def _encrypt_block_ints(self, block_ints: List[int]) -> List[int]:
"""Encrypt the text block's integers."""
s = self.__s
# Join individual block bytes into 4 registers.
regs = []
for i in range(0, len(block_ints), 4):
reg = bin_join(block_ints[i:i + 4], BYTE_BITS)
regs.append(reg)
[a, b, c, d] = regs
b = (b + s[0]) % MOD
d = (d + s[1]) % MOD
for i in range(1, R + 1):
t = rotl((b * (2 * b + 1)) % MOD, LG_W, W)
u = rotl((d * (2 * d + 1)) % MOD, LG_W, W)
a = (rotl(a ^ t, u, W) + s[2 * i]) % MOD
c = (rotl(c ^ u, t, W) + s[2 * i + 1]) % MOD
(a, b, c, d) = (b, c, d, a)
a = (a + s[2 * R + 2]) % MOD
c = (c + s[2 * R + 3]) % MOD
cipher_int = bin_join([a, b, c, d], W)
cipher_ints = bin_split(cipher_int, BLOCK_BITS, BYTE_BITS)
return cipher_ints
def _decrypt_block_ints(self, block_ints: List[int]) -> List[int]:
"""Decrypt the cipher block's integers."""
s = self.__s
# Join individual block bytes into 4 registers.
regs = []
for i in range(0, len(block_ints), 4):
reg = bin_join(block_ints[i:i + 4], BYTE_BITS)
regs.append(reg)
[a, b, c, d] = regs
c = (c - s[2 * R + 3]) % MOD
a = (a - s[2 * R + 2]) % MOD
for j in range(R, 0, -1):
(a, b, c, d) = (d, a, b, c)
u = rotl((d * (2 * d + 1)) % MOD, LG_W, W)
t = rotl((b * (2 * b + 1)) % MOD, LG_W, W)
c = (rotr((c - s[2 * j + 1]) % MOD, t, W) ^ u)
a = (rotr((a - s[2 * j]) % MOD, u, W) ^ t)
d = (d - s[1]) % MOD
b = (b - s[0]) % MOD
text_int = bin_join([a, b, c, d], W)
text_ints = bin_split(text_int, BLOCK_BITS, BYTE_BITS)
return text_ints
def __process_block(self, block_ints: List[int],
is_encrypt: bool) -> List[int]:
"""Process the input block's integers (works in both ways)."""
block_int = bin_join(block_ints, BYTE_BITS)
l, r = bin_split(block_int, BLOCK_BITS, SUBBLOCK_BITS)
l, r = _process_subblocks(l, r, self.__p, self.__s, is_encrypt)
output_bin = bin_join([l, r], SUBBLOCK_BITS)
return bin_split(output_bin, BLOCK_BITS, BYTE_BITS)
def __process_block(self, block_ints: List[int]) -> List[int]:
"""Process the input block's integers (works in both ways)."""
block_bin = bin_join(block_ints, BYTE_BITS)
[x1, x2, x3, x4] = bin_split(block_bin, BLOCK_BITS, SUBBLOCK_BITS)
for i in range(ROUNDS_N):
y1, y2, y3, y4 = _ka_layer(x1, x2, x3, x4, self.__subkeys[i][:4])
x1, x2, x3, x4 = _ma_layer(y1, y2, y3, y4, self.__subkeys[i][4:])
y1, y2, y3, y4 = _ka_layer(x1, x3, x2, x4, self.__subkeys[ROUNDS_N])
output_bin = bin_join([y1, y2, y3, y4], SUBBLOCK_BITS)
output_ints = bin_split(output_bin, BLOCK_BITS, BYTE_BITS)
return output_ints
def _generate_subkeys(key_ints: List[int]) -> BlockSubkeys:
"""Generate the subkeys from the given key."""
key_bin = bin_join(key_ints, BYTE_BITS)
subkeys = []
while len(subkeys) < SUBKEYS_N:
subkeys += bin_split(key_bin, KEY_BITS, SUBKEY_BITS)
key_bin = rotl(key_bin, 25, KEY_BITS)
subkeys = subkeys[:SUBKEYS_N]
step = SUBKEYS_N // ROUNDS_N
subkeys = [subkeys[i:i + step] for i in range(0, len(subkeys), step)]
return subkeys
def __get_subkey(self, round_n: int) -> List[int]:
"""Function used for subkey generation by shifted cyclic reading of
32-bit key."""
key_ints = self.__key_ints
bytes_cut = round_n // BYTE_BITS
bits_cut = round_n % BYTE_BITS
# +1 because in order to slice we need to have some extra bits.
req_key_length = bytes_cut + self.key_bytes + 1
while len(key_ints) < req_key_length:
key_ints += key_ints
key_ints = key_ints[bytes_cut:req_key_length]
subkey = bin_join(key_ints, BYTE_BITS)
subkey_width = len(key_ints) * BYTE_BITS
key_bits = self.key_bytes * BYTE_BITS
subkey = bin_slice(subkey, bits_cut, key_bits + bits_cut, subkey_width)
subkey_ints = bin_split(subkey, key_bits, BYTE_BITS)
return subkey_ints