def mixing_operation(interval, b, c, d):
"""Perform one of four operations, based on the interval. The b, c, and
d arguments are SHA-1 sub-registers.
"""
if 0 <= interval <= 19:
return bitwise_or(bitwise_and(b, c), bitwise_and(bitwise_not(b), d))
elif interval <= 39:
return bitwise_xor(b, c, d)
elif interval <= 59:
return bitwise_or(bitwise_and(b, c), bitwise_and(b, d),
bitwise_and(c, d))
elif interval <= 79:
return bitwise_xor(b, c, d)
else:
raise Exception('Interval out of bounds')
def ff_mult(binary1, binary2):
"""Multiply two binary strings in the GF(2^8) finite field."""
return bitwise_xor(*[
times_x(binary2, power)
for power, bit in reversed(list(enumerate(reversed(binary1))))
if bit == '1'
])
def mixing_operation(interval, b, c, d):
"""Perform one of four operations, based on the interval. The b, c, and
d arguments are SHA-1 sub-registers.
"""
if 0 <= interval <= 19:
return bitwise_or(bitwise_and(b, c),
bitwise_and(bitwise_not(b), d))
elif interval <= 39:
return bitwise_xor(b, c, d)
elif interval <= 59:
return bitwise_or(bitwise_and(b, c),
bitwise_and(b, d),
bitwise_and(c, d))
elif interval <= 79:
return bitwise_xor(b, c, d)
else:
raise Exception('Interval out of bounds')
def feistel_function(half_block, key):
"""Perform confusion and diffusion on a 32-bit binary string."""
expanded = permute(half_block, EXPANSION_PERMUTATION)
xored = bitwise_xor(expanded, key)
b_sections = [xored[place:place + 6] for place in xrange(0, 48, 6)]
c_sections = [apply_s_box(section, S_BOXES[number])
for number, section in enumerate(b_sections)]
return permute(''.join(c_sections), C_PERMUTATION)
def times_x(binary, power=1):
"""Multiply a binary string by X^P in the GF(2^8) finite field."""
for _ in xrange(power):
binary += '0'
if binary[0] == '1':
# X^8 overflow
binary = bitwise_xor(binary, '100011011')
binary = binary[1:]
return binary
def times_x(binary, power=1):
"""Multiply a binary string by X^P in the GF(2^8) finite field."""
for _ in xrange(power):
binary += '0'
if binary[0] == '1':
# X^8 overflow
binary = bitwise_xor(binary, '100011011')
binary = binary[1:]
return binary
def feistel_function(half_block, key):
"""Perform confusion and diffusion on a 32-bit binary string."""
expanded = permute(half_block, EXPANSION_PERMUTATION)
xored = bitwise_xor(expanded, key)
b_sections = [xored[place:place + 6] for place in xrange(0, 48, 6)]
c_sections = [
apply_s_box(section, S_BOXES[number])
for number, section in enumerate(b_sections)
]
return permute(''.join(c_sections), C_PERMUTATION)
def mix_columns(block_matrix, mix_matrix):
"""Multiply two matrixes in the GF(2^8) finite field. The first
argument should be the the current block state, the right argument
a transformation constant (COLUMN_MIX for encryption,
INVERSE_COLUMN_MIX for decryption).
"""
return [[bitwise_xor(*[ff_mult(mix_matrix[row][index],
block_matrix[index][column])
for index in xrange(MATRIX_SIZE)])
for column in xrange(MATRIX_SIZE)]
for row in xrange(MATRIX_SIZE)]
def mix_columns(block_matrix, mix_matrix):
"""Multiply two matrixes in the GF(2^8) finite field. The first
argument should be the the current block state, the right argument
a transformation constant (COLUMN_MIX for encryption,
INVERSE_COLUMN_MIX for decryption).
