, const secp256k1_frost_share *share, const secp256k1_pubkey * const* vss_commitment) {
+    secp256k1_scalar share_i;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(id33 != NULL);
+    ARG_CHECK(share != NULL);
+    ARG_CHECK(vss_commitment != NULL);
+    ARG_CHECK(threshold > 1);
+
+    if (!secp256k1_frost_share_load(ctx, &share_i, share)) {
+        return 0;
+    }
+
+    return secp256k1_frost_vss_verify_internal(ctx, threshold, id33, &share_i, vss_commitment);
+}
+
+int secp256k1_frost_compute_pubshare(const secp256k1_context* ctx, secp256k1_pubkey *pubshare, size_t threshold, const unsigned char *id33, const secp256k1_pubkey * const* vss_commitments, size_t n_participants) {
+    secp256k1_gej pkj;
+    secp256k1_ge pkp, tmp;
+    secp256k1_frost_compute_pubshare_ecmult_data compute_pubshare_ecmult_data;
+    secp256k1_frost_pubkey_combine_ecmult_data pubkey_combine_ecmult_data;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(pubshare != NULL);
+    memset(pubshare, 0, sizeof(*pubshare));
+    ARG_CHECK(id33 != NULL);
+    ARG_CHECK(vss_commitments != NULL);
+    ARG_CHECK(n_participants > 1);
+    ARG_CHECK(threshold > 1);
+
+    if (threshold > n_participants) {
+        return 0;
+    }
+
+    /* Use an EC multi-multiplication to compute the following equation:
+     *   agg_share_i*G = (
+     *      idx^0*vss_commitment[0][0] + ...
+     *                                 + idx^(t - 1)*vss_commitment[0][t - 1]
+     *   )                             + ...
+     *                                 + (
+     *      idx^0*vss_commitment[n - 1][0] + ...
+     *                                     + idx^(t - 1)*vss_commitment[n - 1][t - 1]
+     *   )*/
+    compute_pubshare_ecmult_data.ctx = ctx;
+    compute_pubshare_ecmult_data.vss_commitments = vss_commitments;
+    compute_pubshare_ecmult_data.threshold = threshold;
+    /* Evaluate the public polynomial at the idx */
+    if (!secp256k1_frost_compute_indexhash(&compute_pubshare_ecmult_data.idx, id33)) {
+        return 0;
+    }
+    secp256k1_scalar_set_int(&compute_pubshare_ecmult_data.idxn, 1);
+    /* TODO: add scratch */
+    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &pkj, NULL, secp256k1_frost_compute_pubshare_ecmult_callback, (void *) &compute_pubshare_ecmult_data, n_participants*threshold)) {
+        return 0;
+    }
+    secp256k1_ge_set_gej(&tmp, &pkj);
+
+    /* Combine pubkeys */
+    pubkey_combine_ecmult_data.ctx = ctx;
+    pubkey_combine_ecmult_data.pks = vss_commitments;
+    pubkey_combine_ecmult_data.threshold = threshold;
+
+    /* TODO: add scratch */
+    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &pkj, NULL, secp256k1_frost_pubkey_combine_callback, (void *) &pubkey_combine_ecmult_data, n_participants)) {
+        return 0;
+    }
+    secp256k1_ge_set_gej(&pkp, &pkj);
+    secp256k1_fe_normalize_var(&pkp.y);
+    if (secp256k1_fe_is_odd(&pkp.y)) {
+        secp256k1_ge_neg(&tmp, &tmp);
+    }
+
+    secp256k1_pubkey_save(pubshare, &tmp);
+
+    return 1;
+}
+
+int secp256k1_frost_share_agg(const secp256k1_context* ctx, secp256k1_frost_share *agg_share, secp256k1_xonly_pubkey *agg_pk, const secp256k1_frost_share * const* shares, const secp256k1_pubkey * const* vss_commitments, size_t n_shares, size_t threshold, const unsigned char *id33) {
+    secp256k1_frost_pubkey_combine_ecmult_data pubkey_combine_ecmult_data;
+    secp256k1_gej pkj;
+    secp256k1_ge pkp;
+    int pk_parity;
+    secp256k1_scalar acc;
+    size_t i;
+    int ret = 1;
+
+    VERIFY_CHECK(ctx != NULL);
+    ARG_CHECK(agg_share != NULL);
+    memset(agg_share, 0, sizeof(*agg_share));
+    ARG_CHECK(agg_pk != NULL);
+    memset(agg_pk, 0, sizeof(*agg_pk));
+    ARG_CHECK(shares != NULL);
+    ARG_CHECK(vss_commitments != NULL);
+    ARG_CHECK(id33 != NULL);
+    ARG_CHECK(n_shares > 1);
+    ARG_CHECK(threshold > 1);
+
+    if (threshold > n_shares) {
+        return 0;
+    }
+
+    secp256k1_scalar_clear(&acc);
+    for (i = 0; i < n_shares; i++) {
+        secp256k1_scalar share_i;
+
+        if (!secp256k1_frost_share_load(ctx, &share_i, shares[i])) {
+            return 0;
+        }
+        /* Verify share against commitments */
+        ret &= secp256k1_frost_vss_verify_internal(ctx, threshold, id33, &share_i, &vss_commitments[i]);
+        secp256k1_scalar_add(&acc, &acc, &share_i);
+    }
+
+    /* Combine pubkeys */
+    pubkey_combine_ecmult_data.ctx = ctx;
+    pubkey_combine_ecmult_data.pks = vss_commitments;
+    pubkey_combine_ecmult_data.threshold = threshold;
+
+    /* TODO: add scratch */
+    if (!secp256k1_ecmult_multi_var(&ctx->error_callback, NULL, &pkj, NULL, secp256k1_frost_pubkey_combine_callback, (void *) &pubkey_combine_ecmult_data, n_shares)) {
+        return 0;
+    }
+
+    secp256k1_ge_set_gej(&pkp, &pkj);
+    secp256k1_fe_normalize_var(&pkp.y);
+    pk_parity = secp256k1_extrakeys_ge_even_y(&pkp);
+    secp256k1_xonly_pubkey_save(agg_pk, &pkp);
+
+    /* Invert the aggregate share if the combined pubkey has an odd Y coordinate. */
+    if (pk_parity == 1) {
+        secp256k1_scalar_negate(&acc, &acc);
+    }
+    secp256k1_frost_share_save(agg_share, &acc);
+
+    return ret;
+}
+
 int secp256k1_frost_pubkey_get(const secp256k1_context* ctx, secp256k1_pubkey *ec_pk, const secp256k1_xonly_pubkey *xonly_pk) {
     secp256k1_ge pk;
 

src/modules/frost/main_impl.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2023 Jesse Posner                               *
+ * Copyright (c) 2021-2024 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/

src/modules/frost/session.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2023 Jesse Posner                               *
+ * Copyright (c) 2021-2024 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/

src/modules/frost/session_impl.h

@@ -1,5 +1,5 @@
 /**********************************************************************
- * Copyright (c) 2021-2023 Jesse Posner                               *
+ * Copyright (c) 2021-2024 Jesse Posner                               *
  * Distributed under the MIT software license, see the accompanying   *
  * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
  **********************************************************************/
@@ -313,7 +313,7 @@ int secp256k1_frost_nonce_gen(const secp256k1_context* ctx, secp256k1_frost_secn
     return ret;
 }
 
-static int secp256k1_frost_sum_nonces(const secp256k1_context* ctx, secp256k1_gej *summed_nonces, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces) {
+static int secp256k1_frost_sum_nonces(const secp256k1_context* ctx, secp256k1_gej *summed_nonces, const secp256k1_frost_pubnonce * const *pubnonces, size_t n_pubnonces) {
     size_t i;
     int j;
 
