mirror of
https://github.com/saymrwulf/swisspost-evoting-go-poc.git
synced 2026-07-24 19:43:51 +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>
43 lines
1.3 KiB
Go
43 lines
1.3 KiB
Go
package protocol
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import (
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"fmt"
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"math/big"
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emath "github.com/user/evote/pkg/math"
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)
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func bigIntN(n int) *big.Int { return big.NewInt(int64(n)) }
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// RunDemoElection runs a complete election ceremony with the given parameters.
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func RunDemoElection(numVoters, numOptions int) {
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fmt.Println("========================================")
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fmt.Println(" Swiss Post E-Voting Protocol PoC (Go)")
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fmt.Println("========================================")
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fmt.Printf(" Voters: %d, Options: %d, CCs: 4\n", numVoters, numOptions)
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fmt.Println()
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// Phase 1: Setup
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fmt.Println("--- SETUP PHASE ---")
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cfg := DefaultConfig(numVoters, numOptions)
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fmt.Printf(" Group: %d-bit safe prime\n", cfg.Group.Q().BitLen())
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event := Setup(cfg)
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fmt.Printf(" Generated %d voting cards\n", numVoters)
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fmt.Printf(" Mapping table: %d entries\n", event.MappingTable.Size())
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fmt.Println(" Setup complete.")
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// Phase 2: Voting
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fmt.Println("\n--- VOTING PHASE ---")
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for v := 0; v < numVoters; v++ {
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// Randomly select 1 option for each voter (CSPRNG; simulation only).
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selected := []int{int(emath.RandomBigInt(bigIntN(numOptions)).Int64())}
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CastVote(event, v, selected)
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}
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fmt.Printf(" All %d votes cast.\n", numVoters)
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// Phase 3: Tally
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Tally(event)
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// Phase 4: Verify
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VerifyTally(event)
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}
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