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| from bitarray import bitarray
class MyDES:
def __init__(self):
self.child_keys = []
@staticmethod
def _bit_encode(s: str) -> str:
"""
将字符串转换为01字符串的形式
"""
return bitarray(
''.join([bin(int('1' + hex(c)[2:], 16))[3:]
for c in s.encode('utf-8')])).to01()
def _str_to__fixed_len_bit(self, s: str, length: int) -> str:
"""
将字符串转变为固定长度的01字符串
:param s: 要转换的字符串
:param length: 目标长度
:return: 长度为length的01字符串
"""
bit_iv = self._bit_encode(s)
while len(bit_iv) < length:
bit_iv += '0'
return bit_iv[: length]
@staticmethod
def _bit_decode(s: list):
return ''.join([chr(i) for i in [int(b, 2) for b in s]])
@staticmethod
def _negate(s: str):
result = ""
try:
for i in s:
result += '0' if i == '1' else '1'
return result
except:
print("密钥错误")
raise
@staticmethod
def _replace_block(block: str, replace_table: tuple) -> str:
"""
对单个块进行置换
Args:
block: str, 要进行转换的64位长的01字符串
replace_table: 转换表
Return:
返回转换后的字符串
"""
result = ""
for i in replace_table:
try:
result += block[i - 1]
except IndexError:
print(i)
raise
return result
def _processing_encode_input(self, enter: str) -> list:
"""
将输入的字符串转换为二进制形式，并没64位为一组进行分割
"""
result = []
bit_string = self._bit_encode(enter)
if len(bit_string) % 64 != 0:
for i in range(64 - len(bit_string) % 64):
bit_string += '0'
for i in range(len(bit_string) // 64):
result.append(bit_string[i * 64: i * 64 + 64])
return result
@staticmethod
def _processing_decode_input(enter: str) -> list:
result = []
try:
input_list = enter.split("0x")[1:]
int_list = [int("0x" + i, 16) for i in input_list]
for i in int_list:
bin_data = str(bin(i))[2:]
while len(bin_data) < 64:
bin_data = '0' + bin_data
result.append(bin_data)
return result
except Exception as e:
raise
def _key_conversion(self, key: str):
"""
将64位原始密钥转换为56位的密钥，并进行一次置换
"""
key = self._bit_encode(key)
while len(key) < 64:
key += '0'
first_key = key[:64]
key_replace_table = (
57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18,
10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36,
63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22,
14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4
)
return self._replace_block(first_key, key_replace_table)
def _spin_key(self, key: str):
"""
旋转获得子密钥
"""
kc = self._key_conversion(key)
first, second = kc[0: 28], kc[28: 56]
spin_table = (1, 2, 4, 6, 8, 10, 12, 14, 15, 17, 19, 21, 23, 25, 27, 28)
for i in range(1, 17):
first_after_spin = first[spin_table[i - 1]:] + first[:spin_table[i - 1]]
second_after_spin = second[spin_table[i - 1]:] + second[:spin_table[i - 1]]
yield first_after_spin + second_after_spin
def _key_selection_replacement(self, key: str):
"""
通过选择置换得到48位的子密钥
"""
self.child_keys = []
key_select_table = (
14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10,
23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2,
41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48,
44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32
)
for child_key56 in self._spin_key(key):
self.child_keys.append(self._replace_block(child_key56, key_select_table))
def _init_replace_block(self, block: str):
"""
对一个块进行初态置换
"""
replace_table = (
58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6,
64, 56, 48, 40, 32, 24, 16, 8,
57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7
)
return self._replace_block(block, replace_table)
def _end_replace_block(self, block: str) -> str:
"""
对某一个块进行终态转换
"""
replace_table = (
40, 8, 48, 16, 56, 24, 64, 32,
39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25
)
return self._replace_block(block, replace_table)
@staticmethod
def _block_extend(block: str) -> str:
"""
拓展置换
"""
extended_block = ""
extend_table = (
32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9, 10, 11, 12, 13,
12, 13, 14, 15, 16, 17,
16, 17, 18, 19, 20, 21,
20, 21, 22, 23, 24, 25,
24, 25, 26, 27, 28, 29,
28, 29, 30, 31, 32, 1
)
for i in extend_table:
extended_block += block[i - 1]
return extended_block
@staticmethod
def _not_or(a: str, b: str) -> str:
"""
对两个01字符串做异或
"""
result = ""
size = len(a) if len(a) < len(a) else len(b)
for i in range(size):
result += '0' if a[i] == b[i] else '1'
return result
def _s_box_replace(self, block48: str) -> str:
"""
S盒置换，将48位的输入转换为32位输出
"""
s_box_table = (
(
(14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7),
(0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8),
(4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0),
(15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13),
),
(
(15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10),
(3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5),
(0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15),
(13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9),
),
(
(10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8),
(13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1),
(13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7),
(1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12),
),
(
(7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15),
