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, _b32 output),
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
*/
/*
* Someof codes are copyed from des.lib which is written by Eric Young(eay@mincom.oz.au)
* Youcan get the lib from ftp://ftp.psy.uq.oz.au/pub/Crypto/DES/,
*/
#include"stdafx.h"
#include< bitset >
#include< vector >
#include< string >
#include< iostream >
usingnamespace std;
//usingnamespace gy;
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{
const unsigned char odd_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
};
const int keyperm_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
};
const int keycompperm_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
};
const int keyshift_table[16] = {
1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2,2, 2, 2, 2, 1
};
const int datainitperm_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
};
const int dataexpperm_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
};
const int datasbox_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},
}
};
const int datapperm_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
};
const int datafp_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, 28,35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,33, 1, 41, 9, 49, 17, 57, 25
};
template < size_t _NB >
void rotateleft_bitset(bitset< _NB>& input, size_t step)
{
bitset< _NB > tmp = input;
input <<= step;
tmp >>= _NB - step;
input |= tmp;
}
template < size_t _NB >
void rotateright_bitset(bitset<_NB >& input, size_t step)
{
bitset< _NB > tmp = input;
input >>= step;
tmp <<= _NB - step;
input |= tmp;
}
template < class Input, class Output,class Table>
void Des_Permutation( const Input&input, Output& output, const Table& table, size_t TableSize)
{
for (size_t i = 0; i <TableSize; ++i) {
output[i] = input[table[i]-1 ];
}
}
void Des_Key_Permutation1(const_b64& input, _b56& output)
{
Des_Permutation(input, output,keyperm_table56, sizeof(keyperm_table56)/sizeof(int));
}
void Des_Key_CompPerm(const _b56&input, _b48& output)
{
Des_Permutation(input, output,keycompperm_table, sizeof(keycompperm_table)/sizeof(int));
}
void Des_Key_Shift(_b56& key56,size_t step)
{
_b28 l28, r28;
int i;
for (i = 0; i < 28; ++i) {
r28[i] = key56[i];
l28[i] = key56[28+i];
}
rotateleft_bitset(l28, step);
rotateleft_bitset(r28, step);
for (i = 0; i < 28; ++i) {
key56[i] = r28[i];
key56[28+i] = l28[i];
}
}
void Des_Key_Generate(const _b64&key, _vb48& subkey)
{
_b56 tmp56;
Des_Key_Permutation1(key, tmp56);
for (int i = 0; i < 16; ++i) {
_b48 tmp48;
Des_Key_Shift(tmp56,keyshift_table[i]);
Des_Key_CompPerm(tmp56,tmp48);
cout << "Key:" << tmp48 << endl;
subkey.push_back(tmp48);
}
}
void Des_Char_To_Binary(char c,string& binary)
{
unsigned char tmp =odd_parity[c];
binary.append( (tmp & 0x80) ?"1" : "0" );
binary.append( (tmp & 0x40) ?"1" : "0" );
binary.append( (tmp & 0x20) ?"1" : "0" );
binary.append( (tmp & 0x10) ?"1" : "0" );
binary.append( (tmp & 0x08) ?"1" : "0" );
binary.append( (tmp & 0x04) ?"1" : "0" );
binary.append( (tmp & 0x02) ?"1" : "0" );
binary.append( (tmp & 0x01) ?"1" : "0" );
}
void Des_String_To_Binary(conststring& input, _b64& output)
{
string binary;
for (int i = 0; i <input.length(); ++i ) {
Des_Char_To_Binary(input[i],binary);
}
_b64 tmp64(binary);
output = tmp64;
}
void Des_String_To_Key(const string&key, _vb48& subkey)
{
_b64 tmp64;
