# coding: utf-8
# PyGOST -- Pure Python GOST cryptographic functions library
-# Copyright (C) 2015-2016 Sergey Matveev <stargrave@stargrave.org>
+# Copyright (C) 2015-2017 Sergey Matveev <stargrave@stargrave.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
from functools import partial
-from pygost.gost3413 import pad1
from pygost.gost3413 import pad2
+from pygost.gost3413 import pad_size
+from pygost.gost3413 import unpad2
from pygost.utils import hexdec
from pygost.utils import strxor
-from pygost.utils import xrange
+from pygost.utils import xrange # pylint: disable=redefined-builtin
KEYSIZE = 32
:param s: S-box
:param _in: 32-bit word
- :return: substituted 32-bit word
+ :returns: substituted 32-bit word
"""
return (
(s[0][(_in >> 0) & 0x0F] << 0) +
:param bytes key: 256-bit encryption key
:param ns: N1 and N2 integers
:type ns: (int, int)
- :return: resulting N1 and N2
+ :returns: resulting N1 and N2
:rtype: (int, int)
"""
s = SBOXES[sbox]
:param bytes key: encryption key
:param data: plaintext
:type data: bytes, multiple of BLOCKSIZE
- :param func action: encrypt/decrypt
+ :param func action: "encrypt"/"decrypt"
:param sbox: S-box parameters to use
:type sbox: str, SBOXES'es key
- :return: ciphertext
+ :returns: ciphertext
:rtype: bytes
"""
validate_key(key)
result.append(ns2block(action(
sbox, key, block2ns(data[i:i + BLOCKSIZE])
)))
- return b''.join(result)
+ return b"".join(result)
ecb_encrypt = partial(ecb, action=encrypt)
ecb_decrypt = partial(ecb, action=decrypt)
-def cbc_encrypt(key, data, iv=8 * b'\x00', pad=True, sbox=DEFAULT_SBOX):
+def cbc_encrypt(key, data, iv=8 * b"\x00", pad=True, sbox=DEFAULT_SBOX):
""" CBC encryption mode of operation
:param bytes key: encryption key
:type bool pad: perform ISO/IEC 7816-4 padding
:param sbox: S-box parameters to use
:type sbox: str, SBOXES'es key
- :return: ciphertext
+ :returns: ciphertext
:rtype: bytes
34.13-2015 padding method 2 is used.
ciphertext.append(ns2block(encrypt(sbox, key, block2ns(
strxor(ciphertext[-1], data[i:i + BLOCKSIZE])
))))
- return b''.join(ciphertext)
+ return b"".join(ciphertext)
def cbc_decrypt(key, data, pad=True, sbox=DEFAULT_SBOX):
:type bool pad: perform ISO/IEC 7816-4 unpadding after decryption
:param sbox: S-box parameters to use
:type sbox: str, SBOXES'es key
- :return: plaintext
+ :returns: plaintext
:rtype: bytes
"""
validate_key(key)
data[i - BLOCKSIZE:i],
))
if pad:
- last_block = bytearray(plaintext[-1])
- pad_index = last_block.rfind(b'\x80')
- if pad_index == -1:
- raise ValueError("Invalid padding")
- for c in last_block[pad_index + 1:]:
- if c != 0:
- raise ValueError("Invalid padding")
- plaintext[-1] = bytes(last_block[:pad_index])
- return b''.join(plaintext)
-
-
-def cnt(key, data, iv=8 * b'\x00', sbox=DEFAULT_SBOX):
+ plaintext[-1] = unpad2(plaintext[-1], BLOCKSIZE)
+ return b"".join(plaintext)
+
+
+def cnt(key, data, iv=8 * b"\x00", sbox=DEFAULT_SBOX):
""" Counter mode of operation
:param bytes key: encryption key
:type iv: bytes, BLOCKSIZE length
:param sbox: S-box parameters to use
:type sbox: str, SBOXES'es key
- :return: ciphertext
+ :returns: ciphertext
:rtype: bytes
For decryption you use the same function again.
if not data:
raise ValueError("No data supplied")
n2, n1 = encrypt(sbox, key, block2ns(iv))
- size = len(data)
- data = pad1(data, BLOCKSIZE)
gamma = []
- for _ in xrange(0, len(data), BLOCKSIZE):
+ for _ in xrange(0, len(data) + pad_size(len(data), BLOCKSIZE), BLOCKSIZE):
n1 = addmod(n1, C2, 2 ** 32)
n2 = addmod(n2, C1, 2 ** 32 - 1)
gamma.append(ns2block(encrypt(sbox, key, (n1, n2))))
- return strxor(b''.join(gamma), data[:size])
+ return strxor(b"".join(gamma), data)
MESH_CONST = hexdec("6900722264C904238D3ADB9646E92AC418FEAC9400ED0712C086DCC2EF4CA92B")
return key, iv
-def cfb_encrypt(key, data, iv=8 * b'\x00', sbox=DEFAULT_SBOX, mesh=False):
+def cfb_encrypt(key, data, iv=8 * b"\x00", sbox=DEFAULT_SBOX, mesh=False):
""" CFB encryption mode of operation
:param bytes key: encryption key
:param sbox: S-box parameters to use
:type sbox: str, SBOXES'es key
:param bool mesh: enable key meshing
- :return: ciphertext
+ :returns: ciphertext
:rtype: bytes
"""
validate_key(key)
validate_sbox(sbox)
if not data:
raise ValueError("No data supplied")
- size = len(data)
- data = pad1(data, BLOCKSIZE)
ciphertext = [iv]
- for i in xrange(0, len(data), BLOCKSIZE):
+ for i in xrange(0, len(data) + pad_size(len(data), BLOCKSIZE), BLOCKSIZE):
if mesh and i >= MESH_MAX_DATA and i % MESH_MAX_DATA == 0:
key, iv = meshing(key, ciphertext[-1], sbox=sbox)
ciphertext.append(strxor(
data[i:i + BLOCKSIZE],
ns2block(encrypt(sbox, key, block2ns(ciphertext[-1]))),
))
- return b''.join(ciphertext[1:])[:size]
+ return b"".join(ciphertext[1:])
-def cfb_decrypt(key, data, iv=8 * b'\x00', sbox=DEFAULT_SBOX, mesh=False):
+def cfb_decrypt(key, data, iv=8 * b"\x00", sbox=DEFAULT_SBOX, mesh=False):
""" CFB decryption mode of operation
:param bytes key: encryption key
:param sbox: S-box parameters to use
:type sbox: str, SBOXES'es key
:param bool mesh: enable key meshing
- :return: ciphertext
+ :returns: ciphertext
:rtype: bytes
"""
validate_key(key)
validate_sbox(sbox)
if not data:
raise ValueError("No data supplied")
- size = len(data)
- data = pad1(data, BLOCKSIZE)
plaintext = []
data = iv + data
- for i in xrange(BLOCKSIZE, len(data), BLOCKSIZE):
+ for i in xrange(BLOCKSIZE, len(data) + pad_size(len(data), BLOCKSIZE), BLOCKSIZE):
if (
mesh and
(i - BLOCKSIZE) >= MESH_MAX_DATA and
data[i:i + BLOCKSIZE],
ns2block(encrypt(sbox, key, block2ns(data[i - BLOCKSIZE:i]))),
))
- return b''.join(plaintext)[:size]
+ return b"".join(plaintext)