RC4 流密码算法之 C 语言实现RC4 加密算法RC4 算法的原理很简单，包括初始化算法（KSA）和伪随机子密码生成算法（PRGA)两大部分。假设 S-box 长度和密钥长度均为为 n。先来看看算法的初始化部分（用类 C 伪代码表示）： for (i=0; i#include#includevoid swap(unsigned char *s1,unsigned char *s2){char temp;temp=*s1;*s1=*s2;*s2=temp;}void re_S(unsigned char *S){unsigned int i;for(i=0;i<256;i++) S[i]=i;}void re_T(unsigned char *T,char *key){int i;int keylen;keylen=strlen(key);for(i=0;i<256;i++) T[i]=key[i%keylen];}void re_Sbox(unsigned char *S,unsigned char *T){int i;int j=0;for(i=0;i<256;i++){ j=(j+S[i]+T[i])%256; swap(&S[i],&S[j]);}}void re_RC4(unsigned char *S,char *key){char T[255]={0};re_S(S);re_T(T,key);re_Sbox(S,T);}void RC4(FILE *readfile,FILE *writefile,char *key){ unsigned char S[255]={0};unsigned char readbuf[1];int i,j,t; re_RC4(S,key);i=j=0;while(fread(readbuf,1,1,readfile)){ i = (i + 1) % 256; j = (j + S[i]) % 256; swap(&S[i],&S[j]); t = (S[i] + (S[j] % 256)) % 256; readbuf[0]=readbuf[0]^S[t]; fwrite(readbuf,1,1,writefile); memset(readbuf,0,1);}printf("加密|解密成功!!!\n");}int main(int argc,char *argv[]){char *Filename1,*Fi...
