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-rwxr-xr-xsrc/model/sha256.py268
1 files changed, 268 insertions, 0 deletions
diff --git a/src/model/sha256.py b/src/model/sha256.py
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+#!/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
+#=======================================================================