@@ -334,16 +334,19 @@ static int secp256k1_frost_sum_nonces(const secp256k1_context* ctx, secp256k1_ge
 
 /* TODO: consider updating to frost-08 to address maleability at the cost of performance */
 /* See https://github.com/cfrg/draft-irtf-cfrg-frost/pull/217 */
-static int secp256k1_frost_compute_noncehash(const secp256k1_context* ctx, unsigned char *noncehash, const unsigned char *msg, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *pk32, const size_t *ids) {
+static int secp256k1_frost_compute_noncehash(const secp256k1_context* ctx, unsigned char *noncehash, const unsigned char *msg, const secp256k1_frost_pubnonce * const *pubnonces, size_t n_pubnonces, const unsigned char *pk32, const unsigned char * const *ids33) {
     unsigned char buf[66];
     secp256k1_sha256 sha;
     size_t i;
 
     secp256k1_sha256_initialize_tagged(&sha, (unsigned char*)"FROST/noncecoef", sizeof("FROST/noncecoef") - 1);
+    /* TODO: sort by index */
     for (i = 0; i < n_pubnonces; i++) {
         secp256k1_scalar idx;
 
-        secp256k1_scalar_set_int(&idx, ids[i]);
+        if (!secp256k1_frost_compute_indexhash(&idx, ids33[i])) {
+            return 0;
+        }
         secp256k1_scalar_get_b32(buf, &idx);
         secp256k1_sha256_write(&sha, buf, 32);
         if (!secp256k1_frost_pubnonce_serialize(ctx, buf, pubnonces[i])) {
@@ -357,7 +360,7 @@ static int secp256k1_frost_compute_noncehash(const secp256k1_context* ctx, unsig
     return 1;
 }
 
-static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx, int *fin_nonce_parity, unsigned char *fin_nonce, secp256k1_scalar *b, secp256k1_gej *aggnoncej, const unsigned char *msg, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *pk32, const size_t *ids) {
+static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx, int *fin_nonce_parity, unsigned char *fin_nonce, secp256k1_scalar *b, secp256k1_gej *aggnoncej, const unsigned char *msg, const secp256k1_frost_pubnonce * const *pubnonces, size_t n_pubnonces, const unsigned char *pk32, const unsigned char * const *ids33) {
     unsigned char noncehash[32];
     secp256k1_ge fin_nonce_pt;
     secp256k1_gej fin_nonce_ptj;
@@ -365,7 +368,7 @@ static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx,
 
     secp256k1_ge_set_gej(&aggnonce[0], &aggnoncej[0]);
     secp256k1_ge_set_gej(&aggnonce[1], &aggnoncej[1]);
-    if (!secp256k1_frost_compute_noncehash(ctx, noncehash, msg, pubnonces, n_pubnonces, pk32, ids)) {
+    if (!secp256k1_frost_compute_noncehash(ctx, noncehash, msg, pubnonces, n_pubnonces, pk32, ids33)) {
         return 0;
     }
     /* fin_nonce = aggnonce[0] + b*aggnonce[1] */
@@ -386,7 +389,7 @@ static int secp256k1_frost_nonce_process_internal(const secp256k1_context* ctx,
     return 1;
 }
 
-static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const size_t *ids, size_t n_participants, size_t my_id) {
+static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const unsigned char * const *ids33, size_t n_participants, const unsigned char *my_id33) {
     size_t i;
     secp256k1_scalar num;
     secp256k1_scalar den;
@@ -394,11 +397,15 @@ static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const size_
 
     secp256k1_scalar_set_int(&num, 1);
     secp256k1_scalar_set_int(&den, 1);
-    secp256k1_scalar_set_int(&party_idx, my_id);
+    if (!secp256k1_frost_compute_indexhash(&party_idx, my_id33)) {
+        return 0;
+    }
     for (i = 0; i < n_participants; i++) {
         secp256k1_scalar mul;
 
-        secp256k1_scalar_set_int(&mul, ids[i]);
+        if (!secp256k1_frost_compute_indexhash(&mul, ids33[i])) {
+            return 0;
+        }
         if (secp256k1_scalar_eq(&mul, &party_idx)) {
             continue;
         }
@@ -415,7 +422,7 @@ static int secp256k1_frost_lagrange_coefficient(secp256k1_scalar *r, const size_
     return 1;
 }
 
-int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_session *session, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *msg32, const secp256k1_xonly_pubkey *pk, size_t my_id, const size_t *ids, const secp256k1_frost_tweak_cache *tweak_cache, const secp256k1_pubkey *adaptor) {
+int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_session *session, const secp256k1_frost_pubnonce * const* pubnonces, size_t n_pubnonces, const unsigned char *msg32, const secp256k1_xonly_pubkey *pk, const unsigned char *my_id33, const unsigned char * const *ids33, const secp256k1_frost_tweak_cache *tweak_cache, const secp256k1_pubkey *adaptor) {
     secp256k1_ge aggnonce_pt[2];
     secp256k1_gej aggnonce_ptj[2];
     unsigned char fin_nonce[32];
@@ -428,12 +435,10 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
     ARG_CHECK(session != NULL);
     ARG_CHECK(msg32 != NULL);
     ARG_CHECK(pubnonces != NULL);
-    ARG_CHECK(ids != NULL);
+    ARG_CHECK(ids33 != NULL);
+    ARG_CHECK(my_id33 != NULL);
+    ARG_CHECK(pk != NULL);
     ARG_CHECK(n_pubnonces > 1);
-    ARG_CHECK(my_id != 0);
-    for (i = 0; i < n_pubnonces; i++) {
-        ARG_CHECK(ids[i] != 0);
-    }
 
     if (!secp256k1_xonly_pubkey_serialize(ctx, pk32, pk)) {
         return 0;
@@ -448,7 +453,6 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
                here, we will never be able to determine who it is. Therefore, we
                should continue such that the culprit is revealed when collecting
                and verifying partial signatures.
-
                However, dealing with the point at infinity (loading,
                de-/serializing) would require a lot of extra code complexity.
                Instead, we set the aggregate nonce to some arbitrary point (the
@@ -472,7 +476,7 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
         }
         secp256k1_gej_add_ge_var(&aggnonce_ptj[0], &aggnonce_ptj[0], &adaptorp, NULL);
     }
-    if (!secp256k1_frost_nonce_process_internal(ctx, &session_i.fin_nonce_parity, fin_nonce, &session_i.noncecoef, aggnonce_ptj, msg32, pubnonces, n_pubnonces, pk32, ids)) {
+    if (!secp256k1_frost_nonce_process_internal(ctx, &session_i.fin_nonce_parity, fin_nonce, &session_i.noncecoef, aggnonce_ptj, msg32, pubnonces, n_pubnonces, pk32, ids33)) {
         return 0;
     }
 
@@ -496,7 +500,7 @@ int secp256k1_frost_nonce_process(const secp256k1_context* ctx, secp256k1_frost_
     }
     /* Update the challenge by multiplying the Lagrange coefficient to prepare
      * for signing. */
-    if (!secp256k1_frost_lagrange_coefficient(&l, ids, n_pubnonces, my_id)) {
+    if (!secp256k1_frost_lagrange_coefficient(&l, ids33, n_pubnonces, my_id33)) {
         return 0;
     }
     secp256k1_scalar_mul(&session_i.challenge, &session_i.challenge, &l);

src/modules/frost/tests_impl.h

@@ -1,5 +1,5 @@
 /***********************************************************************
- * Copyright (c) 2022, 2023 Jesse Posner                               *
+ * Copyright (c) 2022-2024 Jesse Posner                                *
  * Distributed under the MIT software license, see the accompanying    *
  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
  ***********************************************************************/
@@ -23,49 +23,77 @@
 #include "../../hash.h"
 #include "../../util.h"
 
