def crypt(self, input_block, encrypt_mode):
"""
DES Encrypt
INPUT:
input_block, Int or Long (64bit)
encrypt_mode, Bool (True = Encrypt Mode; False = Decrypt Mode)
OUTPUT:
output_block, Int or Long (64bit)
"""
assert (type(input_block) == type(1) or type(input_block) == type(1L))
assert (type(self.key) == type(1) or type(self.key) == type(1L))
assert (type(encrypt_mode) == type(True))
permuted_block = 0
# Initial Permutation
for i in range(0, 64):
permuted_block = bits.set_bit(
permuted_block, i + 1,
bits.get_bit(input_block, self.DES_IP[i], 64), 64)
if DEBUG is True:
print("Permuted: {0}".format(hex(permuted_block)))
# Permuted Input L and R
left_block = bits.get_bits(permuted_block, 1, 32, 64, 32) # 32bits
right_block = bits.get_bits(permuted_block, 33, 64, 64, 32) # 32bits
if DEBUG is True:
print("Permuted L: {0} | Permuted R: {1}".format(
hex(left_block), hex(right_block)))
# Fiestal Rounds
for i in range(0, 16):
temp_left = left_block
left_block = right_block # 32bits, temporary holder
if encrypt_mode is True:
right_block = temp_left ^ self.cipher_function(
right_block, self.key_schedule_list[i])
else:
right_block = temp_left ^ self.cipher_function(
right_block, self.key_schedule_list[15 - i])
# Preoutput Block R'L'
preoutput_block = (right_block << 32) + left_block # 64bits
# Inverse Initial Permutation
output_block = 0
for i in range(0, 64):
output_block = bits.set_bit(
output_block, i + 1,
bits.get_bit(preoutput_block, self.DES_FP[i], 64), 64)
return output_block
def cipher_function(self, r, k):
"""
The DES Cipher Function
INPUTS:
r, Integer or Long (32bit)
k, Int or Long (48bit)
OUTPUT:
Integer or Long (32bit)
"""
assert (type(r) == type(1) or type(r) == type(1L))
assert (type(k) == type(1) or type(k) == type(1L))
expanded_r = 0 # 48bit
for i in range(0, 48):
expanded_r = bits.set_bit(expanded_r, i + 1,
bits.get_bit(r, self.DES_E[i], 32), 48)
output = expanded_r ^ k # 48bit in size
# Substitution Boxes
chunks = [] # Each chunk is 6 bits
for i in range(0, 8):
chunks.append(bits.get_bits(output, i * 6 + 1, (i + 1) * 6, 48, 6))
chunk_row = lambda chunk: (bits.get_bit(
chunk, 1, 6) << 1) + bits.get_bit(chunk, 6, 6) # 2 Bit Integer
chunk_col = lambda chunk: bits.get_bits(chunk, 2, 5, 6, 4
) # 4 Bit Integer
substitute_chunk = lambda chunk, box: \
box[chunk_row(chunk)][chunk_col(chunk)]
output = 0 # 32bit
for i in range(0, 8):
output += substitute_chunk(chunks[i], self.DES_S[i]) << (
(7 - i) * 4)
final_output = 0 #32bit
for i in range(0, 32):
final_output = bits.set_bit(
final_output, i + 1, bits.get_bit(output, self.DES_P[i], 32),
32)
return final_output
def crypt(self, input_block, encrypt_mode):
"""
DES Encrypt
INPUT:
input_block, Int or Long (64bit)
encrypt_mode, Bool (True = Encrypt Mode; False = Decrypt Mode)
OUTPUT:
output_block, Int or Long (64bit)
"""
assert(type(input_block) == type(1) or type(input_block) == type(1L))
assert(type(self.key) == type(1) or type(self.key) == type(1L))
assert(type(encrypt_mode) == type(True))
permuted_block = 0
# Initial Permutation
for i in range(0, 64):
permuted_block = bits.set_bit(permuted_block, i+1, bits.get_bit(input_block, self.DES_IP[i], 64), 64)
if DEBUG is True:
print("Permuted: {0}".format(hex(permuted_block)))
# Permuted Input L and R
left_block = bits.get_bits(permuted_block, 1, 32, 64, 32) # 32bits
right_block = bits.get_bits(permuted_block, 33, 64, 64, 32) # 32bits
if DEBUG is True:
print("Permuted L: {0} | Permuted R: {1}".format(hex(left_block), hex(right_block)))
# Fiestal Rounds
for i in range(0, 16):
temp_left = left_block
left_block = right_block # 32bits, temporary holder
if encrypt_mode is True:
right_block = temp_left ^ self.cipher_function(right_block, self.key_schedule_list[i])
else:
right_block = temp_left ^ self.cipher_function(right_block, self.key_schedule_list[15-i])
# Preoutput Block R'L'
preoutput_block = (right_block << 32) + left_block # 64bits
# Inverse Initial Permutation
output_block = 0
for i in range(0, 64):
output_block = bits.set_bit(output_block, i+1, bits.get_bit(preoutput_block, self.DES_FP[i], 64), 64)
return output_block
def cipher_function(self, r, k):
"""
The DES Cipher Function
INPUTS:
r, Integer or Long (32bit)
k, Int or Long (48bit)
OUTPUT:
Integer or Long (32bit)
"""
assert(type(r) == type(1) or type(r) == type(1L))
assert(type(k) == type(1) or type(k) == type(1L))
expanded_r = 0 # 48bit
for i in range(0, 48):
expanded_r = bits.set_bit(expanded_r, i+1, bits.get_bit(r, self.DES_E[i], 32), 48)
output = expanded_r ^ k # 48bit in size
# Substitution Boxes
chunks = [] # Each chunk is 6 bits
for i in range(0, 8):
chunks.append(bits.get_bits(output, i * 6 + 1, (i + 1) * 6, 48, 6))
chunk_row = lambda chunk: (bits.get_bit(chunk, 1, 6) << 1) + bits.get_bit(chunk, 6, 6) # 2 Bit Integer
chunk_col = lambda chunk: bits.get_bits(chunk, 2, 5, 6, 4) # 4 Bit Integer
substitute_chunk = lambda chunk, box: \
box[chunk_row(chunk)][chunk_col(chunk)]
output = 0 # 32bit
for i in range(0, 8):
output += substitute_chunk(chunks[i], self.DES_S[i]) << ((7 - i) * 4)
final_output = 0 #32bit
for i in range(0, 32):
final_output = bits.set_bit(final_output, i+1, bits.get_bit(output, self.DES_P[i], 32), 32)
return final_output