Description

In circuits/src/keccak/mod.rs, the deprecated function KeccakCircuit::compute_proof_id_fixed_length is intended to compute the proofId. However, the calculation is incorrect, as it is missing the circuitId.

Impact

The result of KeccakCircuit::compute_proof_id_fixed_length is incorrect. This function is intended for the fixed-length circuits, which are not intended to be used anymore.

Recommendations

Marking a function as #[deprecated] only causes the compiler to issue a warning on use. If the function is incorrect and will not be fixed, we recommend to cause it to panic (as is done in other places in the fixed-length case) or to remove it.

Remediation

Nebra removed the function from the circuit in the public repository.