#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#=======================================================================
#
# sha256.py
# ---------
# Simple, pure Python model of the SHA-256 hash function. Used as a
# reference for the HW implementation. The code follows the structure
# of the HW implementation as much as possible.
#
#
# Author: Joachim Strömbergson
# Copyright (c) 2014 SUNET
#
# Redistribution and use in source and binary forms, with or
# without modification, are permitted provided that the following
# conditions are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in
# the documentation and/or other materials provided with the
# distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
#=======================================================================
#-------------------------------------------------------------------
# Python module imports.
#-------------------------------------------------------------------
import sys
#-------------------------------------------------------------------
# Constants.
#-------------------------------------------------------------------
#-------------------------------------------------------------------
# ChaCha()
#-------------------------------------------------------------------
class SHA256():
def __init__(self, verbose = 0):
self.verbose = verbose
self.H = [0] * 8
self.t1 = 0
self.t2 = 0
self.a = 0
self.b = 0
self.c = 0
self.d = 0
self.e = 0
self.f = 0
self.g = 0
self.h = 0
self.w = 0
self.W = [0] * 64
self.k = 0
self.K = [0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2]
def init(self):
self.H = [0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19]
def next(self, block):
self._W_schedule(block)
self._copy_digest()
if self.verbose:
print("State after init:")
self._print_state(0)
for i in range(64):
self._sha256_round(i)
if self.verbose:
self._print_state(i)
self._update_digest()
def get_digest(self):
return self.H
def _copy_digest(self):
self.a = self.H[0]
self.b = self.H[1]
self.c = self.H[2]
self.d = self.H[3]
self.e = self.H[4]
self.f = self.H[5]
self.g = self.H[6]
self.h = self.H[7]
def _update_digest(self):
self.H[0] = (self.H[0] + self.a) & 0xffffffff
self.H[1] = (self.H[1] + self.b) & 0xffffffff
self.H[2] = (self.H[2] + self.c) & 0xffffffff
self.H[3] = (self.H[3] + self.d) & 0xffffffff
self.H[4] = (self.H[4] + self.e) & 0xffffffff
self.H[5] = (self.H[5] + self.f) & 0xffffffff
self.H[6] = (self.H[6] + self.g) & 0xffffffff
self.H[7] = (self.H[7] + self.h) & 0xffffffff
def _print_state(self, round):
print("State at round 0x%02x:" % round)
print("t1 = 0x%08x, t2 = 0x%08x" % (self.t1, self.t2))
print("k = 0x%08x, w = 0x%08x" % (self.k, self.w))
print("a = 0x%08x, b = 0x%08x" % (self.a, self.b))
print("c = 0x%08x, d = 0x%08x" % (self.c, self.d))
print("e = 0x%08x, f = 0x%08x" % (self.e, self.f))
print("g = 0x%08x, h = 0x%08x" % (self.g, self.h))
print("")
def _sha256_round(self, round):
self.k = self.K[round]
self.w = self._next_w(round)
self.t1 = self._T1(self.e, self.f, self.g, self.h, self.k, self.w)
self.t2 = self._T2(self.a, self.b, self.c)
self.h = self.g
self.g = self.f
self.f = self.e
self.e = (self.d + self.t1) & 0xffffffff
self.d = self.c
self.c = self.b
self.b = self.a
self.a = (self.t1 + self.t2) & 0xffffffff
def _next_w(self, round):
if (round < 16):
return self.W[round]
else:
tmp_w = (self._delta1(self.W[14]) +
self.W[9] +
self._delta0(self.W[1]) +
self.W[0]) & 0xffffffff
for i in range(15):
self.W[i] = self.W[(i+1)]
self.W[15] = tmp_w
return tmp_w
def _W_schedule(self, block):
for i in range(16):
self.W[i] = block[i]
def _Ch(self, x, y, z):
return (x & y) ^ (~x & z)
def _Maj(self, x, y, z):
return (x & y) ^ (x & z) ^ (y & z)
def _sigma0(self, x):
return (self._rotr32(x, 2) ^ self._rotr32(x, 13) ^ self._rotr32(x, 22))
def _sigma1(self, x):
return (self._rotr32(x, 6) ^ self._rotr32(x, 11) ^ self._rotr32(x, 25))
def _delta0(self, x):
return (self._rotr32(x, 7) ^ self._rotr32(x, 18) ^ self._shr32(x, 3))
def _delta1(self, x):
return (self._rotr32(x, 17) ^ self._rotr32(x, 19) ^ self._shr32(x, 10))
def _T1(self, e, f, g, h, k, w):
return (h + self._sigma1(e) + self._Ch(e, f, g) + k + w) & 0xffffffff
def _T2(self, a, b, c):
return (self._sigma0(a) + self._Maj(a, b, c)) & 0xffffffff
def _rotr32(self, n, r):
return ((n >> r) | (n << (32 - r))) & 0xffffffff
def _shr32(self, n, r):
return (n >> r)
def compare_digests(digest, expected):
if (digest != expected):
print("Error:")
print("Got:")
print(digest)
print("Expected:")
print(expected)
else:
print("Test case ok.")
#-------------------------------------------------------------------
# main()
#
# If executed tests the ChaCha class using known test vectors.
#-------------------------------------------------------------------
def main():
print("Testing the SHA-256 Python model.")
print("---------------------------------")
print
my_sha256 = SHA256(verbose=1);
# TC1: NIST testcase with message "abc"
TC1_block = [0x61626380, 0x00000000, 0x00000000, 0x00000000,
0x00000000, 0x00000000, 0x00000000, 0x00000000,
0x00000000, 0x00000000, 0x00000000, 0x00000000,
0x00000000, 0x00000000, 0x00000000, 0x00000018]
TC1_expected = [0xBA7816BF, 0x8F01CFEA, 0x414140DE, 0x5DAE2223,
0xB00361A3, 0x96177A9C, 0xB410FF61, 0xF20015AD]
my_sha256.init()
my_sha256.next(TC1_block)
my_digest = my_sha256.get_digest()
compare_digests(my_digest, TC1_expected)
#-------------------------------------------------------------------
# __name__
# Python thingy which allows the file to be run standalone as
# well as parsed from within a Python interpreter.
#-------------------------------------------------------------------
if __name__=="__main__":
# Run the main function.
sys.exit(main())
#=======================================================================
# EOF sha256.py
#=======================================================================
