Crate p3_poseidon2

The Poseidon2 permutation.

This implementation was based upon the following resources:

• https://github.com/HorizenLabs/poseidon2/blob/main/plain_implementations/src/poseidon2/poseidon2.rs
• https://eprint.iacr.org/2023/323.pdf

Structs

• ExternalLayerConstants
  A struct which holds the constants for the external layer.
• HLMDSMat4
  The 4x4 MDS matrix used by the Horizon Labs implementation of Poseidon2.
• MDSMat4
  The fastest 4x4 MDS matrix.
• Poseidon2
  The Poseidon2 permutation.

Traits

• ExternalLayer
  A trait containing all data needed to implement the external layers of Poseidon2.
• ExternalLayerConstructor
  Initialize an external layer from a set of constants.
• GenericPoseidon2LinearLayers
• InternalLayer
  A trait containing all data needed to implement the internal layers of Poseidon2.
• InternalLayerConstructor
  Initialize an internal layer from a set of constants.

Functions

• add_rc_and_sbox_generic
  A generic method performing the transformation:
• external_initial_permute_state
  A helper method which allow any field to easily implement the initial External Layer.
• external_terminal_permute_state
  A helper method which allow any field to easily implement the terminal External Layer.
• internal_permute_state
  A helper method which allows any field to easily implement Internal Layer. This should only be used in places where performance is not critical.
• matmul_internal
  Given a vector v compute the matrix vector product (1 + diag(v))state with 1 denoting the constant matrix of ones.
• mds_light_permutation
  Implement the matrix multiplication used by the external layer.
• poseidon2_round_numbers_128
  Given a field, a width and an D return the number of full and partial rounds needed to achieve 128 bit security.
• sum_15
  The compiler doesn’t realize that add is associative so we help it out and minimize the dependency chains by hand.
• sum_23
  The compiler doesn’t realize that add is associative so we help it out and minimize the dependency chains by hand.