(13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9),
(10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4),
(3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14),
),
(
(2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9),
(14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6),
(4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14),
(11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3),
),
(
(12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11),
(10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8),
(9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6),
(4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13),
),
(
(4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1),
(13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6),
(1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2),
(6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12),
),
(
(13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7),
(1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2),
(7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8),
(2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11),
)
)
result = ""
for i in range(8):
row_bit = (block48[i * 6] + block48[i * 6 + 5]).encode("utf-8")
line_bit = (block48[i * 6 + 1: i * 6 + 5]).encode("utf-8")
row = int(row_bit, 2)
line = int(line_bit, 2)
data = s_box_table[i][row][line]
no_full = str(bin(data))[2:]
while len(no_full) < 4:
no_full = '0' + no_full
result += no_full
return result
def _s_box_compression(self, num: int, block48: str) -> str:
"""
对经过拓展置换后的48位01串进行S盒压缩，有两部：
1. 与key做异或
2. 根据S盒压缩表经48位压缩为36位
Args:
num: 第几次迭代
block48: right
Return:
返回经过S盒压缩后的32位01字符串
"""
result_not_or = self._not_or(block48, self.child_keys[num])
return self._s_box_replace(result_not_or)
def _p_box_replacement(self, block32: str) -> str:
"""
P盒置换
Return:
返回经过P盒置换后的32位01串
"""
p_box_replace_table = (
16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10,
2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25,
)
return self._replace_block(block32, p_box_replace_table)
def _f_function(self, right: str, is_decode: bool, num: int):
right = self._block_extend(right)
if is_decode:
sbc_result = self._s_box_compression(15 - num, right)
else:
sbc_result = self._s_box_compression(num, right)
return self._p_box_replacement(sbc_result)
def _iteration(self, block: str, key: str, is_decode: bool) -> str:
self._key_selection_replacement(key)
for i in range(16):
left, right = block[0: 32], block[32: 64]
next_left = right
f_result = self._f_function(right, is_decode, i)
right = self._not_or(left, f_result)
block = next_left + right
return block[32:] + block[:32]
def encode(self, enter: str, key: str):
result = ""
blocks = self._processing_encode_input(enter)
for block in blocks:
irb_result = self._init_replace_block(block)
block_result = self._iteration(irb_result, key, is_decode=False)
block_result = self._end_replace_block(block_result)
result += str(hex(int(block_result.encode(), 2)))
return result
def encode_by_cbc(self, enter: str, des_key: str, iv: str):
"""
使用 CBC 模式进行 DES加密
:param enter: 明文
:param des_key: 密钥
:param iv: CBC模式中的因子
:return: 加密后的十六进制格式密文串
"""
bit_iv = self._str_to__fixed_len_bit(iv, 64)
result = ""
blocks = self._processing_encode_input(enter)
previous = bit_iv
for block in blocks:
block = self._not_or(block, previous)
irb_result = self._init_replace_block(block)
block_result = self._iteration(irb_result, des_key, is_decode=False)
block_result = self._end_replace_block(block_result)
previous = block_result
result += str(hex(int(block_result.encode(), 2)))
return result
def decode(self, cipher_text: str, key: str):
result = []
blocks = self._processing_decode_input(cipher_text)
for block in blocks:
irb_result = self._init_replace_block(block)
block_result = self._iteration(irb_result, key, is_decode=True)
block_result = self._end_replace_block(block_result)
for i in range(0, len(block_result), 8):
result.append(block_result[i: i+8])
return self._bit_decode(result)
def decode_by_cbc(self, cipher_text: str, des_key: str, iv: str):
bit_iv = self._str_to__fixed_len_bit(iv, 64)
result = []
blocks = self._processing_decode_input(cipher_text)
previous = bit_iv
for block in blocks:
irb_result = self._init_replace_block(block)
block_result = self._iteration(irb_result, des_key, is_decode=True)
block_result = self._end_replace_block(block_result)
block_result = self._not_or(block_result, previous)
previous = block
for i in range(0, len(block_result), 8):
result.append(block_result[i: i+8])
return self._bit_decode(result)
if __name__ == '__main__':
key = "hahahha"
iv = "this is iv"
md = MyDES()
des_encode = md.encode("junebao.top", key)
print("DES加密后的数据为：" + des_encode)
print(f"解密出的数据为：" + md.decode(des_encode, key))
cbc_encode = md.encode_by_cbc('http://blog.junebao.top', des_key=key, iv=iv)
print(f"CBC mode encryption： {cbc_encode}")
print(f"CBC mode decrypt： {md.decode_by_cbc(cbc_encode, des_key=key, iv=iv)}")
|