959 строки
24 KiB
C
959 строки
24 KiB
C
/* mpicoder.c - Coder for the external representation of MPIs
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* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
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* 2008 Free Software Foundation, Inc.
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* Copyright (C) 2013, 2014 g10 Code GmbH
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*
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* This file is part of Libgcrypt.
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*
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* Libgcrypt is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* Libgcrypt is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include "mpi-internal.h"
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#include "g10lib.h"
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/* The maximum length we support in the functions converting an
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* external representation to an MPI. This limit is used to catch
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* programming errors and to avoid DoS due to insane long allocations.
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* The 16 MiB limit is actually ridiculous large but some of those PQC
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* algorithms use quite large keys and they might end up using MPIs
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* for that. */
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#define MAX_EXTERN_SCAN_BYTES (16*1024*1024)
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/* The maximum length (in bits) we support for OpenPGP MPIs. Note
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* that OpenPGP's MPI format uses only two bytes and thus would be
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* limited to 64k anyway. Note that this limit matches that used by
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* GnuPG. */
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#define MAX_EXTERN_MPI_BITS 16384
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/* Helper used to scan PGP style MPIs. Returns NULL on failure. */
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static gcry_mpi_t
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mpi_read_from_buffer (const unsigned char *buffer, unsigned *ret_nread,
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int secure)
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{
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int i, j;
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unsigned int nbits, nbytes, nlimbs, nread=0;
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mpi_limb_t a;
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gcry_mpi_t val = MPI_NULL;
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if ( *ret_nread < 2 )
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goto leave;
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nbits = buffer[0] << 8 | buffer[1];
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if ( nbits > MAX_EXTERN_MPI_BITS )
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{
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/* log_debug ("mpi too large (%u bits)\n", nbits); */
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goto leave;
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}
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buffer += 2;
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nread = 2;
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nbytes = (nbits+7) / 8;
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nlimbs = (nbytes+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB;
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val = secure? mpi_alloc_secure (nlimbs) : mpi_alloc (nlimbs);
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i = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
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i %= BYTES_PER_MPI_LIMB;
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j= val->nlimbs = nlimbs;
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val->sign = 0;
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for ( ; j > 0; j-- )
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{
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a = 0;
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for (; i < BYTES_PER_MPI_LIMB; i++ )
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{
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if ( ++nread > *ret_nread )
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{
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/* log_debug ("mpi larger than buffer"); */
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mpi_free (val);
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val = NULL;
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goto leave;
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}
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a <<= 8;
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a |= *buffer++;
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}
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i = 0;
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val->d[j-1] = a;
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}
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leave:
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*ret_nread = nread;
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return val;
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}
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/****************
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* Fill the mpi VAL from the hex string in STR.
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*/
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static int
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mpi_fromstr (gcry_mpi_t val, const char *str)
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{
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int sign = 0;
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int prepend_zero = 0;
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int i, j, c, c1, c2;
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unsigned int nbits, nbytes, nlimbs;
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mpi_limb_t a;
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if ( *str == '-' )
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{
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sign = 1;
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str++;
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}
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/* Skip optional hex prefix. */
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if ( *str == '0' && str[1] == 'x' )
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str += 2;
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nbits = strlen (str);
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if (nbits > MAX_EXTERN_SCAN_BYTES)
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{
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mpi_clear (val);
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return 1; /* Error. */
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}
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nbits *= 4;
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if ((nbits % 8))
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prepend_zero = 1;
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nbytes = (nbits+7) / 8;
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nlimbs = (nbytes+BYTES_PER_MPI_LIMB-1) / BYTES_PER_MPI_LIMB;
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if ( val->alloced < nlimbs )
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mpi_resize (val, nlimbs);
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i = BYTES_PER_MPI_LIMB - (nbytes % BYTES_PER_MPI_LIMB);
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i %= BYTES_PER_MPI_LIMB;
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j = val->nlimbs = nlimbs;
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val->sign = sign;
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for (; j > 0; j--)
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{
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a = 0;