Des_String_To_Binary(key, tmp64);
Des_Key_Generate(tmp64, subkey);
}
void Des_Data_ExpPerm(const _b32&input, _b48& output)
{
Des_Permutation(input, output,dataexpperm_table, sizeof(dataexpperm_table)/sizeof(int));
}
void Des_Data_IP(const _b64& input,_b64& output)
{
Des_Permutation(input, output,datainitperm_table, sizeof(datainitperm_table)/sizeof(int));
}
void Des_Data_S(const _b6& input,_b4& output, int step)
{
bitset< 2 > tmp2;
_b4 tmp4;
tmp2[0] = input[5];
tmp2[1] = input[0];
tmp4[0] = input[1];
tmp4[1] = input[2];
tmp4[2] = input[3];
tmp4[3] = input[4];
_b8t8(datasbox_table[step][tmp2.to_ulong()][tmp4.to_ulong()]);
for (int i = 0; i < 4; ++i) {
output[i] = t8[i];
}
}
void Des_Data_S(const _b48& input,_b32& output)
{
_b6 tmp6;
_b4 tmp4;
int i, j;
for (i = 0; i < 8; ++i) {
for (j = 6; j < 0;--j) {
tmp6[j] = input[47 - i*6 - j];
}
Des_Data_S(tmp6, tmp4,i);
for (j = 0; j < 4;++j) {
output[ 31 - (i<< 2) - j] = tmp4[j];
}
}
}
void Des_Data_P(const _b32& input,_b32& output)
{
Des_Permutation(input, output,datapperm_table, sizeof(datapperm_table)/sizeof(int));
}
void Des_Data_F(_b64& input, const_b48& key)
{
_b32 l32, r32, tmp32, t32;
_b48 exp48;
int i;
for (i = 0; i < 32; ++i ) {
r32[i] = input[i];
l32[i] = input[32+i];
}
//cout << "r32**" << r32 << endl;
Des_Data_ExpPerm(r32, exp48);
//cout << "exp**" << exp48 << endl;
//cout << "key**" << key << endl;
exp48 ^= key;
//cout << "exp**" << exp48 << endl;
Des_Data_S(exp48, tmp32);
//cout << "tmp**" << tmp32 << endl;
Des_Data_P(tmp32, t32);
//cout << "t32**" << t32 << endl;
t32 ^= l32;
l32 = r32;
r32 = t32;
for (i = 0; i < 32; ++i ) {
input[i] = r32[i];
input[32+i] = l32[i];
}
}
void Des_data_FP(const _b64& input,_b64& output)
{
Des_Permutation(input, output,datafp_table, sizeof(datafp_table)/sizeof(int));
}
int Des_encode_64bit(const _vb48&key, const _b64 &data, _b64 &output)
{
_b64 tmp64;
Des_Data_IP(data, tmp64);
for (int i = 0; i < 16; ++i) {
//cout << " " << tmp64 << endl;
Des_Data_F(tmp64,key[i]);
//cout << " " << tmp64 << endl;
}
Des_data_FP(tmp64, output);
return 0;
}
int Des_encode(const string& key,const string& data, _b64 &output)
{
_vb48 subkey, decodekey;
_b64 data64, tmp64;
Des_String_To_Key(key, subkey);
for (int i = 0; i < 16; ++i) {
decodekey.push_back(subkey[15-i ]);
}
Des_String_To_Binary(data,data64);
//cout << "data: " << data64 << endl;
Des_encode_64bit(subkey, data64,output);
//cout << "code: " << output << endl;
Des_encode_64bit(decodekey,output, tmp64);
//cout << "reco: " << tmp64 << endl;
if (tmp64 == data64) {
cout <<"Congratulation.$$$$$$$$$$$$$$$$$$$$$$$" << endl;
}else {
cout <<"Error. **************************" << endl;
}
return 0;
}
int Des_decode(const string& key,const string& data, _b64 &output)
{
return 0;
}
}
namespacegy {
/* Mode: true for encode, false fordecode */
int Des(const string& key, conststring& data, _b64 &output, bool Mode)
{
if (Mode) {
return Des_encode(key,data, output);
}else {
return Des_decode(key,data, output);
}
}
void Run_Des(void)
{
int select = 0;
string data, key;
cout << "1.encode;" << endl << "2. decode;" << endl<< "Your choise: ";
cin >> select;
cout << endl <<"Please input the data: ";
cin >> data;
cout << endl <<"Please input the key: ";
cin >> key;
_b64 output;
if (select == 1) {
Des(key, data, output,true);
}else {
Des(key, data, output,false);
}
}
}
原文：http://blog.csdn.net/u014316433/article/details/26342377