"""
return [[
bitwise_xor(*[
ff_mult(mix_matrix[row][index], block_matrix[index][column])
for index in xrange(MATRIX_SIZE)
]) for column in xrange(MATRIX_SIZE)
] for row in xrange(MATRIX_SIZE)]
def sha_1_expansion(block):
"""Take a 512 bit binary message and convert it into a series of
32 bit blocks.
"""
sub_blocks = block_split(block, SUB_BLOCKSIZE)
for interval in xrange(len(sub_blocks), SHA_1_INTERVALS):
new_sub_block = bitwise_xor(sub_blocks[interval - 3],
sub_blocks[interval - 8],
sub_blocks[interval - 14],
sub_blocks[interval - 16])
sub_blocks.append(wrap_bits_left(new_sub_block, 1))
return sub_blocks
def sha_1_expansion(block):
"""Take a 512 bit binary message and convert it into a series of
32 bit blocks.
"""
sub_blocks = block_split(block, SUB_BLOCKSIZE)
for interval in xrange(len(sub_blocks), SHA_1_INTERVALS):
new_sub_block = bitwise_xor(sub_blocks[interval - 3],
sub_blocks[interval - 8],
sub_blocks[interval - 14],
sub_blocks[interval - 16])
sub_blocks.append(wrap_bits_left(new_sub_block, 1))
return sub_blocks
def feistel_scheme(binary_text, subkeys):
"""Run the DES algorithm on a each block of the string input
text. The subkeys parameter should be a list of sixteen 48-bit
binary strings.
"""
final_blocks = []
for block in block_split(binary_text):
block = permute(block, INITIAL_PERMUTATION)
left, right = half_string(block)
for key in subkeys:
right, left = bitwise_xor(left, feistel_function(right, key)), right
block = permute(right + left, FINAL_PERMUTATION)
final_blocks.append(block)
return ''.join(final_blocks)
def feistel_scheme(binary_text, subkeys):
"""Run the DES algorithm on a each block of the string input
text. The subkeys parameter should be a list of sixteen 48-bit
binary strings.
"""
final_blocks = []
for block in block_split(binary_text):
block = permute(block, INITIAL_PERMUTATION)
left, right = half_string(block)
for key in subkeys:
right, left = bitwise_xor(left, feistel_function(right,
key)), right
block = permute(right + left, FINAL_PERMUTATION)
final_blocks.append(block)
return ''.join(final_blocks)
def transform_subkey(column, column_number):
"""Obfuscate a key column of length four."""
shifted = rotate(column, 1)
s_boxed = [apply_s_box(byte, S_BOX) for byte in shifted]
return ([bitwise_xor(s_boxed[0], round_constant(column_number))] +
s_boxed[1:])
def add_round_key(block_matrix, key_matrix):
"""XOR two matrixes to produce a single matrix of the same size."""
return [[bitwise_xor(element1, element2)
for element1, element2 in zip(row1, row2)]
for row1, row2 in zip(block_matrix, key_matrix)]
def transform_subkey(column, column_number):
"""Obfuscate a key column of length four."""
shifted = rotate(column, 1)
s_boxed = [apply_s_box(byte, S_BOX) for byte in shifted]
return ([bitwise_xor(s_boxed[0], round_constant(column_number))] +
s_boxed[1:])
def xor_columns(column1, column2):
return [bitwise_xor(element1, element2)
for element1, element2
in zip(column1, column2)]
def add_round_key(block_matrix, key_matrix):
"""XOR two matrixes to produce a single matrix of the same size."""
return [[
bitwise_xor(element1, element2)
for element1, element2 in zip(row1, row2)
] for row1, row2 in zip(block_matrix, key_matrix)]
def xor_columns(column1, column2):
return [
bitwise_xor(element1, element2)
for element1, element2 in zip(column1, column2)
]
def ff_mult(binary1, binary2):
"""Multiply two binary strings in the GF(2^8) finite field."""
return bitwise_xor(*[times_x(binary2, power)
for power, bit in reversed(list(enumerate(reversed(binary1))))
if bit == '1'])
