Auto-Reveal via Shutter Network

[jaybuidl]

High Level Specs

Initialization

sequenceDiagram
    participant Shutter Key Broadcast Contract
    participant Shutter Keypers

    Shutter Keypers->>Shutter Keypers: Keyper Set becomes active
    Shutter Keypers->>Shutter Keypers: Generate new Eon key
    Shutter Keypers->>Shutter Key Broadcast Contract: Broadcast Eon public key

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During a dispute

sequenceDiagram
    %% Participants
    participant Voter as Juror
    participant Bot as Reveal Bot<br>(anyone)
    participant ShutterSDK as Shutter SDK
    participant Shutter as Shutter Network
    participant Contract as ShutterDisputeKit

    %% --- Vote Commitment Phase ---
    Note over Voter,Contract: Voting session opens
    Voter->>Shutter: register_identity(decryptionTimestamp)
    Shutter-->>Voter: {identity, eon_key}
    Voter->>Voter: generate random salt
    Voter->>ShutterSDK: encrypt(message: {choice, justification, salt}, identity, eon_key)
    ShutterSDK-->>Voter: {encryptedVote}
    Voter->>Voter: commitHash = keccak256(choice, justification, salt)
    Voter->>Contract: castCommit(voteIDs, commitHash, identity, encryptedVote)
    Contract-->>Contract: emits CommitCast(voter, voteIDs, commitHash, identity, encryptedVote)

    %% --- Vote Reveal Phase (after delay) ---
    Note over Voter,Contract: Voting session ends, Shutter Network releases decryption key
    Bot->>Contract: query CommitCast event({voter})
    Contract-->>Bot: CommitCast event(voter, voteIDs, commitHash, identity, encryptedVote)
    Bot->>ShutterSDK: decrypt(encryptedVote, identity)
    ShutterSDK->>Shutter: get_decryption_key(identity)
    Shutter-->>ShutterSDK: decryption_key
    ShutterSDK-->>Bot: {choice, justification, salt}
    Bot->>Contract: castVote(voteIDs, choice, salt, justification)
    Contract-->>Contract: verify vote hash against commitHash
    Contract-->>Contract: emits VoteCast(voteIDs, voter, choice, justification, salt)

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The disputeID and roundID are omitted for clarity.

Considerations

• Allow the encrypted vote and justification to be submitted along with the committment and emit the enrypted value as an Event so it can be picked up by the Keypers
• Add a function batchCastVote that is callable by anyone (i.e. no check against msg.sender) and thereby allows third parties to submit decrypted vote batches on behalf of the users.
• There could be a fee incentive for the third party to offset the transaction costs (deposited by jurors in castCommit, excess can be refunded).
• Possible solution for the not commited to justification:
  Jurors EC-Recoverable sign the justification which allows verifivation of the sender.

Reference

Shutter JS library
Shutter JS example use by Snapshot
Default commit/reveal implementation

[jaybuidl]

March 2025 update: Shutter API launch

Shutter API: Threshold Encryption Service
Shutter API Documentation for dApp Developers.
Quick Start Guide to Shutter API.