Reputation

Definition of reputation in UniRep

Reputation

• The reputation in UniRep protocol includes

  • posRep: is the positive reputation given by the attester

  • negRep: is the negative reputation given by the attester

  • graffiti: is the message given by the attester

  • signUp: indicates if the attester authenticates the user

• The hash of the reputation is computed by the Poseidon hash function.

const hashReputation = hash(posRep, negRep, graffiti, signUp)

• The overall reputation status of a user is stored in the user's User State Tree

  • where the index of the leaf is the attester ID

  • the leaf value is the accumulated hashReputation that the attester gives

Attestation

• The attestation is almost the same as reputation, but it includes an attesterId

• The hash of attestation is computed by

const hashAttestation = hash(attesterId, posRep, negRep, graffiti, signUp)

• The attestations to an epoch key would be chained together. A hashchain would be formed by the hashes of the attestations.

  • For example, Hash chain is computed by

  const hashChainResult = hash(hashAttestation_3, hash(hashAttestation_2, hash(hashAttestation_1, 0)))

  • So user can not omit any attestation because the circuit requires each attestation in the hashchain to be processed. -> Non-repudiable

  • if user omits an attestation, then the computed hashchain would not match the one in the Unirep contract

See also

• Trees
• Epoch Transition
• User State Transition
• User State Transition Proof