Port the two sub-protocol layers of the ChillDKG reference
implementation (bip-frost-dkg v0.3.0-dev, upstream commit
a91896883f85b159415ecf298d5e844879af112d) to C, keeping the same
function decomposition as simplpedpop.py / encpedpop.py so the code
stays diffable against the reference.
simplpedpop.h / simplpedpop_impl.h (mirrors simplpedpop.py):
- simplpedpop_participant_step1: VSS coefficient generation and
commitment, per-participant shares, proof of possession. The PoP is
a BIP-340 signature with custom tag prefix "BIP DKG/pop message"
over u32be(participant_id), signed with the constant coefficient
f(0), using TH("BIP DKG/simplpedpop aux", simpl_seed) as aux_rand.
- simplpedpop_coordinator_step / assemble_sum_coms: echo per-dealer
constant-term commitments, sum non-constant-term commitments,
collect PoPs (not verified by the coordinator, as in the reference).
- simplpedpop_participant_step2: own-commitment echo check, per-dealer
infinity rejection and PoP verification against the x-only
coms_to_secrets[i], TapTweak applied before share verification
(secshare vs pubshare check on tweaked values), eq_input =
u32be(t) || sum_coms committing to the UNTWEAKED summed commitment.
encpedpop.h / encpedpop_impl.h (mirrors encpedpop.py):
- simpl_seed / aux / secnonce derivations from (hostseckey, random,
enc_context) via "BIP DKG/encpedpop seed", "BIP DKG/simplpedpop aux"
and "BIP DKG/encpedpop secnonce"; pubnonce = pubkey_gen_plain(secnonce).
- encaps_multi / encrypt_multi: per-recipient pad context
u32be(i) || enc_context, self-pad at the own index (no ECDH),
libsecp256k1-style ECDH pad otherwise with sender-first ordering;
encryption is additive mod n so the coordinator can sum encrypted
shares per recipient.
- decaps_multi / decrypt_sum: receiver-side pads, invalid or infinity
pubnonce maps to FAULTY_PARTICIPANT_OR_COORDINATOR(sender).
- coordinator_step: checked scalar parse of encrypted shares
(overflow blames the sender), per-recipient summation.
- participant_step2: pubnonce echo check (mismatch ->
FAULTY_COORDINATOR), decrypt, delegate to simplpedpop step2,
eq_input extended with enckeys || pubnonces.
util.h: add SECP256K1_CHILLDKG_MAX_PARTICIPANTS (128, matching frost)
and the internal fault enum mirroring the reference's exception
taxonomy (FAULTY_COORDINATOR, FAULTY_PARTICIPANT,
FAULTY_PARTICIPANT_OR_COORDINATOR,
UNKNOWN_FAULTY_PARTICIPANT_OR_COORDINATOR, INVALID_INPUT). The public
blame-reporting enum arrives with the Phase 3 API.
State structs are fixed-size (no malloc, cap 128 participants). All
secret temporaries are cleared; negligible-probability secret-
dependent failures are declassified before branching.
Documented deviations where the reference crashes with non-protocol
errors: infinity sum_coms[0] in invalid_taproot_commit (unreachable
after PoP verification) and tweak-hash overflow (negligible) return
UNKNOWN_FAULTY_PARTICIPANT_OR_COORDINATOR; a wrong cmsg length maps
to FAULTY_COORDINATOR. Investigation procedures are deferred to
Phase 5 per the plan.
tests_impl.h: byte-exact n=3/t=2 happy-path vectors for both layers
generated from the Python reference (pmsg/cmsg/eq_input/enc_secshares
and all DKG outputs), plus PoP reject cases (tampered, wrong index,
infinity commitment, wrong echo, tampered non-constant-term sum),
coordinator blame (bad commitment, overflowing encrypted share),
encaps/decaps pad symmetry for all sender/receiver pairs including
self-pad, encrypt->sum->decrypt_sum roundtrip, tampered encrypted
share, invalid pubnonce blame, and input-validation rejects.
Verified: make check 3/3 suites pass (incl. noverify_tests running the
module); CMake ctest 361/361; ./tests --target=chilldkg runs all 9
module tests green.
1605b02f cd49c57e 453949ab 57315a69 97de5120 c5da3bde 99ab4a10 d071aa56 1d146ac3 322d0a43 c7a7f732 ac561601 dfe042fe 3019186a 95e68158 10f546a2 c0a2aba0 ' into temp-merge-1811
c8206b1c b6c2a3cd e7f7083b be5e4f02 5c751833 540fec8a aa2a39c1 8d445730 f9a944ff 2d9137ce 4721e077 471e3a13 ebb35882 1a53f496 c7a52400 ' into temp-merge-1809
c8206b1c b6c2a3cd e7f7083b be5e4f02 5c751833 540fec8a aa2a39c1 8d445730 f9a944ff 2d9137ce 4721e077 471e3a13 ebb35882 1a53f496 c7a52400 ' into temp-merge-1809
libsecp256k1-zkp
A fork of libsecp256k1 with support for advanced and experimental features
Added features:
- Experimental module for ECDSA adaptor signatures.
