天理密码学实验2.docx
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天理密码学实验2
实验报告
学院(系)名称:
计算机与通信工程学院
姓名
吴晋昌
学号
20125879
专业
网络工程
班级
1班
实验项目
实验二DES密码编程
课程名称
密码学实验
课程代码
实验时间
2014.6.410:
10——11:
30
实验地点
计算机软件实验室7-215
批改意见
成绩
教师签字:
一、实验目的
掌握DES加密算法,学会用DES对明文进行加密。
二、实验内容
使用VC++6.0编译器,运用DES对明文进行加密编程。
三、DES简介
1977年1月15日美国正式公布实施的数据加密标准DES(dataencryptionstandard)是一个众所周知的分组密码,其分组长度为64比特(bit),密钥长度也为64比特。
密钥中有8比特奇偶校验位,实际密钥长度只有56比特,尽管DES目前已被高级加密标准AES所取代,但其设计思想仍然值得借鉴。
四、程序代码
#include
#include
#include
//初始置换IP
constintIP[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
};
//初始逆置换IP_1
constintIP_1[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
};
//选择置换PC_1
constintPC_1[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
};
//选择置换PC_2
constintPC_2[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
};
//位选择函数E
constintE[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
};
//置换函数P
constintP[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
};
//S盒
constintS[32][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}
};
//循环左移位数表
constintcirculate[16]={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
//字符串转变成二进制
int*CharToBit(char*s)
{
int*bit;
inti,j,mask;
bit=(int*)malloc(64*sizeof(int));
for(i=0;i<8;i++){
mask=1;
for(j=0;j<8;j++){
bit[i*8+7-j]=s[i]&mask;
s[i]>>=1;
}
}
returnbit;
}
//二进制转字符
char*BitToChar(int*bit)
{
inti,j,k;
char*s;
s=(char*)malloc(9*sizeof(char));
for(i=0;i<8;i++){
k=0;
for(j=0;j<8;j++){
k=k+pow(2,7-j)*bit[8*i+j];
}
s[i]=k;
}
s[8]='\0';
returns;
}
//初始置换
int*InitPermutation(int*bit)
{
int*IP_bit;
inti;
IP_bit=(int*)malloc(64*sizeof(int));
for(i=0;i<64;i++){
IP_bit[i]=bit[IP[i]-1];
}
returnIP_bit;
}
//初始逆置换
int*InverseInitPermutation(int*bit)
{
int*IP_1_bit;
inti;
IP_1_bit=(int*)malloc(64*sizeof(int));
for(i=0;i<64;i++){
IP_1_bit[i]=bit[IP_1[i]-1];
}
returnIP_1_bit;
}
//选择置换pc_1
int*PC_1Permutation(int*key)
{
int*keyPC_1;
inti;
keyPC_1=(int*)malloc(56*sizeof(int));
for(i=0;i<56;i++){
keyPC_1[i]=key[PC_1[i]-1];
//printf("%d\t",keyPC_1[i]);
}
returnkeyPC_1;
}
//选择置换pc_2
int*PC_2Permutation(int*key)
{
int*keyPC_2;
inti;
keyPC_2=(int*)malloc(48*sizeof(int));
for(i=0;i<48;i++){
keyPC_2[i]=key[PC_2[i]-1];
}
returnkeyPC_2;
}
//循环移位操作
int*CircuTransposition(int*keyPC_1,intcir)
{
int*LS;
inti,k,j[2];
LS=(int*)malloc(56*sizeof(int));
for(i=0;i<56;i++){
LS[i]=keyPC_1[i];
}
//循环位移操作
for(k=0;kj[0]=LS[0];
j[1]=LS[28];
for(i=0;i<27;i++){
LS[i]=LS[i+1];
LS[i+28]=LS[i+29];
}
LS[i]=j[0];
LS[i+28]=j[1];
}
returnLS;
}
//位选择函数E
int*BitSelect(int*bit_1)
{
int*bit_E;
inti;
bit_E=(int*)malloc(48*sizeof(int));
for(i=0;i<48;i++){
bit_E[i]=bit_1[E[i]-1];
}
returnbit_E;
}
//模2加运算
int*Xor(int*k,int*bit_E)
{
int*B;
inti;
B=(int*)malloc(48*sizeof(int));
for(i=0;i<48;i++){
if(k[i]==bit_E[i])
