mirror of
https://github.com/saymrwulf/swisspost-evoting-go-poc.git
synced 2026-09-05 20:30:43 +00:00
saymrwulf
127ae61d11
The return code the voter checks is now genuinely computed by the CCs from the submitted ciphertext, not looked up from the card: - returncode_extract.go: after a ballot is accepted, the server asks each CC to exponentiate E2 by its return-code key (product over CCs = Enc(vote^Σk)), then each CC contributes a partial-decryption factor; the server recovers vote^Σk, which equals the card base prime_sel^Σk, and looks up the short code. - The server returns that code to the voter, who checks it against the card for the chosen option; a mismatch aborts with a clear error. Soundness test: a malicious client that encrypts option A for the tally (E1) but option B in the return-code channel (E2) is REJECTED by the plaintext-equality proof — so the code shown always reflects the tallied vote. This closes the cast-as-intended gap (the old return codes were decorative, finding F16). Card lCC now uses a fixed tau so extraction can recompute it without learning the option up front. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
59 lines
1.7 KiB
Go
59 lines
1.7 KiB
Go
package party
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import (
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"fmt"
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"github.com/user/evote/pkg/transport"
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)
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// Phase message handlers. These are filled in incrementally (setup, then
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// voting, then tally). Until a phase is implemented its handler rejects unknown
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// message types cleanly rather than panicking — the transport boundary must
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// never crash on an unexpected message.
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func (p *SetupComponent) handleSetupMsg(env *transport.Envelope) (*transport.Envelope, error) {
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return nil, fmt.Errorf("%s: unhandled message type %q", p.id.Name, env.Type)
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}
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func (p *ControlComponent) handleCCMsg(env *transport.Envelope) (*transport.Envelope, error) {
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switch env.Type {
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case MsgGenCCKeys:
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return p.handleGenCCKeys(env)
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case MsgLongCodeShareReq:
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return p.handleLongCodeShare(env)
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case MsgVerifyBallot:
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return p.handleVerifyBallot(env)
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case MsgShuffle:
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return p.handleShuffle(env)
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case MsgRCExpReq:
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return p.handleRCExp(env)
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case MsgRCDecReq:
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return p.handleRCDec(env)
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default:
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return nil, fmt.Errorf("%s: unhandled message type %q", p.id.Name, env.Type)
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}
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}
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func (p *ElectoralBoard) handleEBMsg(env *transport.Envelope) (*transport.Envelope, error) {
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switch env.Type {
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case MsgGenEBKey:
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return p.handleGenEBKey(env)
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case MsgFinalMix:
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return p.handleFinalMix(env)
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default:
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return nil, fmt.Errorf("%s: unhandled message type %q", p.id.Name, env.Type)
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}
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}
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func (p *VotingServer) handleServerMsg(env *transport.Envelope) (*transport.Envelope, error) {
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switch env.Type {
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case MsgMappingTable:
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return p.handleMappingTable(env)
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case MsgCastBallot:
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return p.handleCastBallot(env)
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case MsgStartTally:
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return p.handleStartTally(env)
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default:
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return nil, fmt.Errorf("%s: unhandled message type %q", p.id.Name, env.Type)
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}
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}
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