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for (; i < BYTES_PER_MPI_LIMB; i++)
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{
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if (prepend_zero)
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{
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c1 = '0';
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prepend_zero = 0;
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}
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else
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c1 = *str++;
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if (!c1)
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{
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mpi_clear (val);
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return 1; /* Error. */
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}
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c2 = *str++;
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if (!c2)
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{
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mpi_clear (val);
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return 1; /* Error. */
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}
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if ( c1 >= '0' && c1 <= '9' )
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c = c1 - '0';
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else if ( c1 >= 'a' && c1 <= 'f' )
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c = c1 - 'a' + 10;
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else if ( c1 >= 'A' && c1 <= 'F' )
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c = c1 - 'A' + 10;
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else
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{
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mpi_clear (val);
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return 1; /* Error. */
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}
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c <<= 4;
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if ( c2 >= '0' && c2 <= '9' )
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c |= c2 - '0';
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else if( c2 >= 'a' && c2 <= 'f' )
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c |= c2 - 'a' + 10;
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else if( c2 >= 'A' && c2 <= 'F' )
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c |= c2 - 'A' + 10;
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else
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{
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mpi_clear(val);
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return 1; /* Error. */
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}
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a <<= 8;
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a |= c;
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}
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i = 0;
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val->d[j-1] = a;
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}
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return 0; /* Okay. */
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}
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/* Return an allocated buffer with the MPI (msb first). NBYTES
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receives the length of this buffer. If FILL_LE is not 0, the
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returned value is stored as little endian and right padded with
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zeroes so that the returned buffer has at least FILL_LE bytes.
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If EXTRAALLOC > 0 the returned buffer has these number of bytes
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extra allocated at the end; if EXTRAALLOC < 0 the returned buffer
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has the absolute value of EXTRAALLOC allocated at the begin of the
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buffer (the are not initialized) and the MPI is stored right after
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this. This feature is useful to allow the caller to prefix the
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returned value. EXTRAALLOC is _not_ included in the value stored
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at NBYTES.
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Caller must free the return string. This function returns an
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allocated buffer with NBYTES set to zero if the value of A is zero.
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If sign is not NULL, it will be set to the sign of the A. On error
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NULL is returned and ERRNO set appropriately. */
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static unsigned char *
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do_get_buffer (gcry_mpi_t a, unsigned int fill_le, int extraalloc,
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unsigned int *nbytes, int *sign, int force_secure)
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{
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unsigned char *p, *buffer, *retbuffer;
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unsigned int length, tmp;
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mpi_limb_t alimb;
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int i;
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size_t n, n2;
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if (sign)
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*sign = a->sign;
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*nbytes = a->nlimbs * BYTES_PER_MPI_LIMB;
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n = *nbytes? *nbytes:1; /* Allocate at least one byte. */
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if (n < fill_le)
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n = fill_le;
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if (extraalloc < 0)
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n2 = n + -extraalloc;
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else
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n2 = n + extraalloc;
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retbuffer = (force_secure || mpi_is_secure(a))? xtrymalloc_secure (n2)
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: xtrymalloc (n2);
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if (!retbuffer)
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return NULL;
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if (extraalloc < 0)
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buffer = retbuffer + -extraalloc;
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else
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buffer = retbuffer;
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p = buffer;
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for (i=a->nlimbs-1; i >= 0; i--)
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{
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alimb = a->d[i];
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#if BYTES_PER_MPI_LIMB == 4
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*p++ = alimb >> 24;
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*p++ = alimb >> 16;
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*p++ = alimb >> 8;
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*p++ = alimb ;
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#elif BYTES_PER_MPI_LIMB == 8
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*p++ = alimb >> 56;
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*p++ = alimb >> 48;
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*p++ = alimb >> 40;
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*p++ = alimb >> 32;
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*p++ = alimb >> 24;
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*p++ = alimb >> 16;
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*p++ = alimb >> 8;
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*p++ = alimb ;
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#else
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# error please implement for this limb size.