+static int frost_create_pk(unsigned char *id, const unsigned char *sk) {
+    int ret;
+    secp256k1_pubkey pubkey_tmp;
+    size_t size = 33;
+
+    ret = secp256k1_ec_pubkey_create(CTX, &pubkey_tmp, sk);
+    ret &= secp256k1_ec_pubkey_serialize(CTX, id, &size, &pubkey_tmp, SECP256K1_EC_COMPRESSED);
+
+    return ret;
+}
+
 /* Simple (non-adaptor, non-tweaked) 3-of-5 FROST aggregate, sign, verify
  * test. */
 void frost_simple_test(void) {
+    unsigned char sk[5][32];
     secp256k1_frost_pubnonce pubnonce[5];
     const secp256k1_frost_pubnonce *pubnonce_ptr[5];
     unsigned char msg[32];
-    secp256k1_xonly_pubkey pk;
+    secp256k1_pubkey vss_commitment[5][3];
-    unsigned char seed[32];
+    const secp256k1_pubkey *vss_ptr[5];
-    secp256k1_frost_share shares[5];
+    unsigned char pok[5][64];
+    secp256k1_xonly_pubkey agg_pk;
+    unsigned char buf[5][32];
+    secp256k1_frost_share shares[5][5];
+    const secp256k1_frost_share *share_ptr[5];
+    secp256k1_frost_share agg_share[5];
     secp256k1_frost_secnonce secnonce[5];
-    secp256k1_pubkey pubshares[5];
+    secp256k1_pubkey pubshare[5];
     secp256k1_frost_partial_sig partial_sig[5];
     const secp256k1_frost_partial_sig *partial_sig_ptr[5];
     unsigned char final_sig[64];
     secp256k1_frost_session session;
-    int i;
+    int i, j;
-    size_t ids[5];
+    unsigned char id[5][33];
-
+    const unsigned char *id_ptr[5];
-    secp256k1_testrand256(seed);
 
     for (i = 0; i < 5; i++) {
+        secp256k1_testrand256(buf[i]);
+        secp256k1_testrand256(sk[i]);
+        vss_ptr[i] = vss_commitment[i];
         pubnonce_ptr[i] = &pubnonce[i];
         partial_sig_ptr[i] = &partial_sig[i];
-        ids[i] = i + 1;
+        id_ptr[i] = id[i];
-    }
 
-    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 5) == 1);
+        CHECK(frost_create_pk(id[i], sk[i]));
+    }
+    for (i = 0; i < 5; i++) {
+        CHECK(secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], buf[i], 3, 5, id_ptr) == 1);
+    }
+    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
+            share_ptr[j] = &shares[j][i];
+            CHECK(secp256k1_frost_share_verify(CTX, 3, id_ptr[i], share_ptr[j], &vss_ptr[j]) == 1);
+            CHECK(secp256k1_frost_compute_pubshare(CTX, &pubshare[j], 3, id_ptr[j], vss_ptr, 5) == 1);
+        }
+        CHECK(secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, vss_ptr, 5, 3, id_ptr[i]) == 1);
+    }
 
     secp256k1_testrand256(msg);
     for (i = 0; i < 3; i++) {
-        unsigned char session_id[32];
+        secp256k1_testrand256(buf[i]);
 
-        secp256k1_testrand256(session_id);
+        CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[i], &pubnonce[i], buf[i], &agg_share[i], NULL, NULL, NULL) == 1);
-
-        CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[i], &pubnonce[i], session_id, &shares[i], NULL, NULL, NULL) == 1);
     }
     for (i = 0; i < 3; i++) {
-        CHECK(secp256k1_frost_nonce_process(CTX, &session, pubnonce_ptr, 3, msg, &pk, ids[i], ids, NULL, NULL) == 1);
+        CHECK(secp256k1_frost_nonce_process(CTX, &session, pubnonce_ptr, 3, msg, &agg_pk, id_ptr[i], id_ptr, NULL, NULL) == 1);
-        CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[i], &secnonce[i], &shares[i], &session, NULL) == 1);
+        CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[i], &secnonce[i], &agg_share[i], &session, NULL) == 1);
-        CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[i], &pubnonce[i], &pubshares[i], &session, NULL) == 1);
+        CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[i], &pubnonce[i], &pubshare[i], &session, NULL) == 1);
     }
     CHECK(secp256k1_frost_partial_sig_agg(CTX, final_sig, &session, partial_sig_ptr, 3) == 1);
-    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &pk) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &agg_pk) == 1);
 }
 
 void frost_pubnonce_summing_to_inf(secp256k1_frost_pubnonce *pubnonce) {
@@ -107,11 +135,11 @@ void frost_api_tests(void) {
     unsigned char final_sig[64];
     unsigned char pre_sig[64];
     unsigned char buf[32];
-    /* unsigned char sk[5][32]; */
+    unsigned char sk[5][32];
     unsigned char max64[64];
     unsigned char zeros68[68] = { 0 };
     unsigned char session_id[5][32];
-    unsigned char seed[32];
+    unsigned char seed[5][32];
     secp256k1_frost_secnonce secnonce[5];
     secp256k1_frost_secnonce secnonce_tmp;
     secp256k1_frost_secnonce invalid_secnonce;
@@ -122,8 +150,8 @@ void frost_api_tests(void) {
     secp256k1_frost_pubnonce invalid_pubnonce;
     const secp256k1_frost_pubnonce *invalid_pubnonce_ptr[5];
     unsigned char msg[32];
-    secp256k1_xonly_pubkey pk;
+    secp256k1_xonly_pubkey agg_pk;
-    secp256k1_pubkey full_pk;
+    secp256k1_pubkey full_agg_pk;
     secp256k1_frost_tweak_cache tweak_cache;
     secp256k1_frost_tweak_cache invalid_tweak_cache;
     secp256k1_frost_session session[5];
@@ -134,13 +162,21 @@ void frost_api_tests(void) {
     unsigned char sec_adaptor[32];
     unsigned char sec_adaptor1[32];
     secp256k1_pubkey adaptor;
+    secp256k1_pubkey vss_commitment[5][3];
+    secp256k1_pubkey invalid_vss_commitment[5][3];
+    const secp256k1_pubkey *vss_ptr[5];
+    const secp256k1_pubkey *invalid_vss_ptr[5];
     secp256k1_pubkey invalid_vss_pk;
+    secp256k1_frost_share shares[5][5];
     secp256k1_frost_share invalid_share;
-    secp256k1_frost_share shares[5];
+    secp256k1_frost_share agg_share[5];
-    secp256k1_pubkey pubshares[5];
+    unsigned char pok[5][64];
-    int i;
+    const secp256k1_frost_share *share_ptr[5];
-    size_t ids[5];
+    const secp256k1_frost_share *invalid_share_ptr[5];
-    size_t invalid_ids[5];
+    secp256k1_pubkey pubshare[5];
+    int i, j;
+    unsigned char id[5][33];
+    const unsigned char *id_ptr[5];
 