- Experimental module for ECDSA sign-to-contract.
- Experimental modules for Confidential Assets (Pedersen commitments, range proofs, and surjection proofs).
- Experimental module for address whitelisting.
- Experimental module for Schnorr signature half-aggregation.
- Experimental module for FROST (BIP 445).
Experimental features are made available for testing and review by the community. The APIs of these features should not be considered stable.
Build steps
Obtaining and verifying
The git tag for each release (e.g. v0.6.0) is GPG-signed by one of the maintainers.
For a fully verified build of this project, it is recommended to obtain this repository
via git, obtain the GPG keys of the signing maintainer(s), and then verify the release
tag's signature using git.
This can be done with the following steps:
- Obtain the GPG keys listed in SECURITY.md.
- If possible, cross-reference these key IDs with another source controlled by its owner (e.g. social media, personal website). This is to mitigate the unlikely case that incorrect content is being presented by this repository.
- Clone the repository:
git clone https://github.com/bitcoin-core/secp256k1 - Check out the latest release tag, e.g.
git checkout v0.7.1 - Use git to verify the GPG signature:
% git tag -v v0.7.1 | grep -C 3 'Good signature' gpg: Signature made Mon 26 Jan 2026 07:42:46 PM UTC gpg: using RSA key 2840EAABF4BC9F0FFD716AFAFBAFCC46DE2D3FE2 gpg: Good signature from "Pieter Wuille <pieter@wuille.net>" [unknown] gpg: aka "Pieter Wuille <pieter.wuille@gmail.com>" [full] gpg: aka "[jpeg image of size 5996]" [undefined] gpg: WARNING: This key is not certified with a trusted signature! gpg: There is no indication that the signature belongs to the owner. Primary key fingerprint: 133E AC17 9436 F14A 5CF1 B794 860F EB80 4E66 9320 Subkey fingerprint: 2840 EAAB F4BC 9F0F FD71 6AFA FBAF CC46 DE2D 3FE2
Building with Autotools
$ ./autogen.sh # Generate a ./configure script
$ ./configure # Generate a build system
$ make # Run the actual build process
$ make check # Run the test suite
$ sudo make install # Install the library into the system (optional)
To compile optional modules (such as Schnorr signatures), you need to run ./configure with additional flags (such as --enable-module-schnorrsig). Run ./configure --help to see the full list of available flags. For experimental modules, you will also need --enable-experimental as well as a flag for each individual module, e.g. --enable-module-rangeproof.
Building with CMake
To maintain a pristine source tree, CMake encourages to perform an out-of-source build by using a separate dedicated build tree.
Building on POSIX systems
$ cmake -B build # Generate a build system in subdirectory "build"
$ cmake --build build # Run the actual build process
$ ctest --test-dir build # Run the test suite
$ sudo cmake --install build # Install the library into the system (optional)
To compile optional modules (such as Schnorr signatures), you need to run cmake with additional flags (such as -DSECP256K1_ENABLE_MODULE_SCHNORRSIG=ON). Run cmake -B build -LH or ccmake -B build to see the full list of available flags.
Cross compiling
To alleviate issues with cross compiling, preconfigured toolchain files are available in the cmake directory.
For example, to cross compile for Windows:
$ cmake -B build -DCMAKE_TOOLCHAIN_FILE=cmake/x86_64-w64-mingw32.toolchain.cmake
To cross compile for Android with NDK (using NDK's toolchain file, and assuming the ANDROID_NDK_ROOT environment variable has been set):
$ cmake -B build -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK_ROOT}/build/cmake/android.toolchain.cmake" -DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=28
Building on Windows
The following example assumes Visual Studio 2022. Using clang-cl is recommended.
In "Developer Command Prompt for VS 2022":
>cmake -B build -T ClangCL
>cmake --build build --config RelWithDebInfo
Usage examples
Usage examples can be found in the examples directory. To compile them you need to configure with --enable-examples.
- ECDSA example
- Schnorr signatures example
- Deriving a shared secret (ECDH) example
- ElligatorSwift key exchange example
- MuSig2 Schnorr multi-signatures example
To compile the examples, make sure the corresponding modules are enabled.
Benchmark
If configured with --enable-benchmark (which is the default), binaries for benchmarking the libsecp256k1-zkp functions will be present in the root directory after the build.
To print the benchmark result to the command line:
$ ./bench_name
To create a CSV file for the benchmark result :
$ ./bench_name | sed '2d;s/ \{1,\}//g' > bench_name.csv
Reporting a vulnerability
See SECURITY.md
Contributing to libsecp256k1
See CONTRIBUTING.md