mirror of
https://github.com/saymrwulf/swisspost-evoting-go-poc.git
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saymrwulf
a443e44875
Voters encrypt their selection under the election key, build the (sound) exponentiation proof binding the ballot to their verification-card key, and submit to the voting server. The server validates every group element on receipt, routes the ballot to all four CCs for proof verification, and stores it only on unanimous acceptance — persisting vcPK (finding F6) so the proof statement is reconstructible by any party. - voting.go: castBallot (voter), handleCastBallot (server), handleVerifyBallot (CC). The CC re-derives the proof statement and verifies it; a malformed proof or bad group element yields a clean reject, never a panic (the trust-boundary hardening deferred from the due-diligence pass). - wire.go: exponentiation-proof DTO. Tests: 4 ballots flow end-to-end and are stored with vcPK; a ballot with a zeroed proof is rejected by the CCs and never stored. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
package party
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import (
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"math/big"
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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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"github.com/user/evote/pkg/mixnet"
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"github.com/user/evote/pkg/returncodes"
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"github.com/user/evote/pkg/zkp"
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)
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// The state structs below hold each party's PRIVATE state. Nothing here may be
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// read by another party except through an explicit signed message.
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// setupState is the setup component's working store while assembling cards.
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type setupState struct {
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primes []*big.Int
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votingCards []*votingCard
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mappingTable *returncodes.MappingTable
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electionPK elgamal.PublicKey
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returnCodePK elgamal.PublicKey
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}
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// ccState is a control component's private key material and mix state.
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type ccState struct {
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keyPair elgamal.KeyPair
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returnCodeSecret emath.ZqElement
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schnorrProofs []zkp.SchnorrProof
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// Tally working state.
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shuffle mixnet.VerifiableShuffle
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decProofs []zkp.DecryptionProof
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shuffleIn *elgamal.CiphertextVector
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shuffleOut *elgamal.CiphertextVector
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}
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// ebState is the electoral board's private key material.
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type ebState struct {
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passwords []string
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keyPair elgamal.KeyPair
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}
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// serverState is the voting server / ballot box.
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type serverState struct {
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mappingTable *returncodes.MappingTable
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ballotBox []encryptedBallot
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electionPK elgamal.PublicKey
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returnCodePK elgamal.PublicKey
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primes []*big.Int
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}
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// voterState is a voter client's private card and ballot secrets.
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type voterState struct {
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card *votingCard
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electionPK elgamal.PublicKey
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primes []*big.Int
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vcSK emath.ZqElement
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selected []int
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}
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// votingCard is a voter's credential bundle (private to the voter, produced by
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// the setup component and delivered over a confidential channel).
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type votingCard struct {
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VoterID string `json:"voter_id"`
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VerificationCardID string `json:"vc_id"`
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StartVotingKey string `json:"svk"`
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ChoiceReturnCodes []string `json:"choice_return_codes"`
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VoteConfirmCode string `json:"vote_confirm_code"`
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BallotCastingKey string `json:"bck"`
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}
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// encryptedBallot is a ballot as stored in the ballot box.
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type encryptedBallot struct {
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VoterID string
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VerificationCardID string
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Ciphertext elgamal.Ciphertext
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VcPK emath.GqElement
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}
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