/**************************************************************
*     Basic xor encryption program by spade89 :)              *
*       this code is for everyhuman no copyrights             *
*     feel free to modify or duplicate as much as you want.   *
*                                                             *
***************************************************************
*/
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
#include<string.h>
int encrypt(char *,char *);
int decrypt(char *,char *);
long filesize(FILE *);
int main(){
         begining:
        unsigned char key[128],filename[64];
       textcolor(LIGHTGREEN);
      //startup:
         cprintf("BASIC XOR ENCRYPTION BY SPADE %c") ;cout<<endl;
         for(int i=0;i<80;i++)cprintf("%c",6);
       cout<<endl;
//   synchronize i/o
      cin.tie(&cout);
          cout<<"Enter filename:\n";
  //get filename
        cin>>filename;
           cout<<"Enter key:\n";
           //get encryption decryption key
           cin>>key;

           char op;
           cout<<"Enter option<Encrypt/Decrypt>:\n";
           //see what the user wants us to do
              op=getch();

           switch(op){

           case 'd':
           case 'D':
           decrypt(filename,key);
           break;
           case 'e':
           case 'E':
              encrypt(filename,key);
              default:
              break;
              }
              op=getch();
              //see of tje user still wants to continue, 0x1b is escape key
                 if(op==0x1b)goto end;
                 goto begining;
                           end:
                           return 0;
}
/*
function filesize
arguments FILE *stream
a file stream object
returns size of the file as long
*/
long filesize(FILE *stream)
{
   long curpos, length;

   curpos = ftell(stream);
   fseek(stream, 0L, SEEK_END);
   length = ftell(stream);
   fseek(stream, curpos, SEEK_SET);
   return length;

}
/*
function encrypt:
arguments char *fname,char *key
  fname is filename to be encrypted,key is the encryption key
returns -1 if file fails to open, 0 if all goes well


*/
int encrypt(char *fname,char *key){

FILE *out;
         unsigned char *buf;
                         //open file and check if it exists
   if((out=fopen(fname,"rb+"))==NULL){textcolor(LIGHTRED);
   cprintf("error opening file!!! :(");cout<<endl; return -1;}
//   find the size of our file and convert the result to int
   int size=(int) filesize(out);
   //make sure we are at begining of file
   fseek(out, 0L, SEEK_SET);
   //make a buffer for file data
         buf=new char[size];
                          //read all the data of the file into buf
    for(int i=0;i<size;i++){
           buf[i]=fgetc(out);



}
//close our file stream
fclose(out);
                //remove our file from the system
remove(fname);
   //make a new file using our oringinal file name
     if((out=fopen(fname,"ab+"))==NULL){textcolor(LIGHTRED);
     cprintf("error opening file!!! :(");cout<<endl; return -1;}

        for(int i=0,j=0;i<size;i++,j++){
                          //when j equals length of the key make j=0
                           if(j==strlen(key)-1)j=0;
                           //xor each value of buf with each value of key
                           buf[i]=buf[i]^key[j];
                          //write the encrypted char's
                           fputc(buf[i],out);
                           }
                           textcolor(YELLOW);
                    cprintf("File encrypted :)");cout<<endl;
            return 1;
}
/*
function decrypt:
arguments char *fname,char *key
  fname is filename to be decrypted,key is the decryption key
returns -1 if file fails to open, 0 if all goes well
                 this function is basically a duplicate of encrypt

*/
int decrypt(char *fname,char *key){
FILE *out;
         unsigned char *buf;
     //open file and check if it exists
   if((out=fopen(fname,"rb+"))==NULL){textcolor(LIGHTRED);cprintf("error opening file!!! :(");cout<<endl; return -1;}
   //   find the size of our file and convert the result to int
   int size=(int) filesize(out);
   //make sure we are at begining of file
   fseek(out, 0L, SEEK_SET);
         //make a buffer for file data
         buf=new char[size];
                         //read all the data of the file into buf
    for(int i=0;i<size;i++){
           buf[i]=fgetc(out);



}
//close our file stream
fclose(out);
//remove our file from the system
remove(fname);
     //make a new file using our oringinal file name
     if((out=fopen(fname,"ab+"))==NULL){textcolor(LIGHTRED);
     cprintf("error opening file!!! :(");
     cout<<endl;
      return -1;}

        for(int i=0,j=0;i<size;i++,j++){
                                    //when j equals length of the key make j=0
                           if(j==strlen(key)-1)j=0;
                            //xor each value of buf with each value of key
                           buf[i]=buf[i]^key[j];
                                  //write the decrypted char's
                           fputc(buf[i],out);
                           }
                           textcolor(YELLOW);
                           cprintf("File decrypted :)",0x38); cout<<endl;
return 1;
}