vigenere.cpp

C语言 Vigenere 加密

#include<stdio.h> 
#include<conio.h>
#include<windows.h>
#include<math.h> 
void menu()/*菜单*/ 
{ 
     
   printf("==============================================================================="); 
   printf(" Encrypt the file enter 1  \n"); 
   printf(" Decrypt the file enter 2  \n"); 
   printf(" Quit enter 3  \n"); 
   printf("==============================================================================="); 
   printf(" Please select a item: "); 
   return; 
} 
   

   char encrypt(char ch1,char ch2)/*加密程序*/ 
   { 
    if(ch1>='A'&&ch1<='Z'&&ch2>='A'&&ch2<='Z') 
	{ 
      return 'A'+(ch1-'A'+ch2-'A')%26; 
	} 
     if(ch1>='a'&&ch1<='z'&&ch2>='a'&&ch2<='z') 
	 { 
      return 'a'+(ch1-'a'+ch2-'a')%26; 
	 } 
      return ch1; 
   } 

    char decrypt(char ch1,char ch2)/*解密程序*/ 
   { 
    if(ch1>='A'&&ch1<='Z'&&ch2>='A'&&ch2<='Z') 
	{ 
      return 'A'+(ch1-'A'+26-(ch2-'A'))%26; 
	} 
    if(ch1>='a'&&ch1<='z'&&ch2>='a'&&ch2<='z') 
	{ 
      return 'a'+(ch1-'a'+26-(ch2-'a'))%26; 
	} 
      return ch1; 
   }

      
	
  void 	main() 
	{ 
      int i; 
       char key[5]; 
       char ch; 
       FILE *in,*out; 
       char infile[10],outfile[10]; 

       void   textbackground(int   BLACK);    
       void   textcolor(int   LIGHTGREEN);   
     
        Sleep(3); 

      menu(); 

      ch=getch(); 

      while(ch!='3') 
	  { 
        if(ch=='1') 
		{ 
            
            printf(" Please input the infile: \n"); 
            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: \n"); 
              scanf("%s",key);/*输入加密密码*/ 

               printf(" Please input the outfile: \n"); 
               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); 
			   } 

                  i=0; 
               while(!feof(in))   //当不是文件的结尾时
			   { 
                 fputc(encrypt(fgetc(in),key[i%strlen(key)]),out);   //存在问题！！！  为何生成密文的结尾都有怪异的符号？
                  i++; 
			   } 

               fclose(in); 
               fclose(out); 
               printf("Encrypt successful! \n"); 
               Sleep(1); 
		} 
               if(ch=='2') 
			   { 
                   
                   printf(" Please input the infile: \n"); 
                   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: \n"); 
                 scanf("%s",key);/*输入解密密码*/ 

                 printf(" Please input the outfile: \n"); 
                 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); 
			   } 

                  i=0; 
                  while(!feof(in)) 
				  { 
                    fputc(decrypt(fgetc(in),key[i%strlen(key)]),out); 
                    i++; 
				  } 

                  fclose(in); 
                  fclose(out); 
                  printf("Decrypt successful! \n"); 
                  Sleep(1); 
			   } 
                  printf("\n");
				  menu(); 
                  ch=getch(); 
	  } 

               

               printf("Good Bye! \n"); 
               Sleep(3); 
	}