encrypt.c

/*
 * Copyright (C) 2013 Sarzyniec Luc <contact@olbat.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * see the COPYING file for more informations */

#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define PRINT_FORMAT "\\x%.2x"
#define BUFF_SIZE 1024
#define PRINT_DISPLAY(F,C) __extension__ \
({ \
	printf(F,C); \
	fflush(stdout); \
})

static int fd;

int main(int argc, char **argv)
{
	char *key,*ptr;
	unsigned char c;
	unsigned int i;
	size_t len;

	if (argc < 2)
	{
		printf("usage: %s <file> [<key>|-]\n",*argv);
                return 1;
	}

	ptr = 0;

	if ((argc > 2) && (strcmp(argv[2],"-")))
	{
		key = argv[2];
		len = strlen(key);
	}
	else
	{
		size_t tmp;

		key = malloc(BUFF_SIZE);

		len = 0;
		ptr = key;
		while ((tmp = read(STDIN_FILENO,ptr,BUFF_SIZE)) > 0)
		{
			len += tmp;
			if (tmp == BUFF_SIZE)
				key = realloc(key,len+BUFF_SIZE);
			ptr = key + len;
		}
	}

	fd = open(argv[1], O_RDONLY);
	for (i=0;read(fd,&c,sizeof(c)) > 0;i++)
		PRINT_DISPLAY(PRINT_FORMAT,c^key[(i + key[i%len])%len]);
	close(fd);

	if (ptr)
		free(key);

	puts("");
        return 0;
}