B[i]=0;
else
B[i]=1;
}
returnB;
}
//十进制转二进制
int*DecimalToBinary(intdec)
{
int*bin;
inti=0;
intk=dec;
bin=(int*)malloc(4*sizeof(int));
while(i<4){
bin[i]=0;
i++;
}
if(k>=8){
bin[0]=1;
k=k-8;
}
if(k>=4){
bin[1]=1;
k=k-4;
}
if(k>=2){
bin[2]=1;
k=k-2;
}
if(k==1){
bin[3]=1;
}
returnbin;
}
//s盒
int*SSelect(int*B)
{
int*s;
int*bin;
inti,j,k;
s=(int*)malloc(32*sizeof(int));
for(i=0;i<8;i++){
//找到对应的s盒数值
bin=DecimalToBinary(S[B[i*6]*2+B[i*6+1]*1][B[i*6+2]*8+B[i*6+3]*4+B[i*6+4]*2+B[i*6+5]*1]);
s[i*4]=bin[0];
s[i*4+1]=bin[1];
s[i*4+2]=bin[2];
s[i*4+3]=bin[3];
}
returns;
}
//置换函数P
int*PPermutation(int*s)
{
int*p;
inti;
p=(int*)malloc(32*sizeof(int));
for(i=0;i<32;i++){
p[i]=s[P[i]-1];
}
returnp;
}
//K的产生
int**GenerateK(char*key)
{
int**k;//二维数组保存16次迭代的k
int*k_binary;//保存二进制的密钥
int*pc_1_k;//经过pc_1置换后的密钥
int*pc_2_k;//保存经过pc_2置换后密钥
int*ls,*ls_new;//保存经过循环移位操作的值
inti,j;
k=(int**)malloc(16*sizeof(int*));
for(i=0;i<16;i++)
k[i]=(int*)malloc(48*sizeof(int));
k_binary=CharToBit(key);//密钥字符转二进制
pc_1_k=PC_1Permutation(k_binary);//密钥二进制进行pc_1置换
ls_new=pc_1_k;
for(i=0;i<16;i++){
ls=CircuTransposition(ls_new,circulate[i-1]);//取得相应移位后结果
pc_2_k=PC_2Permutation(ls);
for(j=0;j<48;j++){
k[i][j]=pc_2_k[j];//保存到ki表中
}
ls_new=ls;
}
returnk;
}
//DES加密
int*DES(char*s,char*key)
{
int*s_binary;//保存要加密内容的二进制值
int*IP_s;//初始置换后的值
int*IP_1_s;//初始逆置换的值
int**k;//保存ki
int*E_R;//保存R经过E置换的值
int*Xor_E_R_K;//保存ki和R(i-1)置换后经过异或运算的值
int*s_select;//保存经过s盒选择的值
int*f_R_K;//保存f函数的值
inti,j;
intL[32],R[32];//保存明文或者加密i次的明文的左边一半和右边一半
inttemp[32];
int*new_r;//保存和f函数异或运算的值
int*Ciphertext_binary;
Ciphertext_binary=(int*)malloc(64*sizeof(int));
//char*Ciphertext;
s_binary=CharToBit(s);
IP_s=InitPermutation(s_binary);
//for(i=0;i<64;i++)
//printf("%d",IP_s[i]);
//printf("\n");
k=GenerateK(key);
for(i=0;i<32;i++){//将初始置换IP后的值保存为左右两部分
L[i]=IP_s[i];
R[i]=IP_s[i+32];
}
for(i=0;i<16;i++){
for(j=0;j<32;j++){
temp[j]=L[j];//保存原先左边值,用于计算
L[j]=R[j];//右半边值给左边
}
E_R=BitSelect(R);
Xor_E_R_K=Xor(E_R,k[i]);
s_select=SSelect(Xor_E_R_K);
f_R_K=PPermutation(s_select);
new_r=Xor(f_R_K,temp);
for(j=0;j<32;j++){
R[j]=new_r[j];
}
}
for(i=0;i<32;i++){
Ciphertext_binary[i]=L[i];
Ciphertext_binary[i+32]=R[i];
}
/**加密后由于可能出现超出ascii表的值,所以在这里重新转化
**为字符会出问题,这里就不将加密后的结果转化为字符
**Ciphertext=BitToChar(Ciphertext_binary);
*/
returnCiphertext_binary;
}
intmain()
{
char*s;//保存明文
char*key;//保存密钥
int*Ciphertext;//保存密文的二进制值
inti=0;
s=(char*)malloc(8*sizeof(char));
key=(char*)malloc(9*sizeof(char));
printf("*****************************DES加密算法*************************\n\n");
printf("请输入明文(8字节):
");
gets(s);
printf("\n");
getchar;
printf("请输入密钥(8字节):
");
gets(key);
Ciphertext=DES(s,key);
printf("\n");
printf("密文:
");
i=0;
while(i<64){
printf("%d",Ciphertext[i]);
i++;
}
printf("\n");
return;
}
五、实验结果