def padKey(self, key_bytes):
'''Pads the used key with zeroes on the right until it meets the expected
hash input length. Doesn't return the padded key, just changes it
in-place.'''
paddedKey = MyBitArray()
paddedKey.FromBytes(key_bytes)
if len(paddedKey) < BrownThomasHMAC.expectedBlockLength:
padding = [0] * (len(paddedKey) - BrownThomasHMAC.expectedBlockLength)
padding.extend(paddedKey.bits)
paddedKey.FromBits(padding)
elif len(paddedKey) > BrownThomasHMAC.expectedBlockLength:
paddedKey.bits = paddedKey.bits[:BrownThomasHMAC.expectedBlockLength]
return paddedKey
def ProcessPermutation(self, bit_array, permutation_box, is_reversed = False):
# Make resulting bit array
result = MyBitArray()
# Process the permutation
if is_reversed == False:
for x in permutation_box:
result.append(bit_array[x - 1])
else:
# Reverse the permutation
result.bits = [0] * len(bit_array)
for i in range(len(permutation_box)):
result[permutation_box[i] - 1] = bit_array[i]
return result
def CreateInitializationVector(self):
bitLength = 0
initializationVector = bytearray()
while bitLength < self.expectedBlockLength:
appendage = randint(0, 255)
initializationVector.append(appendage)
bitLength += appendage.bit_length()
if bitLength >= self.expectedBlockLength:
break
resultBitArray = MyBitArray()
resultBitArray.FromBytes(initializationVector)
# Truncate result to expectedBlockLength # of bits
resultBitArray.bits = resultBitArray.bits[:self.expectedBlockLength]
return resultBitArray
