浅析一个DES源码(WjcDes.cpp)的错误以及测试的重要性
偶很久没有来论坛了,也没有玩关于密码学方面的东西了，主要感觉自己数学知识薄弱，并
不是研究此类问题的料子，况且现在满世界是现成的东西，只要有人指点一下就可以抓来
进行应用，自力更生反而是不重要的东西了。:(
前一阵子，因为需要，重新翻开书本，并对照FIPS46-3，自己写了DES的实现，以前Lordor教我
的时候我没有好好儿学，现在比较吃力:)经过反复抓虫，通过了一些测试证实了代码的正确性。
同时，由于程序员的通病:总要将自己的代码和
别人写的做比较（一是比比速度，二是比比哪个代码质量高容易使用，并且借此机会学习别人
的长处），所以找到了一些DES的实现拿来编译。
其中由王俊川编写的代码引起了我的注意，因为他的代码简练有条理，并且通过ByteToBit扩展，
将bit级别的问题简化成byte级别的操作，而且很容易在VC上面编译。
他的代码在VC知识库(www.vckbase.net)上可以被下载到:
100行的版本: http://www.vckbase.net/code/downcode.asp?id=1897
80行的版本: http://www.vckbase.net/code/downcode.asp?id=1889
实际上二者的核心是一样的，用任何一个都可以的。
以下测试平台为windows xp + MSVC 6.0 +sp5
以下引用为WjcDes.cpp.
//////////////////////////////////////////////////////////////////////////
/*
Provided by 王俊川, Northeastern University ([url]www.neu.edu.cn[/url])
Email: [email]blackdrn@sohu.com[/email]
This product is free for use.
*/
//////////////////////////////////////////////////////////////////////////
#include "memory.h"
#include "WjcDes.h"
//////////////////////////////////////////////////////////////////////////
static void F_func(bool In[32], const bool Ki[48]);// f 函数
static void S_func(bool Out[32], const bool In[48]);// S 盒代替
static void Transform(bool *Out, bool *In, const char *Table, int len);// 变换
static void Xor(bool *InA, const bool *InB, int len);// 异或
static void RotateL(bool *In, int len, int loop);// 循环左移
static void ByteToBit(bool *Out, const char *In, int bits);// 字节组转换成位组
static void BitToByte(char *Out, const bool *In, int bits);// 位组转换成字节组
//////////////////////////////////////////////////////////////////////////
// initial permutation IP
const static char IP_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
};
// final permutation IP^-1
const static char IPR_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
};
// expansion operation matrix
static const char E_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
};
// 32-bit permutation function P used on the output of the S-boxes
const static char P_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
};
// permuted choice table (key)
const static char PC1_Table[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
};
// permuted choice key (table)
const static char PC2_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
};
// number left rotations of pc1
const static char LOOP_Table[16] = {
1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
};
// The (in)famous S-boxes
const static char S_Box[8][4][16] = {
// 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
};
//////////////////////////////////////////////////////////////////////////
static bool SubKey[16][48];// 16圈子密钥
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
// Code starts from Line 121
//////////////////////////////////////////////////////////////////////////
void Des_Run(char Out[8], char In[8], bool Type)
{
static bool M[64], Tmp[32], *Li = &M[0], *Ri = &M[32];
ByteToBit(M, In, 64);
Transform(M, M, IP_Table, 64);
if( Type == ENCRYPT ){
for(int i=0; i<16; i++) {
memcpy(Tmp, Ri, 32);
F_func(Ri, SubKey[i]);
Xor(Ri, Li, 32);
memcpy(Li, Tmp, 32);
}
}else{
for(int i=15; i>=0; i--) {
memcpy(Tmp, Li, 32);
F_func(Li, SubKey[i]);
Xor(Li, Ri, 32);
memcpy(Ri, Tmp, 32);
}
}
Transform(M, M, IPR_Table, 64);
BitToByte(Out, M, 64);
}
void Des_SetKey(const char Key[8])
{
static bool K[64], *KL = &K[0], *KR = &K[28];
ByteToBit(K, Key, 64);
Transform(K, K, PC1_Table, 56);
for(int i=0; i<16; i++) {
RotateL(KL, 28, LOOP_Table[i]);
RotateL(KR, 28, LOOP_Table[i]);
Transform(SubKey[i], K, PC2_Table, 48);
}
}
void F_func(bool In[32], const bool Ki[48])
{
static bool MR[48];
Transform(MR, In, E_Table, 48);
Xor(MR, Ki, 48);
S_func(In, MR);
Transform(In, In, P_Table, 32);
}
void S_func(bool Out[32], const bool In[48])
{
for(char i=0,j,k; i<8; i++,In+=6,Out+=4) {
j = (In[0]<<1) + In[5];
k = (In[1]<<3) + (In[2]<<2) + (In[3]<<1) + In[4];
ByteToBit(Out, &S_Box[i][j][k], 4);
}
}
void Transform(bool *Out, bool *In, const char *Table, int len)
{
static bool Tmp[256];
for(int i=0; i<len; i++)
Tmp[i] = In[ Table[i]-1 ];
memcpy(Out, Tmp, len);
}
void Xor(bool *InA, const bool *InB, int len)
{
for(int i=0; i<len; i++)
InA[i] ^= InB[i];
}
void RotateL(bool *In, int len, int loop)
{
static bool Tmp[256];
memcpy(Tmp, In, loop);
memcpy(In, In+loop, len-loop);
memcpy(In+len-loop, Tmp, loop);
}
void ByteToBit(bool *Out, const char *In, int bits)
{
for(int i=0; i<bits; i++)
Out[i] = (In[i/8]>>(i%8)) & 1;
}
void BitToByte(char *Out, const bool *In, int bits)
{
memset(Out, 0, (bits+7)/8);
for(int i=0; i<bits; i++)
Out[i/8] |= In[i]<<(i%8);
}
//////////////////////////////////////////////////////////////////////////
// Code ends at Line 200
//////////////////////////////////////////////////////////////////////////
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