D-LOK - XOR encryption / decryption program

D-LOK is an XOR based encryption / decryption command line tool written in C. This utility will encrypt / decrypt sensitive data using XOR. D-LOK can successfully encrypt / decrypt file types such as: .txt, .doc, .gif, .jpg, .log, .zip, .wmv, .rtf etc... D-LOK also overwrites original data before deleting it if desired.

#include <stdio.h>

/*
     Program: D-LOK
     Type: Command line XOR encryption utility
     Coder: Dave Lauderdale
     Published at: www.digi-dl.com
     Language: C
     Assembly: WIN - Borlands C++ command line compiler v5.5.1
               LINUX - gcc v 3.3.3
*/

// How much data to overwrite, 1E.5 = roughly 1 megabyte, 2.E5 will = roughly 2 megabytes etc...
#define overWrite 1.E5

int usage(void);
int usage()
{
     printf("\nD-LOK v1.2 - XOR encryption program by Dave Lauderdale.  \n");
     printf("\n=======================USAGE========================== \n\n");
     printf("Win32 -  C:\\>D-LOK <inFile> <outFile> <key> [-d]           \n");
     printf("Linux -  [foo@bar]$ ./D-LOK <inFile> <outFile> <key> [-d]\n\n");  
     printf("Optional -d switch will overwrite and delete original file.\n"); 
     exit(0);
}

int main(int argc, char *argv[])
{
     FILE *originalData, *encryptedData;
     int byte, character, x, i, argComp;
     char delSwitch[] = "-d";

// If user enters wrong number of args display usage
     if(argc != 4 && argc != 5) usage();

// Try to open original file for reading : display error if there is a problem
     if((originalData = fopen(argv[1], "rb")) == NULL)
     {
          printf("\nError opening %s\n\n", argv[1]);
          exit(0);
     }

// Try to open/create new encrypted file for writing: display error if there is a problem
     if((encryptedData = fopen(argv[2], "wb")) == NULL)
     {
          printf("\nError opening %s\n\n", argv[2]);
          exit(0);
     }

// Loop through file character by character until the end
     while((character = getc(originalData)) != EOF)
     {
          // encrypt each character using XOR and your key value
          character = character ^ *argv[3];
          byte++; putc(character, encryptedData);
     }
     fclose(originalData); fclose(encryptedData);

// If user adds 5th arg (possible -d switch)
     if(argc == 5) 
     {
        // compare the arg value with hardcoded value (-d)
    	argComp = strcmp(delSwitch,argv[4]);

// If user entered -d switch then overwrite original file...
     	if(argComp==0)
     	{
                // Overwrite file 7 times : change this if you want
         	for(x=0;x<7;x++)
         	{
                        // open original file for overwrite process
              		originalData = fopen(argv[1], "wb");

//Overwrite 1.E5 times
              		for(i=0;i<overWrite;i++)
              		{
                                //Overwrite using multiple character sets
                   		if(x < 3) fprintf(originalData, "-*-¤rå§¤Ð-°DL°-*-");
                   		if(x == 3) fprintf(originalData,"01000100~01001100");
                   		if(x > 3) fprintf(originalData, "-*-°DL°-¤rå§¤Ð-*-");
              		}
              		fclose(originalData);
         	}
                //and delete original file
        	remove(argv[1]); return 0;
    	 }
   }
}

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