     /** setup **/
     memset(max64, 0xff, sizeof(max64));
@@ -160,68 +196,158 @@ void frost_api_tests(void) {
     secp256k1_testrand256(sec_adaptor);
     secp256k1_testrand256(msg);
     secp256k1_testrand256(tweak);
-    secp256k1_testrand256(seed);
     CHECK(secp256k1_ec_pubkey_create(CTX, &adaptor, sec_adaptor) == 1);
     for (i = 0; i < 5; i++) {
         pubnonce_ptr[i] = &pubnonce[i];
+        vss_ptr[i] = vss_commitment[i];
+        invalid_vss_ptr[i] = invalid_vss_commitment[i];
         partial_sig_ptr[i] = &partial_sig[i];
         invalid_partial_sig_ptr[i] = &partial_sig[i];
-        ids[i] = i + 1;
+        id_ptr[i] = id[i];
-        invalid_ids[i] = i + 1;
         secp256k1_testrand256(session_id[i]);
+        secp256k1_testrand256(seed[i]);
+        secp256k1_testrand256(sk[i]);
+        CHECK(frost_create_pk(id[i], sk[i]));
     }
     invalid_pubnonce_ptr[0] = &invalid_pubnonce;
+    invalid_share_ptr[0] = &invalid_share;
     invalid_partial_sig_ptr[0] = &invalid_partial_sig;
-    invalid_ids[2] = 0;
+    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 3; j++) {
+            invalid_vss_commitment[i][j] = invalid_vss_pk;
+        }
+    }
 
     /** main test body **/
 
     /** Key generation **/
-    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 5) == 1);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, NULL, pubshares, &pk, seed, 3, 5));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, NULL, &pk, seed, 3, 5));
     for (i = 0; i < 5; i++) {
-        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+        CHECK(secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 3, 5, id_ptr) == 1);
-    }
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, NULL, vss_commitment[i], pok[i], seed[i], 3, 5, id_ptr));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, NULL, seed, 3, 5));
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, shares[i], NULL, pok[i], seed[i], 3, 5, id_ptr));
-    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
-        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+            CHECK(frost_memcmp_and_randomize(shares[i][j].data, zeros68, sizeof(shares[i][j].data)) == 0);
-    }
+        }
-    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, NULL, 3, 5));
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], NULL, seed[i], 3, 5, id_ptr));
-    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
-        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+            CHECK(frost_memcmp_and_randomize(shares[i][j].data, zeros68, sizeof(shares[i][j].data)) == 0);
-    }
+        }
-    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 0, 5));
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], NULL, 3, 5, id_ptr));
-    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
-        CHECK(frost_memcmp_and_randomize(shares[i].data, zeros68, sizeof(shares[i].data)) == 0);
+            CHECK(frost_memcmp_and_randomize(shares[i][j].data, zeros68, sizeof(shares[i][j].data)) == 0);
-    }
+        }
-    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 0));
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 0, 5, id_ptr));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 2));
+        for (j = 0; j < 5; j++) {
+            CHECK(frost_memcmp_and_randomize(shares[i][j].data, zeros68, sizeof(shares[i][j].data)) == 0);
+        }
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 3, 0, id_ptr));
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 3, 2, id_ptr));
+        CHECK_ILLEGAL(CTX, secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 3, 5, NULL));
+        for (j = 0; j < 5; j++) {
+            CHECK(frost_memcmp_and_randomize(shares[i][j].data, zeros68, sizeof(shares[i][j].data)) == 0);
+        }
 
-    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &pk, seed, 3, 5) == 1);
+        CHECK(secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 3, 5, id_ptr) == 1);
+    }
+
+    /* Share aggregation */
+    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
+            share_ptr[j] = &shares[j][i];
+        }
+        CHECK(secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, vss_ptr, 5, 3, id_ptr[i]) == 1);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, NULL, &agg_pk, share_ptr, vss_ptr, 5, 3, id_ptr[i]));
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], NULL, share_ptr, vss_ptr, 5, 3, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, NULL, vss_ptr, 5, 3, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, NULL, 5, 3, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+        /* TODO: fix test */
+        /* CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, invalid_vss_ptr, 5, 3, id_ptr[i])); */
+        /* CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0); */
+        /* CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0); */
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, vss_ptr, 5, 3, NULL));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, invalid_share_ptr, vss_ptr, 5, 3, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, vss_ptr, 0, 3, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, NULL, vss_ptr, 0, 3, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, vss_ptr, 5, 0, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+        CHECK_ILLEGAL(CTX, secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, NULL, 5, 0, id_ptr[i]));
+        CHECK(frost_memcmp_and_randomize(agg_share[i].data, zeros68, sizeof(agg_share[i].data)) == 0);
+        CHECK(frost_memcmp_and_randomize(agg_pk.data, zeros68, sizeof(agg_pk.data)) == 0);
+
+        CHECK(secp256k1_frost_share_agg(CTX, &agg_share[i], &agg_pk, share_ptr, vss_ptr, 5, 3, id_ptr[i]) == 1);
+    }
+
+    /* Share verification */
+    CHECK(secp256k1_frost_share_verify(CTX, 3, id_ptr[4], share_ptr[0], &vss_ptr[0]) == 1);
+    CHECK(secp256k1_frost_share_verify(CTX, 3, id_ptr[4], share_ptr[0], &vss_ptr[1]) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_share_verify(CTX, 3, NULL, share_ptr[0], &vss_ptr[0]));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_share_verify(CTX, 3, id_ptr[4], NULL, &vss_ptr[1]));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_share_verify(CTX, 3, id_ptr[4], &invalid_share, &vss_ptr[0]));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_share_verify(CTX, 3, id_ptr[4], share_ptr[0], NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_share_verify(CTX, 3, id_ptr[4], share_ptr[0], &invalid_vss_ptr[0]));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_share_verify(CTX, 0, id_ptr[4], share_ptr[0], &vss_ptr[0]));
+
+    CHECK(secp256k1_frost_share_verify(CTX, 3, id_ptr[4], share_ptr[0], &vss_ptr[0]) == 1);
+    CHECK(secp256k1_frost_share_verify(CTX, 3, id_ptr[4], share_ptr[1], &vss_ptr[1]) == 1);
+
+    /* Compute public verification share */
+    CHECK(secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 3, id_ptr[0], vss_ptr, 5) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, NULL, 3, id_ptr[0], vss_ptr, 5));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 3, NULL, vss_ptr, 5));
+    CHECK(frost_memcmp_and_randomize(pubshare[0].data, zeros68, sizeof(pubshare[0].data)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 3, id_ptr[0], NULL, 5));
+    CHECK(frost_memcmp_and_randomize(pubshare[0].data, zeros68, sizeof(pubshare[0].data)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 3, id_ptr[0], invalid_vss_ptr, 5));
+    CHECK(frost_memcmp_and_randomize(pubshare[0].data, zeros68, sizeof(pubshare[0].data)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 0, id_ptr[0], invalid_vss_ptr, 5));
+    CHECK(frost_memcmp_and_randomize(pubshare[0].data, zeros68, sizeof(pubshare[0].data)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 0, id_ptr[0], NULL, 5));
+    CHECK(frost_memcmp_and_randomize(pubshare[0].data, zeros68, sizeof(pubshare[0].data)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 3, id_ptr[0], invalid_vss_ptr, 0));
+    CHECK(frost_memcmp_and_randomize(pubshare[0].data, zeros68, sizeof(pubshare[0].data)) == 0);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 3, id_ptr[0], NULL, 0));
+    CHECK(frost_memcmp_and_randomize(pubshare[0].data, zeros68, sizeof(pubshare[0].data)) == 0);
+
+    CHECK(secp256k1_frost_compute_pubshare(CTX, &pubshare[0], 3, id_ptr[0], vss_ptr, 5) == 1);
+    CHECK(secp256k1_frost_compute_pubshare(CTX, &pubshare[1], 3, id_ptr[1], vss_ptr, 5) == 1);
+    CHECK(secp256k1_frost_compute_pubshare(CTX, &pubshare[2], 3, id_ptr[2], vss_ptr, 5) == 1);
 
