enc.c

文件加密使用,可以实现对PC上文件进行加密解密功能

#include<dos.h>
#include<graphics.h>
#include<alloc.h>
#include<string.h>
#include<sys\stat.h>
#include<fcntl.h>
#include<sys\types.h>
#include<stdio.h>
#include<stdlib.h>



void displaymenu(char **menu, int count, int x1, int y1);
void savemenu(char **menu, char **buffer, int width, int count, int x1, int y1);
int getresponse(char **menu, char **buffer, int width, int count, int x1, int y1);
void highlight(char **buffer, int ch, int h, int x1, int y1);
void dehighlight(char **buffer, int ch, int h, int x1, int y1);
void getmousepos(int *button, int *x, int *y);
void initmouse();
void hidemouseptr();
void showmouseptr();
unsigned long encrypt();
void setmousepos(int x, int y);


char *menu[]={"Encrypt","Decrypt","Help","Exit"};
char source[50],pass[20],dest[50];

void main()
{
 int gd=DETECT,gm,choice=1,width=0,i,count,ret_code;
 char **buffer;
 initgraph(&gd,&gm,"c:\\tc\\bgi");
 initmouse();
 showmouseptr();
 settextstyle(0,0,5);
 outtextxy(300,150,"EnCrYpT");
 gotoxy(38,13);
 printf(" CoNcEpT:  [e-mail]");
 count=sizeof(menu)/sizeof(char *);
 settextstyle(TRIPLEX_FONT,0,3);
 displaymenu(menu,count,100,300);
 for(i=0;i<count;i++)
 {
  if(textwidth(menu[i])>width)
	width=textwidth(menu[i]);
 }
 buffer=malloc(sizeof(menu));
 savemenu(menu,buffer,width,count,100,100);
 while(choice!=4)
 { // 1-encrypt   2-decrypt
  choice=getresponse(menu,buffer,width,count,100,100);
  switch(choice)
  {
   case 1: setmousepos(400,150);  // just for fine adjustment
	   setfillstyle(SOLID_FILL,0);
	   bar(50,250,600,450);
	   rectangle(50,300,600,375);
	   gotoxy(20,20);
	   printf("Enter the path of file to be encrypted:\n ");
	   gotoxy(10,22);
	   printf("Path: ");
	   scanf("%s",source);

	   bar(50,300,600,375);

	   rectangle(50,300,600,375);
	   gotoxy(20,20);
	   printf("Enter password for the file to be encrypted:\n ");
	   gotoxy(10,22);
	   printf("Password: ");
	   scanf("%s",pass);

	   bar(50,300,600,375);

	   rectangle(50,300,600,375);
	   gotoxy(20,20);
	   printf("Enter path of the output encrypted file:\n ");
	   gotoxy(10,22);
	   printf("Path: ");
	   scanf("%s",dest);

	   ret_code=encrypt();
	   if(ret_code!=0)
	   {
	    bar(50,300,600,375);
	    rectangle(50,300,600,375);
	    gotoxy(35,20);
	    printf("SUCCESS: ");
	    gotoxy(10,22);
	    printf("%s encrypted to %s using the key: %s",source,dest,pass);
	   }
	   else
	   {
	    bar(50,300,600,375);
	    rectangle(50,300,600,375);
	    gotoxy(35,20);
	    printf("FAILURE: ");
	    gotoxy(10,22);
	    printf("The selected file(s) couldn't be opened, please verify the path");
	   }
	   break;

   case 2: setmousepos(400,150);
	   setfillstyle(SOLID_FILL,0);
	   bar(50,250,600,450);
	   rectangle(50,300,600,375);
	   gotoxy(20,20);
	   printf("Enter the path of already encrypted file:\n ");
	   gotoxy(10,22);
	   printf("Path: ");
	   scanf("%s",source);

	   bar(50,300,600,375);

	   rectangle(50,300,600,375);
	   gotoxy(20,20);
	   printf("Enter password of the ecrypted file:\n ");
	   gotoxy(10,22);
	   printf("Password: ");
	   scanf("%s",pass);

	   bar(50,300,600,375);

	   rectangle(50,300,600,375);
	   gotoxy(20,20);
	   printf("Enter path of the output dencrypted file:\n ");
	   gotoxy(10,22);
	   printf("Path: ");
	   scanf("%s",dest);

	   ret_code=encrypt();
	   if(ret_code!=0)
	   {
	    bar(50,300,600,375);
	    rectangle(50,300,600,375);
	    gotoxy(35,20);
	    printf("SUCCESS: ");
	    gotoxy(10,22);
	    printf("%s decrypted to %s using the key: %s",source,dest,pass);
	   }
	   else
	   {
	    bar(50,300,600,375);
	    rectangle(50,300,600,375);
	    gotoxy(35,20);
	    printf("FAILURE: ");
	    gotoxy(10,22);
	    printf("The selected file(s) couldn't be opened, please verify the path");
	   }
	   break;

