Kgothatso Ngako e462f7c1ac chilldkg: Phase 1 - internal primitives (util, vss)
Add the byte-exact internal primitives for the ChillDKG module,
mirroring the Python reference implementation of the bip-frost-dkg
draft (v0.3.0-dev), pinned to upstream commit
a91896883f85b159415ecf298d5e844879af112d.

util.h / util_impl.h (mirrors chilldkg_ref/util.py):
- Point (de)serialization with explicit point-at-infinity support:
  33 zero bytes <-> infinity, otherwise SEC compressed. Checked parse
  rejects invalid encodings and out-of-range x coordinates
  (point_save/point_load, xonly_save/xonly_load).
- Internal parameterized-tag BIP-340 Schnorr sign/verify
  (chilldkg_schnorrsig_sign/_verify): tag prefix selects the
  <prefix>/aux, /nonce, /challenge subtags ("BIP DKG/pop message" for
  proofs of possession, "BIP0340" for CertEq signatures and recovery
  acks), arbitrary-length messages, pad33 zero-padding helper. The
  public schnorrsig API hardcodes BIP0340/32-byte messages, so the
  algorithm is replicated from secp256k1_schnorrsig_sign_internal with
  a custom tag; cross-checked against secp256k1_schnorrsig_sign32.
- Tagged hashes via secp256k1_sha256_initialize_tagged:
  "BIP DKG/params_hash", "BIP DKG/encpedpop seed",
  "BIP DKG/simplpedpop aux", "BIP DKG/encpedpop secnonce",
  "BIP DKG/encpedpop ecdh", "BIP DKG/encaps_multi self_pad",
  "BIP DKG/vss coeffs", and BIP-341 "TapTweak" (32-byte x-only input).
- params_hash = TH("BIP DKG/params_hash", u32be(t) || hostpubkeys)
  (note: plan had the operand order reversed; the reference hashes t
  first).
- ECDH pads: reuses the ecdh module's SHA256-of-compressed-shared-
  point hash, then TH("BIP DKG/encpedpop ecdh", ecdh ||
  sender_pubnonce || receiver_hostpubkey || context) with a sending
  flag fixing the sender|receiver order; self_pad for the own index.
  Pads are parsed wrapping (mod-n reduction); wire scalars, VSS
  coefficients and the TapTweak are parsed checked.

vss.h / vss_impl.h (mirrors chilldkg_ref/vss.py):
- vss_gen_coeffs: per-coefficient TH("BIP DKG/vss coeffs", seed ||
  u32be(j)), checked parse with bitwise error accumulation.
- vss_poly_eval (Horner) and vss_secshare_for with the x = id+1
  convention (safe at UINT32_MAX).
- vss_commit (constant-time ecmult_gen, zero coefficient -> infinity),
  vss_pubshare (powers-of-x over commitments, skips infinity),
  vss_commitment_add, vss_verify_secshare.
- vss_invalid_taproot_commit: TapTweak applied to the x-only constant
  term so the Taproot script path is unspendable; returns tweak and
  pubtweak.

tests_impl.h: 7 vector tests (tagged hashes, params_hash, point
serialization incl. infinity roundtrip and parity prefixes, checked
vs wrapping scalar parse at the group order boundary, custom-tag
schnorrsig incl. wrong-tag/key/msg rejection, ECDH pad sender/receiver
symmetry, VSS coeff derivation/Horner/commitment/pubshare/tweak) with
expected values generated once from the Python reference
(committed into the test file, reference commit recorded).

Verified: make check 3/3 suites pass; CMake ctest all pass;
./tests --target=chilldkg runs all 7 new tests green in both verify
and noverify builds.
2026-08-31 04:05:15 +02:00
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2013-05-09 15:24:32 +02:00
2026-08-31 00:05:16 +02:00

libsecp256k1-zkp

Dependencies: None

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:

  1. Obtain the GPG keys listed in SECURITY.md.
  2. 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.
  3. Clone the repository:
    git clone https://github.com/bitcoin-core/secp256k1
    
  4. Check out the latest release tag, e.g.
    git checkout v0.7.1
    
  5. 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.

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

Description
Experimental fork of libsecp256k1 with support for pedersen commitments and range proofs.
Readme 15 MiB
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