DES的加密与解密算法（Python实现）
密码学实验：实现了DES的简单的加密和解密算法，DES算法的相关资料网上很多，这里不再赘述，仅仅贴出源代码给大家分享，源码中包含很多汉字注释，相信大家都是可以读懂的。
为了方便阅读和理解DES算法的原理，这里我将代码进行了模块化，分为了四个模块：密钥生成模块、F函数模块、DES加密模块、DES解密模块。
注：DES的加密算法和解密算法几乎是一模一样的，仅仅是密钥的使用顺序不同，所以模块的代码也几乎没有什么区别。输入输出要求是16个十六进制的字符，刚好是64bit！
转载请注明出处：https://www.cnblogs.com/wangyanzhong123/p/10575739.html
密钥生成模块：
MaxTime = 16
#生成子密钥的置换表1，将64位的密钥转换为56位
key_table1=[ 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 ]
#生成子密钥的置换表2，将56位的密钥转换为48位
key_table2=[ 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 ] def Listmove(l, step): #将列表中的元素循环左移
return l[step:] + l[:step] def Subkey(key): #生成子密钥
keyresult = []
key0 = [0 for i in range(56)] for i in range(len(key_table1)):
key0[i] = key[key_table1[i]-1] #生成16个密钥
for i in range(MaxTime):
key1 = [0 for i in range(48)]
#确定每次左移的步数
if (i == 0 or i == 1 or i == 8 or i == 15):
step = 1
else:
step = 2
#分成两组
tmp1 = key0[0:28]
tmp2 = key0[28:56]
#循环左移
tmp1 = Listmove(tmp1, step)
tmp2 = Listmove(tmp2, step)
#左右连接
key0 = tmp1 + tmp2
#置换选择
for i in range(len(key_table2)):
key1[i] = key0[key_table2[i]-1]
#生成密钥
keyresult.append(key1)
#返回的是一个集合包含了每次的密钥
return keyresult
F函数模块：
MaxTime = 16
#IP置换表
IP_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 ]
#逆IP置换表
Inv_IP_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 ]
#S盒中的S1盒
S1=[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 ]
#S盒中的S2盒
S2=[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 ]
#S盒中的S3盒
S3=[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 ]
#S盒中的S4盒
S4=[ 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 ]
#S盒中的S5盒
S5=[ 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 ]
#S盒中的S6盒
S6=[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 ]
#S盒中的S7盒
S7=[ 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]
#S盒中的S8盒
S8=[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 ]
# S盒
S=[S1,S2,S3,S4,S5,S6,S7,S8]
#用于对数据进行扩展置换，将32bit数据扩展为48bit
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 ]
#P盒
P_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 ] def int2bit(n):#0~15整数转比特
a=[]
for i in range(0,4):
a.insert(0,str(n%2))
n=int(n/2)
return a #IP置换部分，op为0表示正置换，op为1表示逆置换
def IP(text, op):
tmp = [0 for i in range(64)]
if op == 0:
for i in range(64):
tmp[i] = text[IP_table[i]-1]
return tmp
if op == 1:
for i in range(64):
tmp[i] = text[Inv_IP_table[i]-1]
return tmp
#进行扩展，将32位扩展为48位
def Extend(text):
extend = [0 for i in range(48)]
for i in range(48):
extend[i] = text[extend_table[i] - 1]
return extend #S盒变换部分
def S_replace(text):
Sresult = [0 for k in range(32)]
for k in range(8):
row = 2*int(text[k*6]) + int(text[k*6+5])
column = 8*int(text[k*6+1]) + 4*int(text[k*6+2]) + 2*int(text[k*6+3]) + int(text[k*6+4])
tmp = S[k][row*16+column] for i in range(4):
Sresult[4*k + i] = int2bit(tmp)[i]
return Sresult
#P置换部分
def P_replace(text):
Presult = [0 for i in range(32)]
for i in range(32):
Presult[i] = text[P_table[i]-1]
return Presult
#异或运算
def Xor(bit1, bit2):
Xorresult = [0 for i in range(len(bit1))]
for i in range(len(bit1)):
Xorresult[i] = str(int(bit1[i]) ^ int(bit2[i]))
return Xorresult
DES加密模块：
import CreateSubkey as cs
import F_function as f
#十六进制转二进制比特串
def Hex2bin(text):
result = []
for i in range(len(text)):
result.extend(f.int2bit(int(text[i],16)))
return result
#二进制比特串转十六进制
def bin2Hex(text):
result = []
q = len(text)//4
for i in range(q):
dec = int(text[4*i])*8 + int(text[4*i+1])*4 + int(text[4*i+2])*2 + int(text[4*i+3])*1
x = hex(dec)[2:].upper()
result.extend(x)
rs = ''.join(result)
return rs
#按照DES算法的流程图进行运算
def Encryption(text, key):
keylist = cs.Subkey(keybit)
text1 = f.IP(text, 0) #IP置换
L = [text1[i] for i in range(32)]
R = [text1[i] for i in range(32,64)]
for i in range(16):
tmp = R
tmp = f.Extend(tmp)
tmp = f.Xor(tmp, keylist[i])
tmp = f.S_replace(tmp)
tmp = f.P_replace(tmp)
tmp = f.Xor(tmp, L)
L = R
R = tmp
L,R = R,L
ctext = L
ctext.extend(R)
ctext = f.IP(ctext, 1)
return bin2Hex(ctext) if __name__ == '__main__':
plaintext = input('请输入用十六进制表示的明文：')
key = input('请输入用十六进制表示的密钥：')
ptext = Hex2bin(plaintext)
keybit = Hex2bin(key)
print('输出的密文为：' + Encryption(ptext, keybit))
DES解密模块：
import CreateSubkey as cs
import F_function as f
#十六进制转二进制比特串
def Hex2bin(text):
result = []
for i in range(len(text)):
result.extend(f.int2bit(int(text[i],16)))
return result
#二进制比特串转十六进制
def bin2Hex(text):
result = []
q = len(text)//4
for i in range(q):
dec = int(text[4*i])*8 + int(text[4*i+1])*4 + int(text[4*i+2])*2 + int(text[4*i+3])*1
x = hex(dec)[2:].upper()
result.extend(x)
rs = ''.join(result)
return rs def Encryption(text, key):
keylist = cs.Subkey(keybit)
text1 = f.IP(text, 0) #IP置换
L = [text1[i] for i in range(32)]
R = [text1[i] for i in range(32,64)]
for i in range(16):
tmp = R
tmp = f.Extend(tmp)
tmp = f.Xor(tmp, keylist[15-i])
tmp = f.S_replace(tmp)
tmp = f.P_replace(tmp)
tmp = f.Xor(tmp, L)
L = R
R = tmp
L,R = R,L
ctext = L
ctext.extend(R)
ctext = f.IP(ctext, 1)
return bin2Hex(ctext) if __name__ == '__main__':
plaintext = input('请输入用十六进制表示的密文：')
key = input('请输入用十六进制表示的密钥：')
ptext = Hex2bin(plaintext)
keybit = Hex2bin(key)
print('输出的明文为：' + Encryption(ptext, keybit))