package bls12-381-hash
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bls12-381-hash
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package bls12-381-hash
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Implementation of an instantiation of Poseidon over the scalar field of BLS12-381 for a security of 128 bits and with the permutation x^5. The parameters of the instantiation are:
- state size = 3
- number of full rounds = 8
- number partial rounds = 56
- the partial rounds run the sbox on the last element of the state
These parameters have been generated using security_parameters.ml from Mec.
The linear layer constants and the round keys can be generated using generate_ark.ml and generate_mds.sage from Mec. The constants must be loaded at the top level using Poseidon128.constants_init.
The current implementation only provides the functions to run a permutation. The user is responsible to build a hash function on top of it.
val constants_init : Bls12_381.Fr.t array -> Bls12_381.Fr.t array array -> unitconstants_init ark mds initializes the constants for Poseidon.
Warnings:
- The function does not verify the parameters are secured
- This function must be called before calling
init,apply_permutationandget
val init : Bls12_381.Fr.t -> Bls12_381.Fr.t -> Bls12_381.Fr.t -> ctxtinit a b c returns a new context with an initialised state with the value [a, b, c].
val apply_permutation : ctxt -> unitapply_permutation ctxt applies a permutation on the state. The context is modified.
val get : ctxt -> Bls12_381.Fr.t * Bls12_381.Fr.t * Bls12_381.Fr.tget ctxt returns the state of the permutation