DES算法.docx
- 文档编号:26749694
- 上传时间:2023-06-22
- 格式:DOCX
- 页数:17
- 大小:20.42KB
DES算法.docx
《DES算法.docx》由会员分享,可在线阅读,更多相关《DES算法.docx(17页珍藏版)》请在冰豆网上搜索。
DES算法
DES算法把64位的明文输入块变为64位的密文输出块,它所使用的密钥也是64位,整个算法的主流程图如下:
其功能是把输入的64位数据块按位重新组合,并把输出分为L0、R0两部分,每部分各长32位,其置换规则见下表:
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,
即将输入的第58位换到第一位,第50位换到第2位,...,依此类推,最后一位是原来的第7位。
L0、R0则是换位输出后的两部分,L0是输出的左32位,R0是右32位,例:
设置换前的输入值为D1D2D3......D64,则经过初始置换后的结果为:
L0=D58D50...D8;R0=D57D49...D7。
经过16次迭代运算后。
得到L16、R16,将此作为输入,进行逆置换,即得到密文输出。
逆置换正好是初始置的逆运算,例如,第1位经过初始置换后,处于第40位,而通过逆置换,又将第40位换回到第1位,其逆置换规则如下表所示:
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,
34,2,42,10,50,18,5826,33,1,41,9,49,17,57,25,
放大换位表
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,
单纯换位表
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,
在f(Ri,Ki)算法描述图中,S1,S2...S8为选择函数,其功能是把6bit数据变为4bit数据。
下面给出选择函数Si(i=1,2......8)的功能表:
选择函数Si
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,
在此以S1为例说明其功能,我们可以看到:
在S1中,共有4行数据,命名为0,1、2、3行;每行有16列,命名为0、1、2、3,......,14、15列。
现设输入为:
D=D1D2D3D4D5D6
令:
列=D2D3D4D5
行=D1D6
然后在S1表中查得对应的数,以4位二进制表示,此即为选择函数S1的输出。
下面给出子密钥Ki(48bit)的生成算法
从子密钥Ki的生成算法描述图中我们可以看到:
初始Key值为64位,但DES算法规定,其中第8、16、......64位是奇偶校验位,不参与DES运算。
故Key实际可用位数便只有56位。
即:
经过缩小选择换位表1的变换后,Key的位数由64位变成了56位,此56位分为C0、D0两部分,各28位,然后分别进行第1次循环左移,得到C1、D1,将C1(28位)、D1(28位)合并得到56位,再经过缩小选择换位2,从而便得到了密钥K0(48位)。
依此类推,便可得到K1、K2、......、K15,不过需要注意的是,16次循环左移对应的左移位数要依据下述规则进行:
循环左移位数
1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
以上介绍了DES算法的加密过程。
DES算法的解密过程是一样的,区别仅仅在于第一次迭代时用子密钥K15,第二次K14、......,最后一次用K0,算法本身并没有任何变化。
DES算法网络上很多,给你们一个
/*================================================================
des()
Description:
DESalgorithm,doencriptordescript.
================================================================*/
intdes(unsignedchar*source,unsignedchar*dest,unsignedchar*inkey,intflg)
{
unsignedcharbufout[64],
kwork[56],worka[48],kn[48],buffer[64],key[64],
nbrofshift,temp1,temp2;
intvalindex;
registeri,j,k,iter;
/*INITIALIZETHETABLES*/
/*Table-s1*/
staticunsignedchars1[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};
/*Table-s2*/
staticunsignedchars2[4][16]={
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};
/*Table-s3*/
staticunsignedchars3[4][16]={
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};
/*Table-s4*/
staticunsignedchars4[4][16]={
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};
/*Table-s5*/
staticunsignedchars5[4][16]={
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};
/*Table-s6*/
staticunsignedchars6[4][16]={
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};
/*Table-s7*/
staticunsignedchars7[4][16]={
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};
/*Table-s8*/
staticunsignedchars8[4][16]={
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};
/*Table-Shift*/
staticunsignedcharshift[16]={
1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
/*Table-Binary*/
staticunsignedcharbinary[64]={
0,0,0,0,0,0,0,1,0,0,1,0,0,0,1,1,
0,1,0,0,0,1,0,1,0,1,1,0,0,1,1,1,
1,0,0,0,1,0,0,1,1,0,1,0,1,0,1,1,