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#endif
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}
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if (fill_le)
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{
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length = *nbytes;
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/* Reverse buffer and pad with zeroes. */
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for (i=0; i < length/2; i++)
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{
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tmp = buffer[i];
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buffer[i] = buffer[length-1-i];
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buffer[length-1-i] = tmp;
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}
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/* Pad with zeroes. */
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for (p = buffer + length; length < fill_le; length++)
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*p++ = 0;
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*nbytes = length;
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return retbuffer;
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}
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/* This is sub-optimal but we need to do the shift operation because
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the caller has to free the returned buffer. */
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for (p=buffer; *nbytes && !*p; p++, --*nbytes)
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;
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if (p != buffer)
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memmove (buffer, p, *nbytes);
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return retbuffer;
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}
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byte *
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_gcry_mpi_get_buffer (gcry_mpi_t a, unsigned int fill_le,
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unsigned int *r_nbytes, int *sign)
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{
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if (mpi_get_flag (a, GCRYMPI_FLAG_OPAQUE))
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{
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unsigned int nbits;
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byte *p = _gcry_mpi_get_opaque_copy (a, &nbits);
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if (r_nbytes)
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*r_nbytes = (nbits+7)/8;
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return p;
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}
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else
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return do_get_buffer (a, fill_le, 0, r_nbytes, sign, 0);
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}
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byte *
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_gcry_mpi_get_buffer_extra (gcry_mpi_t a, unsigned int fill_le, int extraalloc,
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unsigned int *r_nbytes, int *sign)
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{
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return do_get_buffer (a, fill_le, extraalloc, r_nbytes, sign, 0);
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}
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byte *
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_gcry_mpi_get_secure_buffer (gcry_mpi_t a, unsigned int fill_le,
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unsigned int *r_nbytes, int *sign)
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{
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return do_get_buffer (a, fill_le, 0, r_nbytes, sign, 1);
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}
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/*
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* Use the NBYTES at BUFFER_ARG to update A. Set the sign of a to
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* SIGN.
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*/
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void
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_gcry_mpi_set_buffer (gcry_mpi_t a, const void *buffer_arg,
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unsigned int nbytes, int sign)
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{
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const unsigned char *buffer = (const unsigned char*)buffer_arg;
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const unsigned char *p;
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mpi_limb_t alimb;
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int nlimbs;
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int i;
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if (mpi_is_immutable (a))
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{
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mpi_immutable_failed ();
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return;
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}
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nlimbs = (nbytes + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB;
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RESIZE_IF_NEEDED(a, nlimbs);
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a->sign = sign;
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for (i=0, p = buffer+nbytes-1; p >= buffer+BYTES_PER_MPI_LIMB; )
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{
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#if BYTES_PER_MPI_LIMB == 4
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alimb = (mpi_limb_t)*p-- ;
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alimb |= (mpi_limb_t)*p-- << 8 ;
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alimb |= (mpi_limb_t)*p-- << 16 ;
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alimb |= (mpi_limb_t)*p-- << 24 ;
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#elif BYTES_PER_MPI_LIMB == 8
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alimb = (mpi_limb_t)*p-- ;
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alimb |= (mpi_limb_t)*p-- << 8 ;
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alimb |= (mpi_limb_t)*p-- << 16 ;
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alimb |= (mpi_limb_t)*p-- << 24 ;
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alimb |= (mpi_limb_t)*p-- << 32 ;
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alimb |= (mpi_limb_t)*p-- << 40 ;
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alimb |= (mpi_limb_t)*p-- << 48 ;
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alimb |= (mpi_limb_t)*p-- << 56 ;
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#else
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# error please implement for this limb size.
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#endif
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a->d[i++] = alimb;
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}
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if ( p >= buffer )
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{
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#if BYTES_PER_MPI_LIMB == 4
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alimb = (mpi_limb_t)*p--;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 8;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 16;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 24;
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#elif BYTES_PER_MPI_LIMB == 8
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alimb = (mpi_limb_t)*p--;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 8;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 16;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 24;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 32;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 40;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 48;
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if (p >= buffer)
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alimb |= (mpi_limb_t)*p-- << 56;
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#else
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# error please implement for this limb size.
