凯撒加密算法C语言实现.doc

凯撒加密算法C语言实现#include#include char encrypt(char ch,int n)/*加密函数，把字符向右循环移位n*/while(ch=A&ch=a&ch=z)return (a+(ch-a+n)%26);return ch;void menu()/*菜单，1.加密，2.解密，3.暴力破解，密码只能是数字*/clrscr();printf(n=);printf(n1.Encrypt the file);printf(n2.Decrypt the file);printf(n3.Force decrypt file);printf(n4.Quitn);printf(=n);printf(Please select a item:);return;void logo()/*显示版权信息*/printf(nZhensoft Encryption Version:1.0.0);printf(nCopyright (C) 2004 Zhensoft Corp.n);printf(nn);return;main()int i,n;char ch0,ch1;FILE *in,*out;char infile20,outfile20;textbackground(BLACK);textcolor(LIGHTGREEN);clrscr();logo();sleep(3);/*等待3秒*/menu();ch0=getch();while(ch0!=4)if(ch0=1) clrscr(); printf(nPlease input the infile:); scanf(%s,infile);/*输入需要加密的文件名*/ if(in=fopen(infile,r)=NULL) printf(Can not open the infile!n);printf(Press any key to exit!n);getch();exit(0); printf(Please input the key:); scanf(%d,&n);/*输入加密密码*/ printf(Please input the outfile:); scanf(%s,outfile);/*输入加密后文件的文件名*/ if(out=fopen(outfile,w)=NULL) printf(Can not open the outfile!n);printf(Press any key to exit!n);fclose(in);getch();exit(0); while(!feof(in)/*加密*/ fputc(encrypt(fgetc(in),n),out); printf(nEncrypt is over!n); fclose(in); fclose(out); sleep(1);if(ch0=2) clrscr(); printf(nPlease input the infile:); scanf(%s,infile);/*输入需要解密的文件名*/if(in=fopen(infile,r)=NULL) printf(Can not open the infile!n);printf(Press any key to exit!n);getch();exit(0); printf(Please input the key:); scanf(%d,&n);/*输入解密密码（可以为加密时候的密码）*/ n=26-n; printf(Please input the outfile:); scanf(%s,outfile);/*输入解密后文件的文件名*/ if(out=fopen(outfile,w)=NULL) printf(Can not open the outfile!n);printf(Press any key to exit!n);fclose(in);getch();exit(0); while(!feof(in) fputc(encrypt(fgetc(in),n),out); printf(nDecrypt is over!n); fclose(in); fclose(out); sleep(1);if(ch0=3) clrscr(); printf(nPlease input the infile:); scanf(%s,infile);/*输入需要解密的文件名*/ if(in=fopen(infile,r)=NULL) printf(Can not open the infile!n);printf(Press any key to exit!n);getch();exit(0); printf(Please input the outfile:); scanf(%s,outfile);/*输入解密后文件的文件名*/ if(out=fopen(outfile,w)=NULL) printf(Can not open the outfile!n);printf(Press any key to exit!n);fclose(in);getch();exit(0); for(i=1;i=25;i+)/*暴力破解过程，在察看信息正确后，可以按Q或者q退出*/ rewind(in);rewind(out);clrscr();printf(=n);printf(The outfile is:n);printf(=n);while(!feof(in) ch1=encrypt(fgetc(in),26-i); putch(ch1); fputc(ch1,out);printf(n=n);printf(The current key is: %d n,i);/*显示当前破解所用密码*/printf(Press Q to quit and other key to continue.n);printf(=n);ch1=getch();if(ch1=q|ch1=Q)/*按Q或者q时退出*/ clrscr(); logo();printf(nGood Bye!n); fclose(in); fclose(out); sleep(3); exi