1,1,0,0,1,1,0,1,1,1,1,0,1,1,1,1};
/*MAINPROCESS*/
/*Convertfrom64-bitkeyinto64-bytekey*/
for(i=0;i<8;i++){
key[8*i]=((j=*(inkey+i))/128)%2;
key[8*i+1]=(j/64)%2;
key[8*i+2]=(j/32)%2;
key[8*i+3]=(j/16)%2;
key[8*i+4]=(j/8)%2;
key[8*i+5]=(j/4)%2;
key[8*i+6]=(j/2)%2;
key[8*i+7]=j%2;
}
/*Convertfrom64-bitdatainto64-bytedata*/
for(i=0;i<8;i++){
buffer[8*i]=((j=*(source+i))/128)%2;
buffer[8*i+1]=(j/64)%2;
buffer[8*i+2]=(j/32)%2;
buffer[8*i+3]=(j/16)%2;
buffer[8*i+4]=(j/8)%2;
buffer[8*i+5]=(j/4)%2;
buffer[8*i+6]=(j/2)%2;
buffer[8*i+7]=j%2;
}
/*InitialPermutationofData*/
bufout[0]=buffer[57];
bufout[1]=buffer[49];
bufout[2]=buffer[41];
bufout[3]=buffer[33];
bufout[4]=buffer[25];
bufout[5]=buffer[17];
bufout[6]=buffer[9];
bufout[7]=buffer[1];
bufout[8]=buffer[59];
bufout[9]=buffer[51];
bufout[10]=buffer[43];
bufout[11]=buffer[35];
bufout[12]=buffer[27];
bufout[13]=buffer[19];
bufout[14]=buffer[11];
bufout[15]=buffer[3];
bufout[16]=buffer[61];
bufout[17]=buffer[53];
bufout[18]=buffer[45];
bufout[19]=buffer[37];
bufout[20]=buffer[29];
bufout[21]=buffer[21];
bufout[22]=buffer[13];
bufout[23]=buffer[5];
bufout[24]=buffer[63];
bufout[25]=buffer[55];
bufout[26]=buffer[47];
bufout[27]=buffer[39];
bufout[28]=buffer[31];
bufout[29]=buffer[23];
bufout[30]=buffer[15];
bufout[31]=buffer[7];
bufout[32]=buffer[56];
bufout[33]=buffer[48];
bufout[34]=buffer[40];
bufout[35]=buffer[32];
bufout[36]=buffer[24];
bufout[37]=buffer[16];
bufout[38]=buffer[8];
bufout[39]=buffer[0];
bufout[40]=buffer[58];
bufout[41]=buffer[50];
bufout[42]=buffer[42];
bufout[43]=buffer[34];
bufout[44]=buffer[26];
bufout[45]=buffer[18];
bufout[46]=buffer[10];
bufout[47]=buffer[2];
bufout[48]=buffer[60];
bufout[49]=buffer[52];
bufout[50]=buffer[44];
bufout[51]=buffer[36];
bufout[52]=buffer[28];
bufout[53]=buffer[20];
bufout[54]=buffer[12];
bufout[55]=buffer[4];
bufout[56]=buffer[62];
bufout[57]=buffer[54];
bufout[58]=buffer[46];
bufout[59]=buffer[38];
bufout[60]=buffer[30];
bufout[61]=buffer[22];
bufout[62]=buffer[14];
bufout[63]=buffer[6];
/*InitialPermutationofKey*/
kwork[0]=key[56];
kwork[1]=key[48];
kwork[2]=key[40];
kwork[3]=key[32];
kwork[4]=key[24];
kwork[5]=key[16];
kwork[6]=key[8];
kwork[7]=key[0];
kwork[8]=key[57];
kwork[9]=key[49];
kwork[10]=key[41];
kwork[11]=key[33];
kwork[12]=key[25];
kwork[13]=key[17];
kwork[14]=key[9];
kwork[15]=key[1];
kwork[16]=key[58];
kwork[17]=key[50];
kwork[18]=key[42];
kwork[19]=key[34];
kwork[20]=key[26];
kwork[21]=key[18];
kwork[22]=key[10];
kwork[23]=key[2];
kwork[24]=key[59];
kwork[25]=key[51];
kwork[26]=key[43];
kwork[27]=key[35];
kwork[28]=key[62];
kwork[29]=key[54];
kwork[30]=key[46];
kwork[31]=key[38];
kwork[32]=key[30];
kwork[33]=key[22];
kwork[34]=key[14];
kwork[35]=key[6];
kwork[36]=key[61];
kwork[37]=key[53];
kwork[38]=key[45];
kwork[39]=key[37];
kwork[40]=key[29];
kwork[41]=key[21];
kwork[42]=key[13];
kwork[43]=key[5];
kwork[44]=key[60];
kwork[45]=key[52];
kwork[46]=key[44];
kwork[47]=k
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- DES 算法