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#endif
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a->d[i++] = alimb;
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}
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a->nlimbs = i;
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gcry_assert (i == nlimbs);
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}
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static void
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onecompl (gcry_mpi_t a)
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{
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mpi_ptr_t ap;
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mpi_size_t n;
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unsigned int i;
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unsigned int nbits;
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if (!a || mpi_is_immutable (a))
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{
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mpi_immutable_failed ();
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return;
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}
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nbits = mpi_get_nbits (a);
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mpi_normalize (a);
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ap = a->d;
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n = a->nlimbs;
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for( i = 0; i < n; i++ )
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ap[i] ^= (mpi_limb_t)(-1);
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a->sign = 0;
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mpi_clear_highbit (a, nbits-1);
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}
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/* Perform a two's complement operation on buffer P of size N bytes. */
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static void
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twocompl (unsigned char *p, unsigned int n)
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{
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int i;
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for (i=n-1; i >= 0 && !p[i]; i--)
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;
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if (i >= 0)
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{
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if ((p[i] & 0x01))
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p[i] = (((p[i] ^ 0xfe) | 0x01) & 0xff);
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else if ((p[i] & 0x02))
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p[i] = (((p[i] ^ 0xfc) | 0x02) & 0xfe);
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else if ((p[i] & 0x04))
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p[i] = (((p[i] ^ 0xf8) | 0x04) & 0xfc);
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else if ((p[i] & 0x08))
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p[i] = (((p[i] ^ 0xf0) | 0x08) & 0xf8);
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else if ((p[i] & 0x10))
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p[i] = (((p[i] ^ 0xe0) | 0x10) & 0xf0);
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else if ((p[i] & 0x20))
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p[i] = (((p[i] ^ 0xc0) | 0x20) & 0xe0);
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else if ((p[i] & 0x40))
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p[i] = (((p[i] ^ 0x80) | 0x40) & 0xc0);
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else
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p[i] = 0x80;
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for (i--; i >= 0; i--)
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p[i] ^= 0xff;
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}
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}
