Take the live-math cockpit down to the level of the Swiss Post crypto-primitives
class structure. The shuffle proof is no longer one line — you can now watch it
being constructed:
- Pedersen matrix commitment (CommitmentService analog): c_A = Comm(A; r),
c_{A,j} = h^{r_j} Π g_i^{A_ij}, emitted from CommitMatrix.
- All five Bayer-Groth sub-arguments, mirroring the *ArgumentService classes:
ShuffleArgument (composition + x,y,z challenges), ProductArgument,
HadamardArgument (entrywise product), ZeroArgument (bilinear star-map),
SingleValueProductArgument, MultiExponentiationArgument — each emits its
defining relation as LaTeX with live dimensions.
- Partial decryption + decryption proof (DecryptionProofService analog):
φ'_i = φ_i·γ_i^{-sk} with the ZK proof that log_g(pk) = log_γ(γ^sk).
New trace.KindArgument. Low-level Commit stays uninstrumented (called in
verification too — would flood the stream); CommitMatrix is the semantic step.
Test: a 6-voter ceremony (N=6 → 2×3 shuffle matrix, so m>1 and the full argument
tree runs) captures 345 live events across 8 kinds, and asserts all five named
sub-arguments appear.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Correctness/security review of the whole PoC, with fixes and regression tests.
Cryptographic soundness:
- mixnet: enforce the multi-exponentiation c_{B_m}=commit(0;0) check that was
stubbed out with an empty if — without it a malicious mixer can prove a
non-permutation shuffle.
- zkp: derive all four Fiat-Shamir challenges via RecursiveHashToZq instead of
a biased `hash mod q` (which also capped the challenge space at 256 bits for
production-sized groups).
Verification honesty:
- protocol: VerifyTally now actually calls zkp.VerifySchnorrProof and returns
the true aggregate result instead of an unconditional true.
- protocol: persist the padded mix input (event.MixInput) so the verifier checks
shuffle 0 against the same padding the tally used (fixes false INVALID for N<2).
Other correctness:
- kdf: length-prefix BuildKDFInfo parts so the info encoding is injective.
- math: GqElementFromSquareRoot accepts the valid root q (off-by-one that could
panic in HashAndSquare); RandomGqElement samples the full canonical range.
- cmd: validate demo --voters/--options instead of panicking on degenerate values.
- protocol: use crypto/rand in the demo driver (drop the last math/rand import).
Transport security (new): pkg/transportsec exposes Ed25519 signatures and X25519
ECDH — implemented in Rust (rust/transportsec: ed25519-dalek, x25519-dalek),
linked into Go via cgo. No RSA. Cross-language conformance test proves the Rust
Ed25519 signatures interoperate with Go's crypto/ed25519. Makefile builds the
Rust static lib before the Go binary.
Tests: added unit/round-trip/tamper coverage for math, hash, elgamal, zkp,
mixnet, kdf, returncodes, protocol (end-to-end), and the Rust FFI bridge.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Proof-of-concept reimplementation of the Swiss Post e-voting
cryptographic protocol in Go. Single binary, 52 source files,
2 dependencies. Covers ElGamal encryption, Bayer-Groth verifiable
shuffles, zero-knowledge proofs, return codes, and a full
election ceremony demo.
