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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.
39 lines
1.2 KiB
Go
39 lines
1.2 KiB
Go
package returncodes
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import (
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"encoding/hex"
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"math/big"
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"github.com/user/evote/pkg/hash"
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emath "github.com/user/evote/pkg/math"
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)
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// GenerateShortCode generates a short human-readable return code from a GqElement.
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func GenerateShortCode(value emath.GqElement) string {
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hashBytes := hash.RecursiveHash(hash.HashableBigInt{Value: value.Value()})
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// Take first 4 bytes and encode as hex for a short code
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return hex.EncodeToString(hashBytes[:4])
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}
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// ComputeLCCValue computes the long choice return code value from partial choice return codes.
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// lCC = H(pC, vcID, eeID, tau)
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func ComputeLCCValue(pC emath.GqElement, vcID, eeID string, tau *big.Int) *big.Int {
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return hash.RecursiveHashToZq(
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pC.Group().Q(),
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hash.HashableBigInt{Value: pC.Value()},
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hash.HashableString{Value: vcID},
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hash.HashableString{Value: eeID},
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hash.HashableBigInt{Value: tau},
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)
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}
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// ComputeLVCCValue computes the long vote cast return code value.
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// lVCC = H(pVCC, vcID, eeID)
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func ComputeLVCCValue(pVCC emath.GqElement, vcID, eeID string) *big.Int {
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return hash.RecursiveHashToZq(
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pVCC.Group().Q(),
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hash.HashableBigInt{Value: pVCC.Value()},
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hash.HashableString{Value: vcID},
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hash.HashableString{Value: eeID},
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)
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}
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