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/* Convert the external representation of an integer stored in BUFFER
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* with a length of BUFLEN into a newly create MPI returned in
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* RET_MPI. If NSCANNED is not NULL, it will receive the number of
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* bytes actually scanned after a successful operation. */
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gcry_err_code_t
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_gcry_mpi_scan (struct gcry_mpi **ret_mpi, enum gcry_mpi_format format,
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const void *buffer_arg, size_t buflen, size_t *nscanned)
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{
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const unsigned char *buffer = (const unsigned char*)buffer_arg;
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struct gcry_mpi *a = NULL;
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unsigned int len;
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int secure = (buffer && _gcry_is_secure (buffer));
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if (buflen > MAX_EXTERN_SCAN_BYTES)
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{
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if (nscanned)
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*nscanned = 0;
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return GPG_ERR_INV_OBJ;
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}
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if (format == GCRYMPI_FMT_SSH)
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len = 0;
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else
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len = buflen;
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if (format == GCRYMPI_FMT_STD)
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{
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const unsigned char *s = buffer;
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a = secure? mpi_alloc_secure ((len+BYTES_PER_MPI_LIMB-1)
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/BYTES_PER_MPI_LIMB)
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: mpi_alloc ((len+BYTES_PER_MPI_LIMB-1)/BYTES_PER_MPI_LIMB);
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if (len)
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{
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_gcry_mpi_set_buffer (a, s, len, 0);
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a->sign = !!(*s & 0x80);
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if (a->sign)
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{
|
|
onecompl (a);
|
|
mpi_add_ui (a, a, 1);
|
|
a->sign = 1;
|
|
}
|
|
}
|
|
if (ret_mpi)
|
|
{
|
|
mpi_normalize ( a );
|
|
*ret_mpi = a;
|
|
}
|
|
else
|
|
mpi_free(a);
|
|
if (nscanned)
|
|
*nscanned = len;
|
|
return 0;
|
|
}
|
|
else if (format == GCRYMPI_FMT_USG)
|
|
{
|
|
a = secure? mpi_alloc_secure ((len+BYTES_PER_MPI_LIMB-1)
|
|
/BYTES_PER_MPI_LIMB)
|
|
: mpi_alloc ((len+BYTES_PER_MPI_LIMB-1)/BYTES_PER_MPI_LIMB);
|
|
|
|
if (len)
|
|
_gcry_mpi_set_buffer (a, buffer, len, 0);
|
|
if (ret_mpi)
|
|
{
|
|
mpi_normalize ( a );
|
|
*ret_mpi = a;
|
|
}
|
|
else
|
|
mpi_free(a);
|
|
if (nscanned)
|
|
*nscanned = len;
|
|
return 0;
|
|
}
|
|
else if (format == GCRYMPI_FMT_PGP)
|
|
{
|
|
a = mpi_read_from_buffer (buffer, &len, secure);
|
|
if (nscanned)
|
|
*nscanned = len;
|
|
if (ret_mpi && a)
|
|
{
|
|
mpi_normalize (a);
|
|
*ret_mpi = a;
|
|
}
|
|
else if (a)
|
|
{
|
|
mpi_free(a);
|
|
a = NULL;
|
|
}
|
|
return a? 0 : GPG_ERR_INV_OBJ;
|
|
}
|
|
else if (format == GCRYMPI_FMT_SSH)
|
|
{
|
|
const unsigned char *s = buffer;
|
|
size_t n;
|
|
|
|
/* This test is not strictly necessary and an assert (!len)
|
|
would be sufficient. We keep this test in case we later
|
|
allow the BUFLEN argument to act as a sanitiy check. Same
|
|
below. */
|
|
if (len && len < 4)
|
|
return GPG_ERR_TOO_SHORT;
|
|
|
