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| -rwxr-xr-x | src/model/sha256.py | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/src/model/sha256.py b/src/model/sha256.py new file mode 100755 index 0000000..a0535ba --- /dev/null +++ b/src/model/sha256.py @@ -0,0 +1,268 @@ +#!/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 Strombergson +# (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.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 _W_schedule(self, block): + for i in range(64): + if (i < 16): + self.W[i] = block[i] + else: + self.W[i] = (self._delta1(self.W[(i - 2)]) + + self.W[(i - 7)] + + self._delta0(self.W[(i - 15)]) + + self.W[(i - 16)]) & 0xffffffff + if (self.verbose): + print("W after schedule:") + for i in range(64): + print("W[%02d] = 0x%08x" % (i, self.W[i])) + print("") + + + 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 +#======================================================================= |