RC4加密算法

//程序开始

#include<stdio.h>

#include<string.h>

 

typedefunsignedlongULONG;

 

/*初始化函数*/

voidrc4_init(unsignedchar*s,unsignedchar*key,unsignedlongLen)

{

inti=0,j=0;

chark[256]={0};

unsignedchartmp=0;

for(i=0;i<256;i++)

{

s[i]=i;

k[i]=key[i%Len];

}

for(i=0;i<256;i++)

{

j=(j+s[i]+k[i])%256;

tmp=s[i];

s[i]=s[j];//交换s[i]和s[j]

s[j]=tmp;

}

}

 

/*加解密*/

voidrc4_crypt(unsignedchar*s,unsignedchar*Data,unsignedlongLen)

{

inti=0,j=0,t=0;

unsignedlongk=0;

unsignedchartmp;

for(k=0;k<Len;k++)

{

i=(i+1)%256;

j=(j+s[i])%256;

tmp=s[i];

s[i]=s[j];//交换s[x]和s[y]

s[j]=tmp;

t=(s[i]+s[j])%256;

Data[k]^=s[t];

}

}

 

intmain()

{

unsignedchars[256]={0},s2[256]={0};//S-box

charkey[256]={"justfortest"};

charpData[512]="这是一个用来加密的数据Data";

ULONGlen=strlen(pData);

inti;

 

printf("pData=%s\n",pData);

printf("key=%s,length=%d\n\n",key,strlen(key));

rc4_init(s,(unsignedchar*)key,strlen(key));//已经完成了初始化

printf("完成对S[i]的初始化，如下：\n\n");

for(i=0;i<256;i++)

{

printf("%02X",s[i]);

if(i&&(i+1)%16==0)putchar('\n');

}

printf("\n\n");

for(i=0;i<256;i++)//用s2[i]暂时保留经过初始化的s[i]，很重要的！！！

{

s2[i]=s[i];

}

printf("已经初始化，现在加密:\n\n");

rc4_crypt(s,(unsignedchar*)pData,len);//加密

printf("pData=%s\n\n",pData);

printf("已经加密，现在解密:\n\n");

//rc4_init(s,(unsignedchar*)key,strlen(key));//初始化密钥

rc4_crypt(s2,(unsignedchar*)pData,len);//解密

printf("pData=%s\n\n",pData);

return0;

}