104 lines
3.9 KiB
Python
104 lines
3.9 KiB
Python
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class Gost(object):
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def __init__(self, key, sbox):
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self._key = 0
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self._subkeys = None
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self.key = key
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self.sbox = sbox
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@property
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def key(self) -> int:
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return self._key
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@key.setter
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def key(self, key: str) -> None:
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assert len(key) <= 32
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encoded_key = key.encode("ascii")
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for index in range(31, -1, -1):
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self._key |= encoded_key[index] << (index * 8)
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self._subkeys = [(self._key >> (32 * index)) & 0xFFFFFFFF for index in range(8)]
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def _function(self, part: int, key: int) -> int:
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part = (part + key) % (1 << 32)
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temp = 0
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for index in range(8):
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temp |= ((self.sbox[index][(part >> (4 * index)) & 0b1111]) << (4 * index))
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return ((temp >> 11) | (temp << 21)) & 0xFFFFFFFF
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def encrypt_part(self, message_part: int) -> int:
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left = message_part >> 32
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right = message_part & 0xFFFFFFFF
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for index in range(24):
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left, right = right, left ^ self._function(right, self._subkeys[index % 8])
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for index in range(8):
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left, right = right, left ^ self._function(right, self._subkeys[7 - index])
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return (left << 32) | right
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def decrypt_part(self, crypted_message_part: int) -> int:
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left = crypted_message_part >> 32
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right = crypted_message_part & 0xFFFFFFFF
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for index in range(8):
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left, right = right ^ self._function(left, self._subkeys[index]), left
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for index in range(24):
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left, right = right ^ self._function(left, self._subkeys[(7 - index) % 8]), left
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return (left << 32) | right
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def encrypt(self, message: str) -> int:
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encoded_message = message.encode("ascii")
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encrypted_message = 0
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for part_index in range(len(message) // 8 + 1 * (len(message) % 8 != 0)):
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binary_part = 0
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for letter_index in range(8):
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letter = 0x0000
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if (letter_index + part_index * 8 < len(message)):
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letter = encoded_message[letter_index + part_index * 8]
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binary_part = (binary_part << 8) | letter
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encrypted_message = (encrypted_message << 64) | self.encrypt_part(binary_part)
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return encrypted_message
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def decrypt(self, encrypted_message: int) -> str:
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decrypted_message = ""
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for index in range(len(bin(encrypted_message)[2:]) // 64, -1, -1):
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binary_part = (encrypted_message >> (64 * index)) & 0xFFFFFFFFFFFFFFFF
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decrypted_binary_part = self.decrypt_part(binary_part)
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for letter_index in range(8):
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decrypted_message += chr((decrypted_binary_part >> ((7 - letter_index) * 8)) & 0xFF)
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return decrypted_message
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def main():
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sbox = [
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[0x4, 0xA, 0x9, 0x2, 0xD, 0x8, 0x0, 0xE, 0x6, 0xB, 0x1, 0xC, 0x7, 0xF, 0x5, 0x3],
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[0xE, 0xB, 0x4, 0xC, 0x6, 0xD, 0xF, 0xA, 0x2, 0x3, 0x8, 0x1, 0x0, 0x7, 0x5, 0x9],
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[0x5, 0x8, 0x1, 0xD, 0xA, 0x3, 0x4, 0x2, 0xE, 0xF, 0xC, 0x7, 0x6, 0x0, 0x9, 0xB],
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[0x7, 0xD, 0xA, 0x1, 0x0, 0x8, 0x9, 0xF, 0xE, 0x4, 0x6, 0xC, 0xB, 0x2, 0x5, 0x3],
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[0x6, 0xC, 0x7, 0x1, 0x5, 0xF, 0xD, 0x8, 0x4, 0xA, 0x9, 0xE, 0x0, 0x3, 0xB, 0x2],
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[0x4, 0xB, 0xA, 0x0, 0x7, 0x2, 0x1, 0xD, 0x3, 0x6, 0x8, 0x5, 0x9, 0xC, 0xF, 0xE],
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[0xD, 0xB, 0x4, 0x1, 0x3, 0xF, 0x5, 0x9, 0x0, 0xA, 0xE, 0x7, 0x6, 0x8, 0x2, 0xC],
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[0x1, 0xF, 0xD, 0x0, 0x5, 0x7, 0xA, 0x4, 0x9, 0x2, 0x3, 0xE, 0x6, 0xB, 0x8, 0xC]
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]
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message = "Lorem ipsum dolor sit amet, consectetur adipiscing elit."
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key = "zqHqtbGwB41OOsm5EeGmG0VKeJWrnhML"
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gost = Gost(key, sbox)
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crypted_message = gost.encrypt(message)
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encrypted_message = gost.decrypt(crypted_message)
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print("Original message: ", message)
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print("Crypted: ", crypted_message)
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print("Encrypted message: ", encrypted_message)
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if __name__ == "__main__":
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main()
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