crypto_mpi.c

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/*
     This file is part of GNUnet.
     Copyright (C) 2012, 2013 GNUnet e.V.
 
     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.
 
     GNUnet 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
     Affero General Public License for more details.
 
     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
     SPDX-License-Identifier: AGPL3.0-or-later
 */
 
#include "platform.h"
#include <gcrypt.h>
#include "gnunet_util_lib.h"
 
 
#define LOG(kind, ...) GNUNET_log_from (kind, "util-crypto-mpi", __VA_ARGS__)
 
#define LOG_GCRY(level, cmd, rc) do { LOG (level, _ ( \
                                             "`%s' failed at %s:%d with error: %s\n"), \
                                           cmd, __FILE__, __LINE__, \
                                           gcry_strerror (rc)); } while (0)
 
 
static void
adjust (void *buf,
        size_t size,
        size_t target)
{
  char *p = buf;
 
  if (size < target)
  {
    memmove (&p[target - size], buf, size);
    memset (buf, 0, target - size);
  }
}
 
 
void
GNUNET_CRYPTO_mpi_print_unsigned (void *buf,
                                  size_t size,
                                  gcry_mpi_t val)
{
  size_t rsize;
  int rc;
 
  if (gcry_mpi_get_flag (val, GCRYMPI_FLAG_OPAQUE))
  {
    /* Store opaque MPIs left aligned into the buffer.  */
    unsigned int nbits;
    const void *p;
 
    p = gcry_mpi_get_opaque (val, &nbits);
    GNUNET_assert (p);
    rsize = (nbits + 7) / 8;
    if (rsize > size)
      rsize = size;
    GNUNET_memcpy (buf, p, rsize);
    if (rsize < size)
      memset (buf + rsize, 0, size - rsize);
  }
  else
  {
    /* Store regular MPIs as unsigned integers right aligned into
       the buffer.  */
    rsize = size;
    if (0 !=
        (rc = gcry_mpi_print (GCRYMPI_FMT_USG,
                              buf,
                              rsize, &rsize,
                              val)))
    {
      LOG_GCRY (GNUNET_ERROR_TYPE_ERROR,
                "gcry_mpi_print",
                rc);
      GNUNET_assert (0);
    }
    adjust (buf, rsize, size);
  }
}
 
 
void
GNUNET_CRYPTO_mpi_scan_unsigned (gcry_mpi_t *result,
                                 const void *data,
                                 size_t size)
{
  int rc;
 
  if (0 != (rc = gcry_mpi_scan (result,
                                GCRYMPI_FMT_USG,
                                data, size, &size)))
  {
    LOG_GCRY (GNUNET_ERROR_TYPE_ERROR,
              "gcry_mpi_scan",
              rc);
    GNUNET_assert (0);
  }
}
 
 
/* end of crypto_mpi.c */