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https://github.com/saymrwulf/swisspost-evoting-go-poc.git
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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.
53 lines
1.3 KiB
Go
53 lines
1.3 KiB
Go
package mixnet
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import (
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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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// VerifiableShuffle holds the result of a verifiable shuffle.
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type VerifiableShuffle struct {
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ShuffledCiphertexts *elgamal.CiphertextVector
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Argument ShuffleArgument
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}
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// GenVerifiableShuffle performs a shuffle and generates a proof.
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func GenVerifiableShuffle(
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C *elgamal.CiphertextVector,
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pk elgamal.PublicKey,
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group *emath.GqGroup,
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) VerifiableShuffle {
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// Determine matrix dimensions
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N := C.Size()
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_, n := GetMatrixDimensions(N)
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// Generate commitment key of size n
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ck := GenCommitmentKey(n, group)
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// Perform shuffle
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shuffle := GenShuffle(C, pk)
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// Generate shuffle argument
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arg := GenShuffleArgument(C, shuffle.Shuffled, shuffle.Perm, shuffle.Rho, pk, ck, group)
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return VerifiableShuffle{
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ShuffledCiphertexts: shuffle.Shuffled,
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Argument: arg,
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}
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}
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// VerifyShuffle verifies a verifiable shuffle.
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func VerifyShuffle(
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C *elgamal.CiphertextVector,
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vs VerifiableShuffle,
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pk elgamal.PublicKey,
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group *emath.GqGroup,
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) bool {
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N := C.Size()
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_, n := GetMatrixDimensions(N)
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// Regenerate commitment key (deterministic from group)
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ck := GenCommitmentKey(n, group)
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return VerifyShuffleArgument(vs.Argument, C, vs.ShuffledCiphertexts, pk, ck, group)
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}
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