     /* pubkey_get */
-    CHECK(secp256k1_frost_pubkey_get(CTX, &full_pk, &pk) == 1);
+    CHECK(secp256k1_frost_pubkey_get(CTX, &full_agg_pk, &agg_pk) == 1);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_get(CTX, NULL, &pk));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_get(CTX, NULL, &agg_pk));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_get(CTX, &full_pk, NULL));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_get(CTX, &full_agg_pk, NULL));
-    CHECK(secp256k1_memcmp_var(&full_pk, zeros68, sizeof(full_pk)) == 0);
+    CHECK(secp256k1_memcmp_var(&full_agg_pk, zeros68, sizeof(full_agg_pk)) == 0);
 
     /** Tweaking **/
 
     /* pubkey_tweak */
-    CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &pk) == 1);
+    CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &agg_pk) == 1);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_tweak(CTX, NULL, &pk));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_tweak(CTX, NULL, &agg_pk));
     CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, NULL));
     CHECK_ILLEGAL(CTX, secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &invalid_pk));
 
-    CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &pk) == 1);
+    CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &agg_pk) == 1);
 
     /* tweak_add */
     {
         int (*tweak_func[2]) (const secp256k1_context* ctx, secp256k1_pubkey *output_pubkey, secp256k1_frost_tweak_cache *tweak_cache, const unsigned char *tweak32);
         tweak_func[0] = secp256k1_frost_pubkey_ec_tweak_add;
         tweak_func[1] = secp256k1_frost_pubkey_xonly_tweak_add;
-        CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &pk) == 1);
+        CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &agg_pk) == 1);
         for (i = 0; i < 2; i++) {
             secp256k1_pubkey tmp_output_pk;
             secp256k1_frost_tweak_cache tmp_tweak_cache = tweak_cache;
@@ -248,31 +374,31 @@ void frost_api_tests(void) {
     }
 
     /** Session creation **/
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &pk, max64) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &agg_share[0], msg, &agg_pk, max64) == 1);
-    CHECK_ILLEGAL(STATIC_CTX, secp256k1_frost_nonce_gen(STATIC_CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &pk, max64));
+    CHECK_ILLEGAL(STATIC_CTX, secp256k1_frost_nonce_gen(STATIC_CTX, &secnonce[0], &pubnonce[0], session_id[0], &agg_share[0], msg, &agg_pk, max64));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, NULL, &pubnonce[0], session_id[0], &shares[0], msg, &pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, NULL, &pubnonce[0], session_id[0], &agg_share[0], msg, &agg_pk, max64));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], NULL, session_id[0], &shares[0], msg, &pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], NULL, session_id[0], &agg_share[0], msg, &agg_pk, max64));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], NULL, &shares[0], msg, &pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], NULL, &agg_share[0], msg, &agg_pk, max64));
     CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
     /* no seckey and session_id is 0 */
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], zeros68, NULL, msg, &pk, max64) == 0);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], zeros68, NULL, msg, &agg_pk, max64) == 0);
     CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
     /* session_id 0 is fine when a seckey is provided */
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], zeros68, &shares[0], msg, &pk, max64) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], zeros68, &agg_share[0], msg, &agg_pk, max64) == 1);
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], NULL, msg, &pk, max64) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], NULL, msg, &agg_pk, max64) == 1);
-    /* invalid share */
+    /* invalid agg_share */
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &invalid_share, msg, &pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &invalid_share, msg, &agg_pk, max64));
     CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], NULL, &pk, max64) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &agg_share[0], NULL, &agg_pk, max64) == 1);
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, NULL, max64) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &agg_share[0], msg, NULL, max64) == 1);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &invalid_pk, max64));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &agg_share[0], msg, &invalid_pk, max64));
     CHECK(frost_memcmp_and_randomize(secnonce[0].data, zeros68, sizeof(secnonce[0].data)) == 0);
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &shares[0], msg, &pk, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], &agg_share[0], msg, &agg_pk, NULL) == 1);
 
     /* Every in-argument except session_id can be NULL */
     CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[0], &pubnonce[0], session_id[0], NULL, NULL, NULL, NULL) == 1);
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[1], &pubnonce[1], session_id[1], &shares[1], NULL, NULL, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[1], &pubnonce[1], session_id[1], &agg_share[1], NULL, NULL, NULL) == 1);
-    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[2], &pubnonce[2], session_id[2], &shares[2], NULL, NULL, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[2], &pubnonce[2], session_id[2], &agg_share[2], NULL, NULL, NULL) == 1);
 
     /** Serialize and parse public nonces **/
     CHECK_ILLEGAL(CTX, secp256k1_frost_pubnonce_serialize(CTX, NULL, &pubnonce[0]));
@@ -297,51 +423,50 @@ void frost_api_tests(void) {
     }
 
     /** Process nonces **/
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, &adaptor) == 1);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, NULL, pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, NULL, pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], NULL, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], NULL, 3, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 0, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 0, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], invalid_pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], invalid_pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, NULL, &pk, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, NULL, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, NULL, ids[0], ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, NULL, id_ptr[0], id_ptr, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, 0, ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, NULL, id_ptr, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], invalid_ids, &tweak_cache, &adaptor));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], NULL, &tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], NULL, &tweak_cache, &adaptor));
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, NULL, &adaptor) == 1);
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, NULL, &adaptor) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, &invalid_tweak_cache, &adaptor));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &invalid_tweak_cache, &adaptor));
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, NULL) == 1);
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, NULL) == 1);
+    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, (secp256k1_pubkey *)&invalid_pk));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, (secp256k1_pubkey *)&invalid_pk));
 
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &pk, ids[0], ids, &tweak_cache, &adaptor) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[0], id_ptr, &tweak_cache, &adaptor) == 1);
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[1], pubnonce_ptr, 3, msg, &pk, ids[1], ids, &tweak_cache, &adaptor) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[1], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[1], id_ptr, &tweak_cache, &adaptor) == 1);
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[2], pubnonce_ptr, 3, msg, &pk, ids[2], ids, &tweak_cache, &adaptor) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[2], pubnonce_ptr, 3, msg, &agg_pk, id_ptr[2], id_ptr, &tweak_cache, &adaptor) == 1);
 
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
-    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &agg_share[0], &session[0], &tweak_cache) == 1);
     /* The secnonce is set to 0 and subsequent signing attempts fail */
     CHECK(secp256k1_memcmp_var(&secnonce_tmp, zeros68, sizeof(secnonce_tmp)) == 0);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &agg_share[0], &session[0], &tweak_cache));
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, NULL, &secnonce_tmp, &shares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, NULL, &secnonce_tmp, &agg_share[0], &session[0], &tweak_cache));
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], NULL, &shares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], NULL, &agg_share[0], &session[0], &tweak_cache));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &invalid_secnonce, &shares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &invalid_secnonce, &agg_share[0], &session[0], &tweak_cache));
     CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, NULL, &session[0], &tweak_cache));
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
     CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &invalid_share, &session[0], &tweak_cache));
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], NULL, &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &agg_share[0], NULL, &tweak_cache));
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &invalid_session, &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &agg_share[0], &invalid_session, &tweak_cache));
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
-    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], NULL) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &agg_share[0], &session[0], NULL) == 1);
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &shares[0], &session[0], &invalid_tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce_tmp, &agg_share[0], &session[0], &invalid_tweak_cache));
     memcpy(&secnonce_tmp, &secnonce[0], sizeof(secnonce_tmp));
 
