Vote Data

Vote Envelope

The Vote Envelope contains a (possibly encrypted) Vote Package and provides details to prove that the incoming vote is valid. Some fields may be optional depending on the election mode and envelopeType.

When envelopeType.ANONYMOUS is enabled

This section will be available soon.

When envelopeType.ANONYMOUS is disabled

A signed (non-anonymous) Vote Envelope features the election ID, the Census Merkle Proof of the user, a nonce to prevent replay attacks, the index of the encryption keys used, a Base64 representation of the Vote Package and the user's signature.

In order to guarantee 100% reproduceability of the signature, the Vote Envelope is encoded as a Protobuf model and serialized into a byte array. This byte array is then signed and both fields are sent via a SignedTx model to a Gateway.

// Protobuf models

message VoteEnvelope {
        bytes nonce = 1;  // Unique number per vote attempt, so that replay attacks can't reuse this payload
        bytes electionId = 2;  // The election for which the vote is cast
        Proof proof = 3;  // One of ProofGraviton, ProofIden3, ProofEthereumStorage, ProofEthereumAccount, or ProofCA
        bytes votePackage = 4;   // JSON string of the Vote Package, encoded as bytes. It may be encrypted.
        bytes nullifier = 5;  // Hash of the private key + electionId (optional, depending on the type)

        repeated uint32 encryptionKeyIndexes = 6; // On encrypted votes, contains the (sorted) indexes of the keys used to encrypt
}

// ...

message Tx {
    oneof payload {
        VoteEnvelope vote = 1;
        // ...
    }
}

message SignedTx {
    bytes tx = 1; // The bytes produced by Marshaling a Tx{} message
    optional bytes signature = 2; // The signature for the tx bytes. 
    // signature is only required in those transactions that actually need a signature.
        // I.e zk-SNARKs based transactions won't needed, however the transaction should use
        // this message type in order to preserve consistency on the Vochain
}

Vote Package

Contains the actual votes and is part of the Vote Envelope.

{
    "nonce": "01234567890abcdef", // 8+ byte random string to prevent guessing the encrypted payload before the reveal key is released
    "votes": [  // Directly mapped to the `questions` field of the metadata
        1, 3, 2
    ]
}

When envelopeType.ENCRYPTED_VOTE is disabled

• The nonce can be omitted.
• The package has to be serialized as a JSON string and encoded as bytes.

When envelopeType.ENCRYPTED_VOTE is enabled

• The nonce is mandatory.
• The package has to be serialized as a JSON string encoded as bytes.
• It must be encrypted with a subset of the public keys or all of them.
• The index of the public keys used to encrypt must be included in the Vote Envelope in the exact order they have been used.

Results

Requests to the Results API will return an Array of number arrays, following the Ballot Protocol. They will contain a bi-dimensional array of integers, aggregating the values currently stored on the Vochain.

The interpretation of these values is left to the Client apps, and is determined by the results.aggregation and results.display fields of the Election Metadata, listed above.