pad.h

/*
    This file is part of Pretty Curved Privacy (pcp1).

    Copyright (C) 2013 T.Linden.

    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/>.

    You can contact me by mail: <tlinden AT cpan DOT org>.
*/


#ifndef _HAVE_PCP_ZPADDING
#define _HAVE_PCP_ZPADDING

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdlib.h>
#include <limits.h>

#include "mem.h"

#ifdef DEBUG
#define ZPADCHAR 48
#else
#define ZPADCHAR 0
#endif

/*  prepends a binary stream with a number of */
/*  \0's as required by the secret_box and */
/*  secret_box_open functions of libsodium. */
/*  */
/*  parameters: */
/*  */
/*  padded:    destination array (ref) */
/*  unpadded:  source array without padding */
/*  padlen:    length of padding */
/*  unpadlen:  length of source array */
/*  */
/*  turns "efa5" into "00000000efa5" with padlen 8 */
/*  */
/*  if DEBUG is set, destination will be padded with */
/*  the character '0', NOT the integer 0. */
/*  */
/*  allocates memory for padded and it is up to the */
/*  user to free it after use. */
/*  */
/*  sample call: */
/*  */
/*  char unpadded[] = {0xef, 0xa5}; */
/*  unsigned char *padded; */
/*  pcp_pad_prepend(&padded, unpadded, 8, 2); */
/*  */
/*  the result, padded, would be 10 bytes long, 8 */
/*  bytes for the leading zeros and 2 for the content */
/*  of the original unpadded. */
void pcp_pad_prepend(unsigned char **padded, unsigned char *unpadded,
                 size_t padlen, size_t unpadlen);

/*  removes zero's of a binary stream, which is */
/*  the reverse of pcp_pad_prepend(). */
/*  */
/*  parameters: */
/*   */
/*  unpadded:   destination array (ref), with padding removed */
/*  padded:     source array with padding */
/*  padlen:     length of padding */
/*  unpadlen:   length of source array */
/*  */
/*  turns "00000000efa5" into "efa5" with padlen 8 */
/*  */
/*  allocates memory for unpadded and it is up to the */
/*  user to free it after use. */
/*  */
/*  sample call: */
/*  */
/*  char padded[] = {0x0, 0x0, 0x0, 0x0, 0xef, 0xa5}; */
/*  unsigned char *unpadded; */
/*  pcp_pad_remove(unpadded, padded, 4, 2); */
/*  */
/*  the result, unpadded would be 2 bytes long containing */
/*  only the 2 bytes we want to have with zeros removed. */
void pcp_pad_remove(unsigned char **unpadded, unsigned char *padded,
                size_t padlen, size_t unpadlen);


#endif /*  _HAVE_PCP_ZPADDING */