   case 3: setmousepos(400,150);
	   setfillstyle(SOLID_FILL,0);
	   bar(50,250,600,450);
	   rectangle(50,250,600,450);
	   gotoxy(37,17);
	   printf("HELP: ");
	   gotoxy(10,19);
	   printf("Encrypt: Enter the full path name of both, the source file and");
	   gotoxy(19,20);
	   printf("the destination file. Enter a numerical password only");
	   gotoxy(19,21);
	   printf("as the encrypting/decrypting algorithm can only use");
	   gotoxy(19,22);
	   printf("numerical values.");
	   gotoxy(10,23);
	   printf("Decrypt: Only a previously encrypted file can be decrypted using");
	   gotoxy(19,24);
	   printf("the same password as was used during encryption. Usage");
	   gotoxy(19,25);
	   printf("of wrong password will again encrypt the file.");
	   break;

  }
 }
}

void displaymenu(char **menu, int count, int x1, int y1)
{
 int i,h;
 h=textheight(menu[0]);
 for(i=0;i<count;i++)
 {
  outtextxy(x1,97+i*(h+5),menu[i]);
 }
}

void savemenu(char **menu, char **buffer, int width, int count, int x1, int y1)
{
 int i,x2,yy1,yy2,area,h;
 h=textheight(menu[0]);
 for(i=0;i<count;i++)
 {
  x2=x1+width;
  yy1=y1+i*(h+5);
  yy2=y1+(i+1)*(h+5);
  area=imagesize(x1,yy1,x2,yy2);
  buffer[i]=malloc(area);
  getimage(x1,yy1,x2,yy2,buffer[i]);
 }
}

int getresponse(char **menu, char **buffer, int width, int count, int x1, int y1)
{
 int choice=1, prevchoice=0, x,y,x2,y2,button;
 int in,i,h;

 h=textheight(menu[0]);
 y2=y1+count*(h+5);
 x2=x1+width;
 rectangle(x1-5, y1-5, x2+5, y2+5);
 while(1)
 {
  getmousepos(&button,&x,&y);
  if(x>=x1&&x<=x2&&y>=y1&&y<=y2)
  {
   in=1;
   for(i=1;i<=count;i++)
   {
    if(y<=y1+i*(h+5))
    {
     choice=i;
     break;
    }
   }
   if(prevchoice!=choice)
   {
    hidemouseptr();
    highlight(buffer,choice,h,x1,y1);
    if(prevchoice)
	dehighlight(buffer,prevchoice,h,x1,y1);

    prevchoice=choice;
    showmouseptr();
   }
   if((button&1)==1)
   {
    while((button&1)==1)
	getmousepos(&button,&x,&y);
    if(x>=x1&&x<=x2&&y>=y1&&y<=y2)
	return(choice);
   }
  }
  else
  {
   if(in==1)
   {
    in=0;
    prevchoice=0;
    hidemouseptr();
    dehighlight(buffer,choice,h,x1,y1);
    showmouseptr();
   }
  }
 }
}

void highlight(char **buffer, int ch, int h, int x1, int y1)
{
 putimage(x1,y1+(ch-1)*(h+5),buffer[ch-1],NOT_PUT);
}


void dehighlight(char **buffer, int ch, int h, int x1, int y1)
{
 putimage(x1,y1+(ch-1)*(h+5),buffer[ch-1],COPY_PUT);
}

void initmouse()
{
 _AX=0;
 geninterrupt(0x33);
}

void showmouseptr()
{
 _AX=1;
 geninterrupt(0x33);
}

void hidemouseptr()
{
 _AX=2;
 geninterrupt(0x33);
}

void getmousepos(int *button, int *x, int *y)
{
 _AX=3;
 geninterrupt(0x33);
 *button=_BX;
 *x=_CX;
 *y=_DX;
}

void setmousepos(int x, int y)
{
 _AX=4;
 _CX=x;
 _DX=y;
 geninterrupt(0x33);
}

unsigned long encrypt()
{

 int in,out;
 char buffer[512];
 int bytes=0,i;
 unsigned long key=0,num_of_bytes=0;
 char *endptr;

  key=strtoul(pass,&endptr,10);

  in=open(source,O_RDONLY|O_BINARY);


  if(in==-1)
  {
   return(0);
  }
  else
  {
   out=open(dest,O_CREAT|O_BINARY|O_WRONLY,S_IWRITE);
   if(out==-1)
	return 0;
  }
  while(1)
  {
   bytes=read(in,buffer,512);
   if(bytes>0)
   {
    num_of_bytes+=bytes;
    for(i=0;i<bytes;i++)
    {
     buffer[i]=buffer[i]^key;
    }
    write(out,buffer,bytes);
   }
   else break;
  }
  close(in);
  close(out);

 return num_of_bytes;
}