Module ivc::poseidon_8_56_5_3_2::interpreter

Implement an interpreter for a specific instance of the Poseidon inner permutation. The Poseidon construction is defined in the paper “Poseidon: A New Hash Function”. The Poseidon instance works on a state of size STATE_SIZE and is designed to work with full and partial rounds. As a reminder, the Poseidon permutation is a mapping from F^STATE_SIZE to F^STATE_SIZE. The user is responsible to provide the correct number of full and partial rounds for the given field and the state. Also, it is hard-coded that the substitution is 5. The user must verify that 5 is coprime with p - 1 where p is the order the field. The constants and matrix can be generated the file poseidon/src/pasta/params.sage

Traits

• PoseidonParams
  Represents the parameters of the instance of the Poseidon permutation. Constants are the round constants for each round, and MDS is the matrix used by the linear layer. The type is parametrized by the field, the state size, and the total number of rounds.

Functions

• apply_permutation
  Apply the HADES-based Poseidon to the state. The environment has to be initialized with the input values. It mimicks the version described in the paper “Poseidon: A New Hash Function”, figure 2. The construction first starts with NB_FULL_ROUND/2 full rounds, then NB_PARTIAL_ROUND partial rounds, and finally NB_FULL_ROUND/2 full rounds.
• poseidon_circuit
  Populates and checks one poseidon invocation.