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[RANGEPROOF BREAK] Use quadratic residue for tie break and modularity cleanup

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Switch to secp256k1_pedersen_commitment by Andrew Poelstra.
Switch to quadratic residue based disambiguation by Pieter Wuille.
This commit is contained in:
Andrew Poelstra
2016-07-04 13:04:57 +00:00
committed by Tim Ruffing
parent 16618fcd8d
commit a88db4a744
11 changed files with 285 additions and 174 deletions
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87
src/modules/rangeproof/main_impl.h
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@@ -7,16 +7,48 @@
#ifndef SECP256K1_MODULE_RANGEPROOF_MAIN
#define SECP256K1_MODULE_RANGEPROOF_MAIN
#include "group.h"
#include "modules/rangeproof/pedersen_impl.h"
#include "modules/rangeproof/borromean_impl.h"
#include "modules/rangeproof/rangeproof_impl.h"
/* Generates a pedersen commitment: *commit = blind * G + value * G2. The commitment is 33 bytes, the blinding factor is 32 bytes.*/
int secp256k1_pedersen_commit(const secp256k1_context* ctx, unsigned char *commit, unsigned char *blind, uint64_t value) {
static void secp256k1_pedersen_commitment_load(secp256k1_ge* ge, const secp256k1_pedersen_commitment* commit) {
secp256k1_fe fe;
secp256k1_fe_set_b32(&fe, &commit->data[1]);
secp256k1_ge_set_xquad(ge, &fe);
if (commit->data[0] & 1) {
secp256k1_ge_neg(ge, ge);
}
}
static void secp256k1_pedersen_commitment_save(secp256k1_pedersen_commitment* commit, secp256k1_ge* ge) {
secp256k1_fe_normalize(&ge->x);
secp256k1_fe_get_b32(&commit->data[1], &ge->x);
commit->data[0] = 9 ^ secp256k1_fe_is_quad_var(&ge->y);
}
int secp256k1_pedersen_commitment_parse(const secp256k1_context* ctx, secp256k1_pedersen_commitment* commit, const unsigned char *input) {
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(commit != NULL);
ARG_CHECK(input != NULL);
memcpy(commit->data, input, sizeof(commit->data));
return 1;
}
int secp256k1_pedersen_commitment_serialize(const secp256k1_context* ctx, unsigned char *output, const secp256k1_pedersen_commitment* commit) {
VERIFY_CHECK(ctx != NULL);
ARG_CHECK(output != NULL);
ARG_CHECK(commit != NULL);
memcpy(output, commit->data, sizeof(commit->data));
return 1;
}
/* Generates a pedersen commitment: *commit = blind * G + value * G2. The blinding factor is 32 bytes.*/
int secp256k1_pedersen_commit(const secp256k1_context* ctx, secp256k1_pedersen_commitment *commit, const unsigned char *blind, uint64_t value) {
secp256k1_gej rj;
secp256k1_ge r;
secp256k1_scalar sec;
size_t sz;
int overflow;
int ret = 0;
ARG_CHECK(ctx != NULL);
@@ -28,8 +60,8 @@ int secp256k1_pedersen_commit(const secp256k1_context* ctx, unsigned char *commi
secp256k1_pedersen_ecmult(&ctx->ecmult_gen_ctx, &rj, &sec, value);
if (!secp256k1_gej_is_infinity(&rj)) {
secp256k1_ge_set_gej(&r, &rj);
sz = 33;
ret = secp256k1_eckey_pubkey_serialize(&r, commit, &sz, 1);
secp256k1_pedersen_commitment_save(commit, &r);
ret = 1;
}
secp256k1_gej_clear(&rj);
secp256k1_ge_clear(&r);
@@ -41,10 +73,10 @@ int secp256k1_pedersen_commit(const secp256k1_context* ctx, unsigned char *commi
/** Takes a list of n pointers to 32 byte blinding values, the first negs of which are treated with positive sign and the rest
* negative, then calculates an additional blinding value that adds to zero.
