?

c^b=a

#include "stdio.h"
#include "stdlib.h"

void main(int argc,char *argv[])
{
?FILE *fp1,*fp2;
?char c,ch;
?long j;
?if(3!=argc)
?{
? printf("Command error/n");
? exit(1);
?}

?if((fp1=fopen(argv[1],"rb"))==NULL)
?{
? printf("Can not open the source file/n");
? exit(1);
?}

?if(NULL==(fp2=fopen(argv[2],"wb")))
?{
? printf("Can not open the aim file/n");
? exit(1);
?}

?printf("Please input the password:/n");
?scanf("%i",&j);
?srand(j);
?ch=fgetc(fp1);
?while(!feof(fp1))
?{
? c=rand();
? ch=ch^c;
? fputc(ch,fp2);
? ch=fgetc(fp1);
?}

?fclose(fp1);
?fclose(fp2);
}