DES加密运算步骤
- 输入64位明文数据，并进行初始置换IP；
- 在初始置换IP后，明文数据再被分为左右两部分，每部分32位，以L0，R0表示；
- 在秘钥的控制下，经过16轮运算(f)；
- 16轮后，左、右两部分交换，并连接再一起，再进行逆置换；
- 输出64位密文。
初始置换
这里要使用IP置换表。
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,
这里的意思是将输入的64位明文按照表排列，即第58位明文排在第一位，第50位明文排在第二位，依次类推获得一个新的64位的串
密钥生成器
密钥移位表
64位密钥压缩为56位表
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
56位密钥压缩为48位表
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
将这个56位表分成前28位和后28位，即C0和D0表
又将64位密钥按照C0和D0表置换成28位L0和28位R0(置换规则和前面一样)
将L0和R0按照加密轮数进行移位。(tips:每次移位是接着上次已经移位后的串继续移位)
将L0和R0拼接为一个56位的串key_56。
将key_56按照48位表置换得到key_48(置换规则和ip置换一样)
这里已经获得了一个key，按照移位表进行循环一共得到16个key。
密钥生成流程图
E/p扩展
新一轮加密的开始
第一轮使用I/P置换得到的64位串，下一轮使用P置换得到的64位串。
将得到的64位串分成两部分，前32位为左L0，后32位右R0。
将右32位进行E/P扩展变成48位。
E/P扩展置换表
置换规则和ip置换一样
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
E/P结束后我们得到了一个48位的串R1
R1与key异或
将R1与key进行异或运算得到新的R1
tmp+=bin(int(r1,2)^int(keys[i],2))[2:] #R1和key对应异或
while len(tmp)<48:
tmp='0'+tmp
return tmp
S盒置换
有8个S盒置换表（太多这里先不写出来放在后面代码中）
流程如图，将上一步异或得到的R1每6位分为一组，共计8组。
每组6位，将高一位和低一位组合形成行，中间4位作为列进行S盒置换。
例如
111001 那么对应11就是行，1100就是列。
每组我们能够获得4位的串，一共8组，将8组数进行拼接得到32位的新的R1串。
P置换
P置换表
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,
将S盒置换后得到的32位R1进行P置换得到新的32位R1 (置换规则和IP置换一样)
这里将前面E/P置换得到的L0和这个R1进行异或运算得到新的R1
令L1＝E/P置换得到的R0。
将L1和R1组合得到一个新的64位串
到这儿，我们已经进行了一轮加密。后面将这64位串传给E/P置换，进行下一轮。
IP逆置换
IP逆置换表
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,
经过前面16轮加密，我们得到了一个64位串。
但是我们每一轮结束有一个L1和R1交换的操作，最后一轮结束是不需要L1和R1交换
所以我们将这个64位串分割成左32位和右32位，然后左右交换组合新的64位串
将这个64位串进行ip逆置换，得到加密结果（置换规则和IP置换规则一样）
解密
解密就是将第16位key作为第一位key，第15位作为第二位key，依次类推。得到一个逆序的key，进行加密就ok。
因为解密是加密的一个逆过程。
DES流程图
代码
#data='1001100001110110010101000011001000010001010001110010010110000011'
#secret_key='0001001000110100010101100111100010010001001000110100010101100111'
#加密结果 0111110010101110111011000000001001001010111000011010110111001011
#加密结果 0x7caeec024ae1adcb
#ip置换表
ip=[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]
#ip逆置换表
ip_=[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
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 ] ]
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 ] ]
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 ] ]
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 ] ]
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 ] ]
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 ] ]
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 ] ]
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 ] ]
# p置换表
p=[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]
#压缩密钥到56位
cre_56key=[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]
#压缩密钥到48位
cre_48key=[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]
#左移动次数
mobile_n=[1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1]
#轮密钥
keys=[]
#E扩展矩阵
E= [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]
#ip置换
def ip_replace(tem_data):
c=[]
for i in ip:
c.append(tem_data[i-1])
return c
#E/P扩展
def Extension(r0):
r1=[]
for i in E:
r1.append(str(r0[i-1]))
return r1
#轮密钥生成
def cre_keys(secret_key):
temp=[]
for i in cre_56key:
temp.append(secret_key[i-1])
c0=cre_56key[0:28]
d0=cre_56key[28:]
L0=[]
R0=[]
for i in c0:
L0.append(secret_key[i-1])
for i in d0:
R0.append(secret_key[i-1])
for i in range(16):
L0=L0[mobile_n[i]:]+L0[0:mobile_n[i]]
R0=R0[mobile_n[i]:]+R0[0:mobile_n[i]]
temp_k=L0+R0
key1=[]
for i in cre_48key:
key1.append(str(temp_k[i-1]))
keys.append("".join(key1))
#S盒替换
def s_replace(r1):
s_box=['s1[r][c]','s2[r][c]','s3[r][c]','s4[r][c]','s5[r][c]','s6[r][c]','s7[r][c]','s8[r][c]']
s_dates=""
for i in range(8):
if i!=7:
s_data=r1[i*6:(i+1)*6]
else:
s_data=r1[i*6:]
r=int(s_data[0]+s_data[-1],2)
c=int(s_data[1:-1],2)
s_da=bin(eval(s_box[i]))[2:]
patter=4-len(s_da)
s_da='0'*patter+s_da
s_dates+=s_da
return s_dates
#P置换
def P_replace(l0,s_dates,old_r0):
temp_r=''
temp_l=''
temp=''
for i in p:
temp_r+=s_dates[i-1]
for i in l0:
temp_l+=str(i)
temp=bin(int(temp_l,2)^int(temp_r,2))[2:]
while len(temp)<32:
temp='0'+temp
r1=[]
l1=old_r0
for i in temp:
r1.append(int(i))
temp_data=l1+r1
return temp_data
#ip逆置换
def _ip_replace(temp_data):
data=temp_data[32:]+temp_data[0:32]
cipher=[]
for i in ip_:
cipher.append(data[i-1])
return cipher
if __name__ == "__main__":
#data=input('输入data:')
#secret_key=input('输入密钥:')
data='1001100001110110010101000011001000010001010001110010010110000011'
secret_key='0001001000110100010101100111100010010001001000110100010101100111'
tem_data=[]
cre_keys(secret_key)
for i in range(len(data)):
if i==" ":
continue
tem_data.append(int(data[i]))
c=ip_replace(tem_data)
for i in range(16):
l0=c[0:32]
r0=c[32:]
r1=Extension(r0)
r1="".join(r1)
tmp=""
tmp+=bin(int(r1,2)^int(keys[i],2))[2:]
while len(tmp)<48:
tmp='0'+tmp
s_dates=s_replace(tmp)
c=P_replace(l0,s_dates,r0)
cipher=_ip_replace(c)
secret=''
for i in cipher:
secret+=str(i)
print('DES加密结果:',secret)
print('DES加密结果:',hex(int(secret,2)))