mirror of
https://github.com/saymrwulf/swisspost-evoting-go-poc.git
synced 2026-07-23 19:32:29 +00:00
saymrwulf
ec4be74e17
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>
46 lines
1 KiB
Go
46 lines
1 KiB
Go
package returncodes
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import (
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"math/big"
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"reflect"
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"sort"
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"testing"
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emath "github.com/user/evote/pkg/math"
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)
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func TestEncodeDecodeRoundTrip(t *testing.T) {
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primes := emath.SmallPrimes(5)
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cases := [][]int{
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{},
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{0},
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{4},
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{0, 2, 4},
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{1, 3},
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}
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for _, sel := range cases {
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product := EncodeVote(sel, primes)
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got := DecodeVote(product, primes)
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sort.Ints(got)
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want := append([]int(nil), sel...)
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sort.Ints(want)
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if len(want) == 0 && len(got) == 0 {
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continue
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}
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if !reflect.DeepEqual(got, want) {
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t.Fatalf("round-trip mismatch: selected %v, decoded %v", want, got)
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}
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}
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}
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// TestDecodeVoteRepeatedPrime confirms a squared prime decodes to the option
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// selected twice (the encoding is multiplicative, so multiplicity matters).
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func TestDecodeVoteRepeatedPrime(t *testing.T) {
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primes := emath.SmallPrimes(3)
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product := new(big.Int).Mul(primes[1], primes[1])
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got := DecodeVote(product, primes)
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if len(got) != 2 || got[0] != 1 || got[1] != 1 {
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t.Fatalf("expected [1 1], got %v", got)
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}
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}
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