-    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce[0], &shares[0], &session[0], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce[0], &agg_share[0], &session[0], &tweak_cache) == 1);
-    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[1], &secnonce[1], &shares[1], &session[1], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[1], &secnonce[1], &agg_share[1], &session[1], &tweak_cache) == 1);
-    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[2], &secnonce[2], &shares[2], &session[2], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[2], &secnonce[2], &agg_share[2], &session[2], &tweak_cache) == 1);
 
     CHECK(secp256k1_frost_partial_sig_serialize(CTX, buf, &partial_sig[0]) == 1);
     CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_serialize(CTX, NULL, &partial_sig[0]));
@@ -360,22 +485,22 @@ void frost_api_tests(void) {
     }
 
     /** Partial signature verification */
-    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshare[0], &session[0], &tweak_cache) == 1);
-    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[1], &pubnonce[0], &pubshares[0], &session[0], &tweak_cache) == 0);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[1], &pubnonce[0], &pubshare[0], &session[0], &tweak_cache) == 0);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, NULL, &pubnonce[0], &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, NULL, &pubnonce[0], &pubshare[0], &session[0], &tweak_cache));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &invalid_partial_sig, &pubnonce[0], &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &invalid_partial_sig, &pubnonce[0], &pubshare[0], &session[0], &tweak_cache));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], NULL, &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], NULL, &pubshare[0], &session[0], &tweak_cache));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &invalid_pubnonce, &pubshares[0], &session[0], &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &invalid_pubnonce, &pubshare[0], &session[0], &tweak_cache));
     CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], NULL, &session[0], &tweak_cache));
     CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &invalid_vss_pk, &session[0], &tweak_cache));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], NULL, &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshare[0], NULL, &tweak_cache));
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &invalid_session, &tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshare[0], &invalid_session, &tweak_cache));
-    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], NULL) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshare[0], &session[0], NULL) == 1);
-    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], &invalid_tweak_cache));
+    CHECK_ILLEGAL(CTX, secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshare[0], &session[0], &invalid_tweak_cache));
 
-    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshares[0], &session[0], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[0], &pubnonce[0], &pubshare[0], &session[0], &tweak_cache) == 1);
-    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[1], &pubnonce[1], &pubshares[1], &session[1], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[1], &pubnonce[1], &pubshare[1], &session[1], &tweak_cache) == 1);
-    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[2], &pubnonce[2], &pubshares[2], &session[2], &tweak_cache) == 1);
+    CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[2], &pubnonce[2], &pubshare[2], &session[2], &tweak_cache) == 1);
 
     /** Signature aggregation and verification */
     CHECK(secp256k1_frost_partial_sig_agg(CTX, pre_sig, &session[0], partial_sig_ptr, 3) == 1);
@@ -405,10 +530,10 @@ void frost_api_tests(void) {
     /* sig and pre_sig argument point to the same location */
     memcpy(final_sig, pre_sig, sizeof(final_sig));
     CHECK(secp256k1_frost_adapt(CTX, final_sig, final_sig, sec_adaptor, nonce_parity) == 1);
-    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &pk) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &agg_pk) == 1);
 
     CHECK(secp256k1_frost_adapt(CTX, final_sig, pre_sig, sec_adaptor, nonce_parity) == 1);
-    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &pk) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), &agg_pk) == 1);
 
     /** Secret adaptor can be extracted from signature */
     CHECK(secp256k1_frost_extract_adaptor(CTX, sec_adaptor1, final_sig, pre_sig, nonce_parity) == 1);
@@ -482,9 +607,37 @@ void frost_nonce_test(void) {
     }
 }
 
+void frost_sha256_tag_test_internal(secp256k1_sha256 *sha_tagged, unsigned char *tag, size_t taglen) {
+    secp256k1_sha256 sha;
+    unsigned char buf[32];
+    unsigned char buf2[32];
+    size_t i;
+
+    secp256k1_sha256_initialize(&sha);
+    secp256k1_sha256_write(&sha, tag, taglen);
+    secp256k1_sha256_finalize(&sha, buf);
+    /* buf = SHA256(tag) */
+
+    secp256k1_sha256_initialize(&sha);
+    secp256k1_sha256_write(&sha, buf, 32);
+    secp256k1_sha256_write(&sha, buf, 32);
+    /* Is buffer fully consumed? */
+    CHECK((sha.bytes & 0x3F) == 0);
+
+    /* Compare with tagged SHA */
+    for (i = 0; i < 8; i++) {
+        CHECK(sha_tagged->s[i] == sha.s[i]);
+    }
+    secp256k1_sha256_write(&sha, buf, 32);
+    secp256k1_sha256_write(sha_tagged, buf, 32);
+    secp256k1_sha256_finalize(&sha, buf);
+    secp256k1_sha256_finalize(sha_tagged, buf2);
+    CHECK(secp256k1_memcmp_var(buf, buf2, 32) == 0);
+}
+
 /* Attempts to create a signature for the aggregate public key using given secret
  * keys and tweak_cache. */
-void frost_tweak_test_helper(const secp256k1_xonly_pubkey* pk, const secp256k1_frost_share *sr0, const secp256k1_frost_share *sr1, const secp256k1_frost_share *sr2, secp256k1_frost_tweak_cache *tweak_cache, const size_t *ids, const secp256k1_pubkey *sr_pk0, const secp256k1_pubkey *sr_pk1, const secp256k1_pubkey *sr_pk2) {
+void frost_tweak_test_helper(const secp256k1_xonly_pubkey* agg_pk, const secp256k1_frost_share *sr0, const secp256k1_frost_share *sr1, const secp256k1_frost_share *sr2, secp256k1_frost_tweak_cache *tweak_cache, const unsigned char * const* ids33, const secp256k1_pubkey *sr_pk0, const secp256k1_pubkey *sr_pk1, const secp256k1_pubkey *sr_pk2) {
     unsigned char session_id[3][32];
     unsigned char msg[32];
     secp256k1_frost_secnonce secnonce[3];
@@ -509,9 +662,9 @@ void frost_tweak_test_helper(const secp256k1_xonly_pubkey* pk, const secp256k1_f
     CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[1], &pubnonce[1], session_id[1], sr1, NULL, NULL, NULL) == 1);
     CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[2], &pubnonce[2], session_id[2], sr2, NULL, NULL, NULL) == 1);
 
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, pk, ids[0], ids, tweak_cache, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[0], pubnonce_ptr, 3, msg, agg_pk, ids33[0], ids33, tweak_cache, NULL) == 1);
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[1], pubnonce_ptr, 3, msg, pk, ids[1], ids, tweak_cache, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[1], pubnonce_ptr, 3, msg, agg_pk, ids33[1], ids33, tweak_cache, NULL) == 1);
-    CHECK(secp256k1_frost_nonce_process(CTX, &session[2], pubnonce_ptr, 3, msg, pk, ids[2], ids, tweak_cache, NULL) == 1);
+    CHECK(secp256k1_frost_nonce_process(CTX, &session[2], pubnonce_ptr, 3, msg, agg_pk, ids33[2], ids33, tweak_cache, NULL) == 1);
 
 
     CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[0], &secnonce[0], sr0, &session[0], tweak_cache) == 1);
@@ -523,31 +676,51 @@ void frost_tweak_test_helper(const secp256k1_xonly_pubkey* pk, const secp256k1_f
     CHECK(secp256k1_frost_partial_sig_verify(CTX, &partial_sig[2], &pubnonce[2], sr_pk2, &session[2], tweak_cache) == 1);
 
