crypt.cpp

两个加密小程序

#include "stdio.h"
#include "string.h"
#define right 5
#define maxpassword 20
#define minpassword 6
#define maxlen 20

void Create();
void Load();
char secure(char);
char desecure(char);

void main()
{
     int choice;
     printf("Please enter your choice:\n");
     printf("0:To quit;\n");
     printf("1:To create a security file;\n");
     printf("2:To load a security file .\n");

     cir:
     printf("Your choice:");
     scanf("%d",&choice);
  
	 if(choice==0)
        return;
  
	 if(choice==1)
     {
         Create();
         printf("\n");
         goto cir;
     }
     else
	    if(choice==2)
     {
         Load();
         printf("\n");
         goto cir;
     }
     else
     {
         printf("Invalid input!\n");
         goto cir;
     }
}

void Create()

{

     FILE *fp;

     char *p,ch,s[maxpassword],*t,temp,path[maxlen];

     recre:

     printf("Please enter the path where you wanna the file to be:");

     scanf("%s",path);

     p=path;

     if(*p<'C'||*p>'F'||*(p+1)!=':'||*(p+2)!=92||strlen(p)>30||strlen(p)<4)

     {
         printf("Invalid input!\n");
         goto recre;
     }
     if((fp=fopen(p,"wb"))==NULL)
     {
         printf("Error!");
         return;
     }

     printf("Please enter the password:");
     an:
     p=s;
     lp:

     _asm {
     mov ah,00h
     int 16h
     cmp al,0dh
     je exit
     mov temp,al
     mov dl,'*'
     mov ah,02h
     int 21h
     }

     *p=temp;
     p++;
     goto lp;
     exit:

     *p='\0';
     p=s;
     if(strlen(p)>maxpassword||strlen(p)<minpassword)
     {
         printf("The password is too long or too short,please reinput!\n");
         goto an;
     }

     while(*p!='\0')
     {
         ch=*p;
         ch=secure(ch);
         p++;
         fputc(ch,fp);
     }

     ch='\n';

     ch=secure(ch);

     fputc(ch,fp);

     printf("\nPlease enter the information,end with char '#':");

     ch=getchar();

     ch=getchar();

     while(ch!='#')
     {
         ch=secure(ch);
         fputc(ch,fp);
         ch=getchar();
     }
     ch=secure(ch);
     fputc(ch,fp);
     fclose(fp);
}

void Load()
{
     FILE *fp;
     char *p,ch,s[maxpassword],tc,temp[maxpassword],pass[maxpassword],sign=secure('\n');
     int i=0,t=0,lenth=0;
     rece:
     printf("Please enter the path where you wanna to load:");
     scanf("%s",p);
     if(*p<'C'||*p>'F'||*(p+1)!=':'||*(p+2)!=92||strlen(p)>30||strlen(p)<4)
     {
         printf("Invalid input!\n");
         goto rece;
     }

     if((fp=fopen(p,"rb"))==NULL)
     {
        printf("Error!");
        return;
     }

     printf("Please enter the password:");
     an:
     p=s;
     lp:
     _asm {
     mov ah,00h
     int 16h
     cmp al,0dh
     je exit
     mov tc,al
     mov dl,'*'
     mov ah,02h
     int 21h
     }

     *p=tc;
     p++;
     goto lp;
     exit:
     *p='\0';
     p=s;

     if(strlen(p)>maxpassword||strlen(p)<minpassword)
     {
         printf("The password is too long or too short,please reinput!\n");
         goto an;
     }

     while(*p!='\0')
     {
         temp[i]=secure(*p);
         p++;
         i++;
     }

     temp[i]='\0';

     printf("\n");

     ch=fgetc(fp);

     while(ch!=sign)
     {
         pass[t]=ch;
         t++;
         ch=fgetc(fp);
     }

     pass[t]='\0';
     ch=desecure(ch);

     if(!strcmp(temp,pass))
     {
         while(ch!='#')
         {
              ch=fgetc(fp);
              ch=desecure(ch);
              if(ch!='#')
              putchar(ch);
         }
     }
     else
     printf("The password is incorrect!\n");
     fclose(fp);
}

char secure(char c)

{
     if(c+right>254)
         return c-255+right;
     else
         return c+right;
}

char desecure(char c)
{
     if(c<right)
         return 255-right;
     else
         return c-right;
}