37 lines
1.3 KiB
Python
37 lines
1.3 KiB
Python
"""Mimc hash function."""
|
|
"""
|
|
This module adapted from https://github.com/OlegJakushkin/deepblockchains/blob/master/vdf/mimc/python/mimc.py by Sourabh Niyogi https://github.com/sourabhniyogi
|
|
|
|
This program is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation, either version 3 of the License, or
|
|
(at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program. If not, see <https://www.gnu.org/licenses/>.
|
|
"""
|
|
modulus = 2**256 - 2**32 * 351 + 1
|
|
little_fermat_expt = (modulus*2-1)//3
|
|
round_constants = [(i**7) ^ 42 for i in range(64)]
|
|
|
|
|
|
def forward_mimc(inp: int, steps: int) -> int:
|
|
for i in range(1,steps):
|
|
inp = (inp**3 + round_constants[i % len(round_constants)]) % modulus
|
|
return inp
|
|
|
|
|
|
def reverse_mimc(input_data: int, steps: int) -> int:
|
|
rtrace = input_data
|
|
|
|
for i in range(steps - 1, 0, -1):
|
|
rtrace = pow(rtrace-round_constants[i%len(round_constants)],
|
|
little_fermat_expt, modulus)
|
|
return rtrace
|
|
|