胖子's Blog
慢慢的走
DES 算法 C51 单片机
顶顶大名的DES算法大家都知道吧，呵呵！这里就不用多做介绍了，关于它的c源码，网上一搜一大把，虽然很多是不正确的实现，但是也有正确的，比如：http://www.cnblogs.com/erwin/archive/2009/04/14/1435288.html这位达人的算法实现个人认为还是不错的，至少它的加密结果是正确的，而且结构相当清晰，虽然还有点小bug（可以看这篇日志下面的评论），但是胖子认为自己是写不出这么好的程序（DES太可怕啦
）！如果说有童鞋怀疑其加密结果的正确性，或者想验证一下自己写的DES程序的结果是否正确，胖子在这里提供一个比较权威的工具，你到中文wiki上找到DES的介绍页面，页面下方有个链接，是一个DES的实现，当然是用的javascript，不过它限制了密钥的不能更改，你可以保存页面后，把那个textbox的属性改一下就可以验证了。只输入第一个密钥，则加密算法就是DES（http://people.eku.edu/styere/Encrypt/JS-DES.html）。
好了，废话不多说了，该进入今天的主题了。就是C51单片机上DES算法的实现。众所周知，51单片机的ram很小，胖子用的这个ram+flash才512byte，这对于DES的实现提出了非常苛刻的要求。胖子自问没有时间搞这个，所以就求助谷歌与百度大叔，花费了n久，历经n次劫难，最终取得真经。以下就是程序源码：
#include <string.h>
#include <stdlib.h>
#include <reg52.h>
static unsigned char code DesIp[] =
{
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
};
static unsigned char code DesIp_1[] =
{
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
};
static unsigned char code DesS[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}
}
};
static unsigned char code DesE[] =
{
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
};
static unsigned char code DesP[] =
{
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
};
static unsigned char code DesPc_1[] =
{
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
};
static unsigned char code DesPc_2[] =
{
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
};
static unsigned char code DesRots[] =
{
1, 1, 2, 2,
2, 2, 2, 2,
1, 2, 2, 2,
2, 2, 2, 1,
0
};
static void movram(unsigned char* source,unsigned char* target,unsigned char length);
static void doxor(unsigned char* sourceaddr,unsigned char* targetaddr,unsigned char length);
static void setbit(unsigned char* dataddr,unsigned char pos,unsigned char b0);
static unsigned char getbit(unsigned char* dataddr,unsigned char pos);
static void selectbits(unsigned char* source,unsigned char* table,unsigned char* target,unsigned char count);
static void shlc(unsigned char* data_p);
static void shrc(unsigned char* data_p);
static void strans(unsigned char* index,unsigned char* target);
static void movram(unsigned char* source,unsigned char* target,unsigned char length)
{
unsigned char i;
for(i = 0;i < length;i++)/*?????*/
{
target[i] = source[i];
}
}
static void doxor(unsigned char* sourceaddr,unsigned char* targetaddr,unsigned char length)
{
unsigned char i;
for (i = 0;i < length;i++)/*???*/
{
sourceaddr[i] ^= targetaddr[i];
}
}
static void setbit(unsigned char* dataddr,unsigned char pos,unsigned char b0)
{
unsigned char byte_count;
unsigned char bit_count;
unsigned char temp;
temp = 1;
byte_count = (pos - 1) / 8;
bit_count = 7 - ((pos - 1) % 8);
temp <<= bit_count;
if(b0)
{
dataddr[byte_count] |= temp;
}
else
{
temp = ~temp;
dataddr[byte_count] &= temp;
}
}
static unsigned char getbit(unsigned char* dataddr,unsigned char pos)
{
unsigned char byte_count;
unsigned char bit_count;
unsigned char temp;
temp = 1;
byte_count = (pos - 1) / 8;
bit_count = 7 - ((pos - 1) % 8);
temp <<= bit_count;
if(dataddr[byte_count] & temp)
{
return(1);
}
else
{
return(0);
}
}
static void selectbits(unsigned char* source,unsigned char* table,unsigned char* target,unsigned char count)
{
unsigned char i;
for(i = 0;i < count;i++)
{
setbit(target,i + 1,getbit(source,table[i]));
}
}
static void shlc(unsigned char* data_p)
{
unsigned char i,b0;
b0 = getbit(data_p,1);
for(i = 0;i < 7;i++)
{
data_p[i] <<= 1;
if(i != 6)
{
setbit(&data_p[i],8,getbit(&data_p[i + 1],1));
}
}
setbit(data_p,56,getbit(data_p,28));
setbit(data_p,28,b0);
}
static void shrc(unsigned char* data_p)
{
unsigned char b0;
int i;
b0 = getbit(data_p,56);
for(i = 6;i >= 0;i--)
{
data_p[i] >>= 1;
if(i != 0)
{
setbit(&data_p[i],1,getbit(&data_p[i - 1],8));
}
}
setbit(data_p,1,getbit(data_p,29));
setbit(data_p,29,b0);
}
/* The problem is about yielded in this function */
static void strans(unsigned char* index,unsigned char* target)
{
unsigned char row,line,t,i,j,b0,b1;
for(i = 0;i < 4;i++)
{
row = line = t = 0;
setbit(&line,7,b0 = getbit(index,i * 12 + 1));
setbit(&line,8,b1 = getbit(index,i * 12 + 6));
for(j = 2;j < 6;j++)
{
setbit(&row,3 + j,getbit(index,i * 12 + j));
}
t = DesS[i * 2][line][row];
t <<= 4;
line = row = 0;
setbit(&line,7,getbit(index,i * 12 + 7));
setbit(&line,8,getbit(index,i * 12 + 12));
for(j = 2;j < 6;j++)
{
setbit(&row,3 + j,getbit(index,i * 12 + 6 + j));
}
t |= DesS[i * 2 + 1][line][row];
target[i] = t;
}
}
void des(unsigned char *data_p,unsigned char* key_p,int type)
{
unsigned char tempbuf[12];
unsigned char key[7];
unsigned char i;
unsigned char j;
unsigned char count;
void (*f)(unsigned char* data_p);
selectbits(data_p,DesIp,tempbuf,64);/*????*/
movram(tempbuf,data_p,8);
selectbits(key_p,DesPc_1,key,56);/*KEY?????*/
for(i = 0;i < 16;i ++)
{
selectbits(data_p + 4,DesE,tempbuf,48);/*????*/
if(type ==1) //jia mi
{
f = shlc;
count = i;
}
else
{
count = 16 - i;
f = shrc;
}
for(j = 0;j < DesRots[count];j++)/*KEY ???*/
{
f(key);
}
selectbits(key,DesPc_2,tempbuf + 6,48);/*KEY ????*/
doxor(tempbuf,tempbuf + 6,6);
strans(tempbuf,tempbuf + 6);
selectbits(tempbuf + 6,DesP,tempbuf,32);
doxor(tempbuf,data_p,4);
if(i < 15)
{
movram(data_p + 4,data_p,4);
movram(tempbuf,data_p + 4,4);
}
}
movram(tempbuf,data_p,4);
selectbits(data_p,DesIp_1,tempbuf,64);
movram(tempbuf,data_p,8);
}
void main(void)
{
unsigned char key[8] = {'c','o','m','p','u','t','e','r'
unsigned char text[8]={'l','e','a','r','n','i','n','g'};
des(text,key,1);
}
在这里胖子只能说是付出了上网和测试的功劳，至于编码的功劳不敢冒领，可惜不知道作者是谁，在这里向这位达人致敬了
~，在这里希望各位需要在单片机上跑DES的各位童鞋，少走点弯路，欢迎转载，当然请注明出处，哈哈~