     CHECK(secp256k1_frost_partial_sig_agg(CTX, final_sig, &session[0], partial_sig_ptr, 3) == 1);
-    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), pk) == 1);
+    CHECK(secp256k1_schnorrsig_verify(CTX, final_sig, msg, sizeof(msg), agg_pk) == 1);
 }
 
 /* Create aggregate public key P[0], tweak multiple times (using xonly and
  * ordinary tweaking) and test signing. */
 void frost_tweak_test(void) {
-    secp256k1_pubkey pubshares[5];
+    unsigned char sk[5][32];
+    secp256k1_pubkey pubshare[5];
     secp256k1_frost_tweak_cache tweak_cache;
     enum { N_TWEAKS = 8 };
     secp256k1_pubkey P[N_TWEAKS + 1];
     secp256k1_xonly_pubkey P_xonly[N_TWEAKS + 1];
-    unsigned char seed[32];
+    unsigned char seed[5][32];
-    secp256k1_frost_share shares[5];
+    secp256k1_pubkey vss_commitment[5][3];
-    int i;
+    const secp256k1_pubkey *vss_ptr[5];
-    size_t ids[5];
+    unsigned char pok[5][64];
-
+    secp256k1_frost_share shares[5][5];
-    secp256k1_testrand256(seed);
+    const secp256k1_frost_share *share_ptr[5];
+    secp256k1_frost_share agg_share[5];
+    int i, j;
+    unsigned char id[5][33];
+    const unsigned char *id_ptr[5];
 
     /* Key Setup */
     for (i = 0; i < 5; i++) {
-        ids[i] = i + 1;
+        secp256k1_testrand256(seed[i]);
-    }
+        secp256k1_testrand256(sk[i]);
-    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, &P_xonly[0], seed, 3, 5) == 1);
+        vss_ptr[i] = vss_commitment[i];
+        id_ptr[i] = id[i];
 
-    frost_tweak_test_helper(&P_xonly[0], &shares[0], &shares[1], &shares[2], NULL, ids, &pubshares[0], &pubshares[1], &pubshares[2]);
+        CHECK(frost_create_pk(id[i], sk[i]));
+    }
+    for (i = 0; i < 5; i++) {
+        CHECK(secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 3, 5, id_ptr) == 1);
+    }
+    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
+            share_ptr[j] = &shares[j][i];
+            CHECK(secp256k1_frost_share_verify(CTX, 3, id_ptr[i], share_ptr[j], &vss_ptr[j]) == 1);
+            CHECK(secp256k1_frost_compute_pubshare(CTX, &pubshare[j], 3, id_ptr[j], vss_ptr, 5) == 1);
+        }
+        CHECK(secp256k1_frost_share_agg(CTX, &agg_share[i], &P_xonly[0], share_ptr, vss_ptr, 5, 3, id_ptr[i]) == 1);
+    }
+
+    frost_tweak_test_helper(&P_xonly[0], &agg_share[0], &agg_share[1], &agg_share[2], NULL, id_ptr, &pubshare[0], &pubshare[1], &pubshare[2]);
     CHECK(secp256k1_frost_pubkey_get(CTX, &P[0], &P_xonly[0]));
     CHECK(secp256k1_frost_pubkey_tweak(CTX, &tweak_cache, &P_xonly[0]) == 1);
 
@@ -579,22 +752,37 @@ void frost_tweak_test(void) {
             CHECK(secp256k1_memcmp_var(&tmp_key, &P[i], sizeof(tmp_key)) == 0);
         }
         /* Test signing for P[i] */
-        frost_tweak_test_helper(&P_xonly[i], &shares[0], &shares[1], &shares[2], &tweak_cache, ids, &pubshares[0], &pubshares[1], &pubshares[2]);
+        frost_tweak_test_helper(&P_xonly[i], &agg_share[0], &agg_share[1], &agg_share[2], &tweak_cache, id_ptr, &pubshare[0], &pubshare[1], &pubshare[2]);
     }
 }
 
 /* Performs a FROST DKG */
-void frost_dkg_test_helper(secp256k1_frost_share *shares, secp256k1_xonly_pubkey *pk) {
+void frost_dkg_test_helper(secp256k1_frost_share *agg_share, secp256k1_xonly_pubkey *agg_pk, const unsigned char * const* ids33) {
-    unsigned char seed[32];
+    secp256k1_pubkey vss_commitment[5][3];
-    secp256k1_pubkey pubshares[5];
+    const secp256k1_pubkey *vss_ptr[5];
+    unsigned char pok[5][64];
+    unsigned char seed[5][32];
+    secp256k1_frost_share shares[5][5];
+    const secp256k1_frost_share *share_ptr[5];
+    int i, j;
 
-    secp256k1_testrand256(seed);
+    for (i = 0; i < 5; i++) {
-
+        secp256k1_testrand256(seed[i]);
-    CHECK(secp256k1_frost_shares_trusted_gen(CTX, shares, pubshares, pk, seed, 3, 5) == 1);
+        vss_ptr[i] = vss_commitment[i];
+    }
+    for (i = 0; i < 5; i++) {
+        CHECK(secp256k1_frost_shares_gen(CTX, shares[i], vss_commitment[i], pok[i], seed[i], 3, 5, ids33) == 1);
+    }
+    for (i = 0; i < 5; i++) {
+        for (j = 0; j < 5; j++) {
+            share_ptr[j] = &shares[j][i];
+        }
+        CHECK(secp256k1_frost_share_agg(CTX, &agg_share[i], agg_pk, share_ptr, vss_ptr, 5, 3, ids33[i]) == 1);
+    }
 }
 
 /* Signs a message with a FROST keypair */
-int frost_sign_test_helper(unsigned char *final_sig, const secp256k1_frost_share *share, const secp256k1_xonly_pubkey *pk, const unsigned char *msg, const secp256k1_pubkey *adaptor) {
+int frost_sign_test_helper(unsigned char *final_sig, const secp256k1_frost_share *agg_share, const secp256k1_xonly_pubkey *agg_pk, const unsigned char * const* ids33, const unsigned char *msg, const secp256k1_pubkey *adaptor) {
     unsigned char session_id[3][32];
     secp256k1_frost_secnonce secnonce[3];
     secp256k1_frost_pubnonce pubnonce[3];
@@ -605,22 +793,20 @@ int frost_sign_test_helper(unsigned char *final_sig, const secp256k1_frost_share
     int i;
     int nonce_parity;
     secp256k1_frost_session_internal session_i;
-    size_t ids[5];
 
     for (i = 0; i < 3; i++) {
         pubnonce_ptr[i] = &pubnonce[i];
         partial_sig_ptr[i] = &partial_sig[i];
-        ids[i] = i + 1;
     }
 
     for (i = 0; i < 3; i++) {
         secp256k1_testrand256(session_id[i]);
 
-        CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[i], &pubnonce[i], session_id[i], &share[i], NULL, NULL, NULL) == 1);
+        CHECK(secp256k1_frost_nonce_gen(CTX, &secnonce[i], &pubnonce[i], session_id[i], agg_share, NULL, NULL, NULL) == 1);
     }
     for (i = 0; i < 3; i++) {
-        CHECK(secp256k1_frost_nonce_process(CTX, &session, pubnonce_ptr, 3, msg, pk, i + 1, ids, NULL, adaptor) == 1);
+        CHECK(secp256k1_frost_nonce_process(CTX, &session, pubnonce_ptr, 3, msg, agg_pk, ids33[i], ids33, NULL, adaptor) == 1);
-        CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[i], &secnonce[i], &share[i], &session, NULL) == 1);
+        CHECK(secp256k1_frost_partial_sign(CTX, &partial_sig[i], &secnonce[i], &agg_share[i], &session, NULL) == 1);
     }
     CHECK(secp256k1_frost_partial_sig_agg(CTX, final_sig, &session, partial_sig_ptr, 3) == 1);
 
