mirror of
https://github.com/saymrwulf/swisspost-evoting-go-poc.git
synced 2026-05-14 20:58:03 +00:00
saymrwulf
e8b6f30871
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.
133 lines
3.3 KiB
Go
133 lines
3.3 KiB
Go
package mixnet
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import (
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"crypto/rand"
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"math/big"
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"testing"
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"github.com/user/evote/pkg/elgamal"
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emath "github.com/user/evote/pkg/math"
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)
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func TestMultiExponentiationArgument(t *testing.T) {
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q := testSafePrimeQ(256)
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p := new(big.Int).Mul(big.NewInt(2), q)
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p.Add(p, big.NewInt(1))
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g := big.NewInt(4)
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group, err := emath.NewGqGroup(p, q, g)
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if err != nil {
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t.Fatal(err)
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}
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zqGroup := emath.ZqGroupFromGqGroup(group)
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l := 2
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pk := elgamal.GenKeyPair(group, l).PK
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n := 3
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m := 1
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ck := GenCommitmentKey(n, group)
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cMatrix := make([]*elgamal.CiphertextVector, m)
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for i := 0; i < m; i++ {
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cts := make([]elgamal.Ciphertext, n)
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for j := 0; j < n; j++ {
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r := emath.RandomZqElement(zqGroup)
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cts[j] = elgamal.EncryptOnes(r, pk)
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}
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cMatrix[i] = elgamal.NewCiphertextVector(cts)
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}
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aCols := make([]*emath.ZqVector, m)
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for j := 0; j < m; j++ {
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aCols[j] = emath.RandomZqVector(n, zqGroup)
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}
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A := emath.ZqMatrixFromColumns(aCols)
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r := emath.RandomZqVector(m, zqGroup)
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cA := ck.CommitMatrix(A, r)
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// Target = Enc(1; rho) * Π multiExp(cMatrix[i], A[:,i])
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rhoVal := emath.RandomZqElement(zqGroup)
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cTarget := identityCiphertext(l, group)
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for i := 0; i < m; i++ {
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ct := multiExpCiphertextRow(cMatrix[i], A.GetColumn(i))
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cTarget = cTarget.Multiply(ct)
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}
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encRho := elgamal.EncryptOnes(rhoVal, pk)
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cTarget = cTarget.Multiply(encRho)
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arg := GenMultiExponentiationArgument(cMatrix, cTarget, cA, A, r, rhoVal, pk, ck, group)
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ok := VerifyMultiExponentiationArgument(arg, cMatrix, cTarget, cA, pk, ck, group)
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if !ok {
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t.Fatal("MultiExponentiationArgument verification failed")
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}
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t.Log("MultiExponentiationArgument verification PASSED!")
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}
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func TestMultiExpLargerMatrix(t *testing.T) {
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q := testSafePrimeQ(256)
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p := new(big.Int).Mul(big.NewInt(2), q)
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p.Add(p, big.NewInt(1))
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g := big.NewInt(4)
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group, err := emath.NewGqGroup(p, q, g)
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if err != nil {
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t.Fatal(err)
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}
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zqGroup := emath.ZqGroupFromGqGroup(group)
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l := 2
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pk := elgamal.GenKeyPair(group, l).PK
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n := 2
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m := 2
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ck := GenCommitmentKey(n, group)
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cMatrix := make([]*elgamal.CiphertextVector, m)
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for i := 0; i < m; i++ {
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cts := make([]elgamal.Ciphertext, n)
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for j := 0; j < n; j++ {
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r := emath.RandomZqElement(zqGroup)
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cts[j] = elgamal.EncryptOnes(r, pk)
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}
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cMatrix[i] = elgamal.NewCiphertextVector(cts)
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}
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aCols := make([]*emath.ZqVector, m)
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for j := 0; j < m; j++ {
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aCols[j] = emath.RandomZqVector(n, zqGroup)
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}
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A := emath.ZqMatrixFromColumns(aCols)
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r := emath.RandomZqVector(m, zqGroup)
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cA := ck.CommitMatrix(A, r)
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rhoVal := emath.RandomZqElement(zqGroup)
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cTarget := identityCiphertext(l, group)
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for i := 0; i < m; i++ {
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ct := multiExpCiphertextRow(cMatrix[i], A.GetColumn(i))
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cTarget = cTarget.Multiply(ct)
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}
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encRho := elgamal.EncryptOnes(rhoVal, pk)
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cTarget = cTarget.Multiply(encRho)
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arg := GenMultiExponentiationArgument(cMatrix, cTarget, cA, A, r, rhoVal, pk, ck, group)
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ok := VerifyMultiExponentiationArgument(arg, cMatrix, cTarget, cA, pk, ck, group)
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if !ok {
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t.Fatal("MultiExponentiationArgument (2x2) verification failed")
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}
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t.Log("MultiExponentiationArgument (2x2) verification PASSED!")
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}
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func testSafePrimeQ(bits int) *big.Int {
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for {
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q, err := rand.Prime(rand.Reader, bits)
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if err != nil {
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panic(err)
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}
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p := new(big.Int).Mul(big.NewInt(2), q)
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p.Add(p, big.NewInt(1))
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if p.ProbablyPrime(64) {
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return q
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}
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}
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}
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