RC4流密码算法之C语言实现

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<n; i++)s=i;在初始化的过程中，密钥的主要功能是将S-box搅乱，i确保S-box的每个元素都得到处理，j保证S-box的搅乱是随机的。

而不同的S-box在经过伪随机子密码生成算法的处理后可以得到不同的子密钥序列，并且，该序列是随机的：j=0;for (i=0; i<n; i++){j=(j+s+k)%256;swap(s, s[j]);}i=j=0;得到的子密码sub_k用以和明文进行xor运算，得到密文，解密过程也完全相同。

根据目前的分析结果，没有任何的分析对于密钥长度达到128位的RC4有效，所以，RC4是目前最安全的加密算法之一，大家可以放心使用！while (明文未结束){++i%=n;j=(j+s)%n;swap(s, s[j]);sub_k=s((s+s[j])%n);}位长可以自己随意设置，将256设置为你希望的即可我的C语言源码：平台：windowsXP，VC++6.0有什么大家可以讨论的地方请留言或发邮件至我邮箱：#include<stdio.h>#include<stdlib.h>#include<string.h>void 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,*Filename2; char *key;FILE *file1,*file2;Filename1 = argv[1];Filename2 = argv[2];key=argv[3];if ( argc == 4){printf("**********************正在加密中*******************\n"); }else{printf("输入格式：\n");printf("文件名|加密或解密文件名|存放文件名|密钥\n");return -1;}if ((file1= fopen(Filename1,"rb")) == NULL|| (file2 =fopen(Filename2,"wb"))==NULL){printf("Can't open file\n");return -1;}RC4(file1,file2,key);fclose(file1);fclose(file2);return 0;}加密解密算法RC5- -#include <iostream.h>#include "math.h"#include <stdio.h>static const w=32;static const r=12;static const b=16;static const t=26;//2*r+2=12*2+2static const c=4; //r*8/b = 16*8/32typedef unsigned long int FOURBYTEINT;typedef unsigned char BYTE;/*** 循环左移和右移函数* x : 被循环的数* y : 将要循环的位数*/#define ROTL(x,y) (((x)<<(y&(w-1))) | ((x)>>(w-(y&(w-1)))))#define ROTR(x,y) (((x)>>(y&(w-1))) | ((x)<<(w-(y&(w-1)))))/** 产生子密钥的函数*/void generateChildKey(unsigned char*,FOURBYTEINT*);/** 产生初试密钥的函数*/void InitialKey(unsigned char* KeyK,int b){for(int i=0;i<b;i++){KeyK[i]=0;}int intiSeed=3;KeyK[0]=intiSeed;for(i=1;i<b;i++){KeyK[i] = (BYTE) ( ((int)(pow(3,i)))%(255-i) );//KeyK[i] = KeyK[i-1]*intiSeed % 256;}}/** 取最近奇数的函数*/int Odd(double fl){int floorOffl = (int)floor(fl);if (floorOffl% 2==0) return floorOffl+1;return floorOffl;}/** 加密函数*/void Encipher(FOURBYTEINT* In,FOURBYTEINT* Out,FOURBYTEINT* S){ FOURBYTEINT X,Y;X = In[0]+S[0];Y = In[1]+S[1];for(int i=1;i<=r;i++){X=ROTL((X^Y),Y) + S[2*i];Y=ROTL((Y^X),X) + S[2*i+1];}Out[0]=X;Out[1]=Y;}/** 解密函数*/void Decipher(FOURBYTEINT* In,FOURBYTEINT* Out,FOURBYTEINT* S){FOURBYTEINT X,Y;X = In[0];Y = In[1];for(int i=r;i>0;i--){Y = ROTR(Y-S[2*i+1],X)^X;X = ROTR(X-S[2*i],Y)^Y;}Out[0]=X - S[0];Out[1]=Y - S[1];}/** 主函数*/void main(){FOURBYTEINT ChildKeyS[2*r+2]; //64bit unsigned char KeyK[b];//8bit=byteInitialKey(KeyK,b);int k;generateChildKey(KeyK,ChildKeyS); FOURBYTEINT Source[2]={8888,6666};//cout<<Source[0]<<" "<<Source[1]<<endl;printf("加密以前的明文:");for (k=0;k<2;k++) {printf("%.8lX ",Source[k]);}FOURBYTEINT Dest[2];Encipher(Source,Dest,ChildKeyS);//cout<<Dest[0]<<" "<<Dest[1]<<endl; printf("\n");printf("加密以后的密文:");for (k=0;k<2;k++) {printf("%.8lX ",Dest[k]);}printf("\n");Decipher(Dest,Source,ChildKeyS);//cout<<Source[0]<<" "<<Source[1]<<endl; printf("解密以后的明文:");for (k=0;k<2;k++) {printf("%.8lX ",Source[k]);}printf("\n");/*printf("加密以前的明文:");for (k=0;k<6;k++) {printf("%.8lX ",mingwen_org[k]);}printf("\n");printf("加密以后的密文:");for (k=0;k<6;k++) {printf("%.8lX ",miwen[k]);}printf("\n");printf("解密以后的明文:");for (k=0;k<6;k++) {printf("%.8lX ",mingwen_final[k]);}printf("\n");*/}void generateChildKey(unsigned char* KeyK,FOURBYTEINT* ChildKeyS) {const double e = 2.718281828459;const double Phia = 1.618033988749;//int PW = Odd((e-1)*pow(2,w));int PW = 0xb7e15163;//int QW = Odd((Phia -1)*pow(2,w));int QW = 0x9e3779b9;int i;FOURBYTEINT L[c];//初试化数组SChildKeyS[0]=PW;for ( i=1;i<t;i++){ChildKeyS[i]=(ChildKeyS[i-1]+ QW);//% (2<<w)不需要}//transform from K to L//initialization Lfor(i=0;i<c;i++){L[i]=0;}int u = w/8;for (i=b-1;i!=-1; i--)L[i/u] = (L[i/u]<<8)+KeyK[i];for (i=0;i<4;i++)printf("%.8X\n",L[i]);/generate child keysFOURBYTEINT A,B,X,Y;A=B=X=Y=0;for(i=0;i<3*t;i++){X = ChildKeyS[A] = ROTL(ChildKeyS[A]+X+Y,3);A = (A+1) % t;Y = L[B] = ROTL(L[B]+X+Y,(X+Y));B = (B+1) % c;}/*for (i=0;i<t;i++){printf("%.8X",ChildKeyS[i]);printf("\n");}*/}。