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.