Adding a Python model for the SHA256 core.

1 files changed, 268 insertions, 0 deletions

diff --git a/src/model/sha256.py b/src/model/sha256.py
new file mode 100755
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+++ 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
+#=======================================================================