DES加密算法详解.docx
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DES加密算法详解.docx
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DES加密算法详解
DES加密算法详解--
对加密解密一直挺喜欢的,可还是没有怎么好好学习过,希望这是一个好的开始。
在网上搜了一下关于DES的说明,发现有些杂乱,所以还是有必要整合一下。
写了一点代码,还没有完成,不过,还不能编译通过,^_^
刚看了一下,发现还是说得够模糊的,有机会再整理一下。
昏倒,一直运行不对,今天才仔细查出来,原来问题是出在Des_Data_P(const_b32&input,_b32output),
我的output用了传值调用,失败呀。
应该是Des_Data_P(const_b32&input,_b32&output)
DES算法的入口参数有三个:
Key,Data,Mode
Key为64bit密钥,Data为64bit数据,Mode为加密还是解密。
DES算法的过程:
1.对输入的密钥进行变换。
用户的64bit密钥,其中第8,16,24,32,40,48,56,64位是校验位,使得每个密钥都有奇数个1。
所以密钥事实上是56位。
对这56位密钥进行如下表的换位。
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,
表的意思是第57位移到第1位,第49位移到第2位,......以此类推。
变换后得到56bit数据,将它分成两部分,C[0][28],D[0][28]。
2.计算16个子密钥,计算方法C[i][28]D[i][28]为对前一个C[i-1][28],D[i-1][28]做循环左移操作。
16次的左移位数如下表:
1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,15,16 (第i次)
1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 (左移位数)
3.串联计算出来的C[i][28]D[i][28]得到56位,然后对它进行如下变换得到48位子密钥K[i][48]
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,
表的意思是第14位移到第1位,第17位移到第2位,以此类推。
在此过程中,发现第9,18,22,25,35,38,43,54位丢弃。
4.对64bit的明文输入进行换位变换。
换位表如下:
58,50,12,34,26,18,10, 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
表的意思就是第一次变换时,第58位移到第1位,第50位移到第2位,......依此类推。
得到64位数据,将这数据前后分成两块L[0][32],R[0][32]。
5.加密过程,对R[i][32]进行扩展变换成48位数,方法如下,记为E(R[i][32])
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,
6.将E(R[i][32])与K[i][48]作异或运算,得到48位数,将48位数顺序分成8份,6位一份,B[8][6]。
7.使用S[i]替换B[i][6]。
过程如下:
取出B[i][6]的第1位和第6位连成一个2位数m,m就是S[i]中对应的行数(0-3),取出B[i][6]的第2到第5位连成一个4位数n(0-15),n就是S[i]中对应的列数,用S[i][m][n]代替B[i][6]。
S是4行16列的对应表,里面是4位的数,一共有8个S,定义如下:
S[1]:
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[2]:
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[3]:
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[4]:
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[5]:
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[6]:
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[7]:
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[8]:
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,
8.将从B[i][6]经过S得到的8个4位数连起来得到32位数。
对这个数进行如下变换:
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,
得到的结果与L[i][32]作异或运算,把结果赋给R[i][32]。
9.把R[i-1][32]的值赋给L[i],从5开始循环。
直到K[16][48]结束。
10.将最后的L,R合并成64位,然后进行如下转化得到最后的结果。
这是对第4步的一个逆变化。
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
以上是Des的加密过程,解密过程同样,只需要把16个子密钥K[i][48]的顺序颠倒过来就行了。
对应于第1-3的key生成过程:
http:
//upload.wikimedia.org/wikipedia/en/thumb/3/3f/220px-DES-key-schedule.png
对应于第4步开始:
http:
//upload.wikimedia.org/wikipedia/en/thumb/f/fd/250px-DES-main-network.png
对应于第5步开始的循环操作:
http:
//upload.wikimedia.org/wikipedia/en/thumb/1/1b/270px-DES-f-function.png
代码:
/*filename:
gy_des.cpp
*/
/*
*Someofcodesarecopyedfromdes.libwhichiswrittenbyEricYoung(*************.au)
*Youcangetthelibfromftp:
//ftp.psy.uq.oz.au/pub/Crypto/DES/,
*/
#include"stdafx.h"
#include
#include
#include
#include
usingnamespacestd;
//usingnamespacegy;
typedefbitset<4>_b4;
typedefbitset<6>_b6;
typedefbitset<8>_b8;
typedefbitset<28>_b28;
typedefbitset<32>_b32;
typedefbitset<48>_b48;
typedefbitset<56>_b56;
typedefbitset<64>_b64;
typedefvector<_b8>_vb8;
typedefvector<_b48>_vb48;
typedefvector<_b64>_vb64;
namespace{
constunsignedcharodd_parity[256]={
1,1,2,2,4,4,7,7,8,8,11,11,13,13,14,14,
16,16,19,19,21,21,22,22,25,25,26,26,28,28,31,31,
32,32,35,35,37,37,38,38,41,41,42,42,44,44,47,47,
49,49,50,50,52,52,55,55,56,56,59,59,61,61,62,62,
64,64,67,67,69,69,70,70,73,73,74,74,76,76,79,79,
81,81,82,82,84,84,87,87,88,88,91,91,93,93,94,94,
97,97,98,98,100,100,103,103,104,104,107,107,109,109,110,110,
112,112,115,115,117,117,118,118,121,121,122,122,124,124,127,127,
128,128,131,131,133,133,134,134,137,137,138,138,140,140,143,143,
145,145,146,146,148,148,151,151,152,152,155,155,157,157,158,158,
161,161,162,162,164,164,167,167,168,168,171,171,173,173,174,174,
176,176,179,179,181,181,182,182,185,185,186,186,188,188,191,191,
193,193,194,194,196,196,199,199,200,200,203,203,205,205,206,206,
208,208,211,211,213,213,214,214,217,217,218,218,220,220,223,223,
224,224,227,227,229,229,230,230,233,233,234,234,236,236,239,239,
241,241,242,242,244,244,247,247,248,248,251,251,253,253,254,254
};
constintkeyperm_table56[56]={
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
};
constintkeycompperm_table[48]={
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
};
constintkeyshift_table[16]={
1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
};
constintdatainitperm_table[64]={
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
};
constintdataexpperm_table[48]={
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
};
constintdatasbox_table[8][4][16]={
{
{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},
}
};
constintdatapperm_table[32]={
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
};
constintdatafp_table[64]={
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,
36,4,44,12,52,20,60,28,3
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