@@ -638,10 +824,12 @@ void frost_rand_scalar(secp256k1_scalar *scalar) {
 }
 
 void frost_multi_hop_lock_tests(void) {
-    secp256k1_frost_share share_a[5];
+    secp256k1_frost_share agg_share_a[5];
-    secp256k1_frost_share share_b[5];
+    secp256k1_frost_share agg_share_b[5];
     secp256k1_xonly_pubkey agg_pk_a;
     secp256k1_xonly_pubkey agg_pk_b;
+    unsigned char sk_a[5][32];
+    unsigned char sk_b[5][32];
     unsigned char asig_ab[64];
     unsigned char asig_bc[64];
     unsigned char pop[32];
@@ -657,12 +845,29 @@ void frost_multi_hop_lock_tests(void) {
     unsigned char sig_bc[64];
     int nonce_parity_ab;
     int nonce_parity_bc;
+    int i;
+    unsigned char id_a[5][33];
+    const unsigned char *id_ptr_a[5];
+    unsigned char id_b[5][33];
+    const unsigned char *id_ptr_b[5];
 
     /* Alice DKG */
-    frost_dkg_test_helper(share_a, &agg_pk_a);
+    for (i = 0; i < 5; i++) {
+        secp256k1_testrand256(sk_a[i]);
+        id_ptr_a[i] = id_a[i];
+
+        CHECK(frost_create_pk(id_a[i], sk_a[i]));
+    }
+    frost_dkg_test_helper(agg_share_a, &agg_pk_a, id_ptr_a);
 
     /* Bob DKG */
-    frost_dkg_test_helper(share_b, &agg_pk_b);
+    for (i = 0; i < 5; i++) {
+        secp256k1_testrand256(sk_b[i]);
+        id_ptr_b[i] = id_b[i];
+
+        CHECK(frost_create_pk(id_b[i], sk_b[i]));
+    }
+    frost_dkg_test_helper(agg_share_b, &agg_pk_b, id_ptr_b);
 
     /* Carol setup */
     /* Proof of payment */
@@ -683,13 +888,13 @@ void frost_multi_hop_lock_tests(void) {
     CHECK(secp256k1_eckey_pubkey_tweak_add(&r_ge, &tp));
     secp256k1_pubkey_save(&r, &r_ge);
     /* Encrypt Alice's signature with the left lock as the encryption key */
-    nonce_parity_ab = frost_sign_test_helper(asig_ab, share_a, &agg_pk_a, tx_ab, &l);
+    nonce_parity_ab = frost_sign_test_helper(asig_ab, agg_share_a, &agg_pk_a, id_ptr_a, tx_ab, &l);
 
     /* Bob setup */
     CHECK(secp256k1_frost_verify_adaptor(CTX, asig_ab, tx_ab, &agg_pk_a, &l, nonce_parity_ab) == 1);
     secp256k1_testrand256(tx_bc);
     /* Encrypt Bob's signature with the right lock as the encryption key */
-    nonce_parity_bc = frost_sign_test_helper(asig_bc, share_b, &agg_pk_b, tx_bc, &r);
+    nonce_parity_bc = frost_sign_test_helper(asig_bc, agg_share_b, &agg_pk_b, id_ptr_b, tx_bc, &r);
 
     /* Carol decrypt */
     CHECK(secp256k1_frost_verify_adaptor(CTX, asig_bc, tx_bc, &agg_pk_b, &r, nonce_parity_bc) == 1);

src/modules/generator/main_impl.h

@@ -276,7 +276,6 @@ static void secp256k1_pedersen_commitment_save(secp256k1_pedersen_commitment* co
 
 int secp256k1_pedersen_commitment_parse(const secp256k1_context* ctx, secp256k1_pedersen_commitment* commit, const unsigned char *input) {
     secp256k1_fe x;
-    secp256k1_ge ge;
 
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(commit != NULL);
@@ -285,28 +284,20 @@ int secp256k1_pedersen_commitment_parse(const secp256k1_context* ctx, secp256k1_
 
     if ((input[0] & 0xFE) != 8 ||
         !secp256k1_fe_set_b32_limit(&x, &input[1]) ||
-        !secp256k1_ge_set_xquad(&ge, &x)) {
+        !secp256k1_ge_x_on_curve_var(&x)) {
         return 0;
     }
-    if (input[0] & 1) {
+
-        secp256k1_ge_neg(&ge, &ge);
+    memcpy(commit->data, input, 33);
-    }
-    secp256k1_pedersen_commitment_save(commit, &ge);
     return 1;
 }
 
 int secp256k1_pedersen_commitment_serialize(const secp256k1_context* ctx, unsigned char *output, const secp256k1_pedersen_commitment* commit) {
-    secp256k1_ge ge;
-
     VERIFY_CHECK(ctx != NULL);
     ARG_CHECK(output != NULL);
     ARG_CHECK(commit != NULL);
 
-    secp256k1_pedersen_commitment_load(&ge, commit);
+    memcpy(output, commit->data, 33);
-
-    output[0] = 9 ^ secp256k1_fe_is_square_var(&ge.y);
-    secp256k1_fe_normalize_var(&ge.x);
-    secp256k1_fe_get_b32(&output[1], &ge.x);
     return 1;
 }
 

src/modules/generator/tests_impl.h

@@ -264,7 +264,13 @@ static void test_pedersen(void) {
     }
     CHECK(secp256k1_pedersen_blind_sum(CTX, &blinds[(total - 1) * 32], bptr, total - 1, inputs));
     for (i = 0; i < total; i++) {
+        unsigned char result[33];
+        secp256k1_pedersen_commitment parse;
+
         CHECK(secp256k1_pedersen_commit(CTX, &commits[i], &blinds[i * 32], values[i], secp256k1_generator_h));
+        CHECK(secp256k1_pedersen_commitment_serialize(CTX, result, &commits[i]));
+        CHECK(secp256k1_pedersen_commitment_parse(CTX, &parse, result));
+        CHECK(secp256k1_memcmp_var(&commits[i], &parse, 33) == 0);
     }
     CHECK(secp256k1_pedersen_verify_tally(CTX, cptr, inputs, &cptr[inputs], outputs));
     CHECK(secp256k1_pedersen_verify_tally(CTX, &cptr[inputs], outputs, cptr, inputs));

src/secp256k1.c

@@ -889,10 +889,6 @@ static int secp256k1_ge_parse_ext(secp256k1_ge* ge, const unsigned char *in33) {
 # include "modules/ecdsa_adaptor/main_impl.h"
 #endif
 
-#ifdef ENABLE_MODULE_FROST
-# include "modules/frost/main_impl.h"
-#endif
-
 #ifdef ENABLE_MODULE_MUSIG
 # include "modules/musig/main_impl.h"
 #endif
@@ -912,3 +908,7 @@ static int secp256k1_ge_parse_ext(secp256k1_ge* ge, const unsigned char *in33) {
 #ifdef ENABLE_MODULE_SURJECTIONPROOF
 # include "modules/surjection/main_impl.h"
 #endif
+
+#ifdef ENABLE_MODULE_FROST
+# include "modules/frost/main_impl.h"
+#endif