Module ivc::poseidon_8_56_5_3_2::interpreter

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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.

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.