#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#=======================================================================
#
# sha1.py
# ---------
# Simple, pure Python model of the SHA-1 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
# (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 SHA1():
def __init__(self, verbose = 0):
self.verbose = verbose
self.H = [0] * 5
self.T = 0
self.a = 0
self.b = 0
self.c = 0
self.d = 0
self.e = 0
self.W = [0] * 80
self.k = 0
def init(self):
self.H = [0x67452301, 0xefcdab89, 0x98badcfe,
0x10325476, 0xc3d2e1f0]
def next(self, block):
self._W_schedule(block)
self._copy_digest()
for i in range(80):
self._sha1_round(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]
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
def _sha1_round(self, round):
if round <= 19:
self.k = 0x5a827999
self.f = self._Ch(self.b, self.c, self.d)
elif 20 <= round <= 39:
self.k = 0x6ed9eba1
self.f = self._Parity(self.b, self.c, self.d)
elif 40 <= round <= 59:
self.k = 0x8f1bbcdc
self.f = self._Maj(self.b, self.c, self.d)
elif 60 <= round <= 79:
self.k = 0xca62c1d6
self.f = self._Parity(self.b, self.c, self.d)
if self.verbose:
print("Round %0d" % round)
print("Round input values:")
print("a = 0x%08x, b = 0x%08x, c = 0x%08x" % (self.a, self.b, self.c))
print("d = 0x%08x, e = 0x%08x" % (self.d, self.e))
print("f = 0x%08x, k = 0x%08x, w = 0x%08x" % (self.f, self.k, self.W[round]))
self.T = (self._rotl32(self.a, 5) + self.f + self.e + self.k + self.W[round]) & 0xffffffff
self.e = self.d
self.d = self.c
self.c = self._rotl32(self.b, 30)
self.b = self.a
self.a = self.T
if self.verbose:
print("Round output values:")
print("a = 0x%08x, b = 0x%08x, c = 0x%08x" % (self.a, self.b, self.c))
print("d = 0x%08x, e = 0x%08x" % (self.d, self.e))
print("")
def _W_schedule(self, block):
# Expand the block into 80 words before round operations.
for i in range(80):
if (i < 16):
self.W[i] = block[i]
else:
self.W[i] = self._rotl32((self.W[(i - 3)] ^ self.W[(i - 8)] ^
self.W[(i - 14)] ^ self.W[(i - 16)]), 1)
if (self.verbose):
print("W after schedule:")
for i in range(80):
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 _Parity(self, x, y, z):
return (x ^ y ^ z)
def _rotl32(self, n, r):
return ((n << r) | (n >> (32 - r))) & 0xffffffff
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_sha1 = SHA1(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 = [0xa9993e36, 0x4706816a, 0xba3e2571,
0x7850c26c, 0x9cd0d89d]
my_sha1.init()
my_sha1.next(TC1_block)
my_digest = my_sha1.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 sha1.py
#=======================================================================