*/
int secp256k1_pedersen_blind_sum(const secp256k1_context* ctx, unsigned char *blind_out, const unsigned char * const *blinds, int n, int npositive) {
int secp256k1_pedersen_blind_sum(const secp256k1_context* ctx, unsigned char *blind_out, const unsigned char * const *blinds, size_t n, size_t npositive) {
secp256k1_scalar acc;
secp256k1_scalar x;
int i;
size_t i;
int overflow;
ARG_CHECK(ctx != NULL);
ARG_CHECK(blind_out != NULL);
@@ -66,12 +98,11 @@ int secp256k1_pedersen_blind_sum(const secp256k1_context* ctx, unsigned char *bl
return 1;
}
/* Takes two list of 33-byte commitments and sums the first set and subtracts the second and verifies that they sum to excess. */
int secp256k1_pedersen_verify_tally(const secp256k1_context* ctx, const unsigned char * const *commits, int pcnt,
const unsigned char * const *ncommits, int ncnt, int64_t excess) {
/* Takes two lists of commitments and sums the first set and subtracts the second and verifies that they sum to excess. */
int secp256k1_pedersen_verify_tally(const secp256k1_context* ctx, const secp256k1_pedersen_commitment * const* commits, size_t pcnt, const secp256k1_pedersen_commitment * const* ncommits, size_t ncnt, int64_t excess) {
secp256k1_gej accj;
secp256k1_ge add;
int i;
size_t i;
ARG_CHECK(ctx != NULL);
ARG_CHECK(!pcnt || (commits != NULL));
ARG_CHECK(!ncnt || (ncommits != NULL));
@@ -87,24 +118,20 @@ int secp256k1_pedersen_verify_tally(const secp256k1_context* ctx, const unsigned
}
}
for (i = 0; i < ncnt; i++) {
if (!secp256k1_eckey_pubkey_parse(&add, ncommits[i], 33)) {
return 0;
}
secp256k1_pedersen_commitment_load(&add, ncommits[i]);
secp256k1_gej_add_ge_var(&accj, &accj, &add, NULL);
}
secp256k1_gej_neg(&accj, &accj);
for (i = 0; i < pcnt; i++) {
if (!secp256k1_eckey_pubkey_parse(&add, commits[i], 33)) {
return 0;
}
secp256k1_pedersen_commitment_load(&add, commits[i]);
secp256k1_gej_add_ge_var(&accj, &accj, &add, NULL);
}
return secp256k1_gej_is_infinity(&accj);
}
int secp256k1_rangeproof_info(const secp256k1_context* ctx, int *exp, int *mantissa,
uint64_t *min_value, uint64_t *max_value, const unsigned char *proof, int plen) {
int offset;
uint64_t *min_value, uint64_t *max_value, const unsigned char *proof, size_t plen) {
size_t offset;
uint64_t scale;
ARG_CHECK(exp != NULL);
ARG_CHECK(mantissa != NULL);
@@ -117,9 +144,10 @@ int secp256k1_rangeproof_info(const secp256k1_context* ctx, int *exp, int *manti
}
int secp256k1_rangeproof_rewind(const secp256k1_context* ctx,
unsigned char *blind_out, uint64_t *value_out, unsigned char *message_out, int *outlen, const unsigned char *nonce,
unsigned char *blind_out, uint64_t *value_out, unsigned char *message_out, size_t *outlen, const unsigned char *nonce,
uint64_t *min_value, uint64_t *max_value,
const unsigned char *commit, const unsigned char *proof, int plen) {
const secp256k1_pedersen_commitment *commit, const unsigned char *proof, size_t plen) {
secp256k1_ge commitp;
ARG_CHECK(ctx != NULL);
ARG_CHECK(commit != NULL);
ARG_CHECK(proof != NULL);
@@ -127,24 +155,28 @@ int secp256k1_rangeproof_rewind(const secp256k1_context* ctx,
ARG_CHECK(max_value != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
secp256k1_pedersen_commitment_load(&commitp, commit);
return secp256k1_rangeproof_verify_impl(&ctx->ecmult_ctx, &ctx->ecmult_gen_ctx,
blind_out, value_out, message_out, outlen, nonce, min_value, max_value, commit, proof, plen);
blind_out, value_out, message_out, outlen, nonce, min_value, max_value, &commitp, proof, plen);
}
int secp256k1_rangeproof_verify(const secp256k1_context* ctx, uint64_t *min_value, uint64_t *max_value,
const unsigned char *commit, const unsigned char *proof, int plen) {
const secp256k1_pedersen_commitment *commit, const unsigned char *proof, size_t plen) {
secp256k1_ge commitp;
ARG_CHECK(ctx != NULL);
ARG_CHECK(commit != NULL);
ARG_CHECK(proof != NULL);
ARG_CHECK(min_value != NULL);
ARG_CHECK(max_value != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
secp256k1_pedersen_commitment_load(&commitp, commit);
return secp256k1_rangeproof_verify_impl(&ctx->ecmult_ctx, NULL,
NULL, NULL, NULL, NULL, NULL, min_value, max_value, commit, proof, plen);
NULL, NULL, NULL, NULL, NULL, min_value, max_value, &commitp, proof, plen);
}
int secp256k1_rangeproof_sign(const secp256k1_context* ctx, unsigned char *proof, int *plen, uint64_t min_value,
const unsigned char *commit, const unsigned char *blind, const unsigned char *nonce, int exp, int min_bits, uint64_t value){
int secp256k1_rangeproof_sign(const secp256k1_context* ctx, unsigned char *proof, size_t *plen, uint64_t min_value,
const secp256k1_pedersen_commitment *commit, const unsigned char *blind, const unsigned char *nonce, int exp, int min_bits, uint64_t value){
secp256k1_ge commitp;
ARG_CHECK(ctx != NULL);
ARG_CHECK(proof != NULL);
ARG_CHECK(plen != NULL);
@@ -153,8 +185,9 @@ int secp256k1_rangeproof_sign(const secp256k1_context* ctx, unsigned char *proof
ARG_CHECK(nonce != NULL);
ARG_CHECK(secp256k1_ecmult_context_is_built(&ctx->ecmult_ctx));
ARG_CHECK(secp256k1_ecmult_gen_context_is_built(&ctx->ecmult_gen_ctx));
secp256k1_pedersen_commitment_load(&commitp, commit);
return secp256k1_rangeproof_sign_impl(&ctx->ecmult_ctx, &ctx->ecmult_gen_ctx,
proof, plen, min_value, commit, blind, nonce, exp, min_bits, value);
proof, plen, min_value, &commitp, blind, nonce, exp, min_bits, value);
}
#endif