实验四加密解密软件的使用Word格式文档下载.docx
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然后,通过另一个异或运算,函数f的输出与左半部分结合,其结果成为新的右半部分,原来的右半部分成为新的左半部分。
将该操作重复16次,就实现了。
2,模块分析
(1)DES轮密钥的生成
1.1轮密钥生成流程图如下图所示:
1.2置换选择1
将输入的64位密钥根据PC_1表进行置换。
intTransform_1(charkey[64],chartemp[56])
{inti;
intPC_1[56]={56,48,40,32,24,16,8,0,57,49,41,33,25,17,
9,1,58,50,42,34,26,18,10,2,59,51,43,35,
62,54,46,38,30,22,14,6,61,53,45,37,29,21,
13,5,60,52,44,36,28,20,12,4,27,19,11,3};
for(i=0;
i<
56;
i++)
{
temp[i]=key[PC_1[i]];
}
return0;
}
1.3循环左移
经置换选择1变换后输出的56位密钥被分成两个28位的值C0和D0。
每个循环中Ci-1和Di-1分别经过循环左移,这些经过移位的值再作为下一循环的输入。
根据循环左移表可知,移位只有一位或者两位,所以用if进行判断来执行左移。
intRing_shift_left(chardata[56],inttime)
{intMove_Time[16]={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
//循环左移位数
chartemp[56];
inti,j;
if(Move_Time[time]==2){
temp[26]=data[0];
temp[27]=data[1];
temp[54]=data[28];
temp[55]=data[29];
for(j=0;
j<
28-2;
j++){
temp[j]=data[j+2];
}
for(j=28;
56-2;
}
else{
temp[27]=data[0];
temp[55]=data[28];
28-1;
temp[j]=data[j+1];
56-1;
temp[56]='
\0'
;
i++){
data[i]=temp[i];
1.4置换选择2
置换选择2属于压缩型P盒,它将56位输入成48位输出,作为轮密钥输入函数F。
intTransform_2(charkey[56],chartemp[48])
{
inti;
intPC_2[48]={13,16,10,23,0,4,2,27,14,5,20,9,22,18,11,3,
25,7,15,6,26,19,12,1,40,51,30,36,46,54,29,39,
50,44,32,47,43,48,38,55,33,52,45,41,49,35,28,31};
48;
temp[i]=key[PC_2[i]];
(2)初始置换
intIP_Table[64]={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,
56,48,40,32,24,16,8,0,58,50,42,34,26,18,10,2,
60,52,44,36,28,20,12,4,62,54,46,38,30,22,14,6};
(3)拓展置换E
intexpand(chardata[32],chartemp[48])//R32位
{intE_Table[48]={31,0,1,2,3,4,3,4,5,6,7,8,
7,8,9,10,11,12,11,12,13,14,15,16,
15,16,17,18,19,20,19,20,21,22,23,24,
23,24,25,26,27,28,27,28,29,30,31,0};
for(inti=0;
temp[i]=data[E_Table[i]];
temp[48]='
(4)异或函数1
intExclusive(chardata[48],charsubkeys[16][48],charYiHuo[48],inti)
{for(intm=0;
m<
m++)
if(data[m]==subkeys[i][m])
YiHuo[m]='
0'
else
1'
(5)选择压缩变换S盒代替
intDES_S(charYiHuo[48],charSSS[32])
{inthang,lie,shu;
SSS[0]='
/*S盒*/
intS[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}}};
for(intj=0;
8;
j++)
hang=(YiHuo[6*j+0]-'
)*2+(YiHuo[6*j+5]-'
)*1;
lie=(YiHuo[6*j+1]-'
)*8+(YiHuo[6*j+2]-'
)*4+\
(YiHuo[6*j+3]-'
)*2+(YiHuo[6*j+4]-'
shu=S[j][hang][lie];
switch(shu)
{
case0:
strcat(SSS,"
0000"
);
break;
case1:
0001"
case2:
0010"
case3:
0011"
case4:
0100"
case5:
0101"
case6:
0110"
case7:
0111"
case8:
1000"
case9:
1001"
case10:
1010"
case11:
1011"
case12:
1100"
case13:
1101"
case14:
1110"
case15:
1111"
(6)换运算P
intDES_P(charSSS[32])
{intP_Table[32]={15,6,19,20,28,11,27,16,0,14,22,25,4,17,30,9,
1,7,23,13,31,26,2,8,18,12,29,5,21,10,3,24};
chartemp[32];
for(intm=0;
32;
temp[m]=SSS[P_Table[m]];
memcpy(SSS,temp,32);
(7)异或函数2
intExclusive2(charleft[32],charSSS[32],charYiHuo2[32])
{YiHuo2[0]='
if(left[m]==SSS[m])
YiHuo2[m]='
(8)逆初始变换
intIP_1_Transform(chardata[64])
chartemp[64];
intIP_1_Table[64]={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,
33,1,41,9,49,17,57,25,32,0,40,8,48,16,56,24};
64;
temp[i]=data[IP_1_Table[i]];
memcpy(data,temp,64);
data[64]='
\n'
3,代码测试结果:
(1)输入明文与密钥
(2)输出密文
(3)解密
4,软件使用
(1)登录界面
(2)输入密码及问题提示
(3)成功加密文件
(4)输入密钥解密
三,实验总结
在编写代码中要注意一些问题。
首先,要注意的是初始置换表,逆初始置换表,拓展变换表,P置换表,置换选择1表,置换选择2表的数值要从0开始编号,且不能出错。
其次,编写过程中要思路清晰,一个模块一个模块地进行运行分析。
最后,解密的过程只要把子密匙的输入改为逆序的即可。