|
n = (s[0] << 24 | s[1] << 16 | s[2] << 8 | s[3]);
|
|
s += 4;
|
|
if (len)
|
|
len -= 4;
|
|
if (len && n > len)
|
|
return GPG_ERR_TOO_LARGE;
|
|
|
|
a = secure? mpi_alloc_secure ((n+BYTES_PER_MPI_LIMB-1)
|
|
/BYTES_PER_MPI_LIMB)
|
|
: mpi_alloc ((n+BYTES_PER_MPI_LIMB-1)/BYTES_PER_MPI_LIMB);
|
|
if (n)
|
|
{
|
|
_gcry_mpi_set_buffer( a, s, n, 0 );
|
|
a->sign = !!(*s & 0x80);
|
|
if (a->sign)
|
|
{
|
|
onecompl (a);
|
|
mpi_add_ui (a, a, 1);
|
|
a->sign = 1;
|
|
}
|
|
}
|
|
if (nscanned)
|
|
*nscanned = n+4;
|
|
if (ret_mpi)
|
|
{
|
|
mpi_normalize ( a );
|
|
*ret_mpi = a;
|
|
}
|
|
else
|
|
mpi_free(a);
|
|
return 0;
|
|
}
|
|
else if (format == GCRYMPI_FMT_HEX)
|
|
{
|
|
/* We can only handle C strings for now. */
|
|
if (buflen)
|
|
return GPG_ERR_INV_ARG;
|
|
|
|
a = secure? mpi_alloc_secure (0) : mpi_alloc(0);
|
|
if (mpi_fromstr (a, (const char *)buffer))
|
|
{
|
|
mpi_free (a);
|
|
return GPG_ERR_INV_OBJ;
|
|
}
|
|
if (ret_mpi)
|
|
{
|
|
mpi_normalize ( a );
|
|
*ret_mpi = a;
|
|
}
|
|
else
|
|
mpi_free(a);
|
|
if (nscanned)
|
|
*nscanned = strlen ((const char*)buffer);
|
|
return 0;
|
|
}
|
|
else
|
|
return GPG_ERR_INV_ARG;
|
|
}
|
|
|
|
|
|
/* Convert the big integer A into the external representation
|
|
described by FORMAT and store it in the provided BUFFER which has
|
|
been allocated by the user with a size of BUFLEN bytes. NWRITTEN
|
|
receives the actual length of the external representation unless it
|
|
has been passed as NULL. BUFFER may be NULL to query the required
|
|
length. */
|
|
gcry_err_code_t
|
|
_gcry_mpi_print (enum gcry_mpi_format format,
|
|
unsigned char *buffer, size_t buflen,
|
|
size_t *nwritten, struct gcry_mpi *a)
|
|
{
|
|
unsigned int nbits = mpi_get_nbits (a);
|
|
size_t len;
|
|
size_t dummy_nwritten;
|
|
int negative;
|
|
|
|
if (!nwritten)
|
|
nwritten = &dummy_nwritten;
|
|
|
|
/* Libgcrypt does no always care to set clear the sign if the value
|
|
is 0. For printing this is a bit of a surprise, in particular
|
|
because if some of the formats don't support negative numbers but
|
|
should be able to print a zero. Thus we need this extra test
|
|
for a negative number. */
|
|
if (a->sign && _gcry_mpi_cmp_ui (a, 0))
|
|
negative = 1;
|
|
else
|
|
negative = 0;
|
|
|
|
len = buflen;
|
|
*nwritten = 0;
|
|
if (format == GCRYMPI_FMT_STD)
|
|
{
|
|
unsigned char *tmp;
|
|
int extra = 0;
|
|
unsigned int n;
|
|
|
|
tmp = _gcry_mpi_get_buffer (a, 0, &n, NULL);
|
|
if (!tmp)
|
|
return gpg_err_code_from_syserror ();
|
|
|
|
if (negative)
|
|
{
|
|
twocompl (tmp, n);
|
|
if (!(*tmp & 0x80))
|
|
{
|
|
/* Need to extend the sign. */
|
|
n++;
|
|
extra = 2;
|
|
}
|
|
}
|
|
else if (n && (*tmp & 0x80))
|
|
{
|
|
/* Positive but the high bit of the returned buffer is set.
|
|
Thus we need to print an extra leading 0x00 so that the
|
|
output is interpreted as a positive number. */
|
|
n++;
|
|
extra = 1;
|
|
}
|
|
|
|
if (buffer && n > len)
|
|
{
|
|
/* The provided buffer is too short. */
|
|
xfree (tmp);
|
|
return GPG_ERR_TOO_SHORT;
|
|
}
|
|
if (buffer)
|
|
{
|
|
unsigned char *s = buffer;
|
|
|
|
if (extra == 1)
|
|
*s++ = 0;
|
|
else if (extra)
|
|
*s++ = 0xff;
|
|
memcpy (s, tmp, n-!!extra);
|
|
}
|
|
xfree (tmp);
|
|
*nwritten = n;
|
|
return 0;
|
|
}
|
|
else if (format == GCRYMPI_FMT_USG)
|
|
{
|
|
unsigned int n = (nbits + 7)/8;
|
|
|
|
/* Note: We ignore the sign for this format. */
|
|
/* FIXME: for performance reasons we should put this into
|
|
mpi_aprint because we can then use the buffer directly. */
|
|
|
|
if (buffer && n > len)
|
|
return GPG_ERR_TOO_SHORT;
|
|
if (buffer)
|
|
{
|
|
unsigned char *tmp;
|
|
|
|
tmp = _gcry_mpi_get_buffer (a, 0, &n, NULL);
|
|
if (!tmp)
|
|
return gpg_err_code_from_syserror ();
|
|
memcpy (buffer, tmp, n);
|
|
xfree (tmp);
|
|
}
|
|
*nwritten = n;
|
|
return 0;
|
|
}
|
|
else if (format == GCRYMPI_FMT_PGP)
|
|
{
|
|
unsigned int n = (nbits + 7)/8;
|
|
|
|
/* The PGP format can only handle unsigned integers. */
|
|
if (negative)
|
|
return GPG_ERR_INV_ARG;
|
|
|
|
if (buffer && n+2 > len)
|
|
return GPG_ERR_TOO_SHORT;
|
|
|
|
if (buffer)
|
|
{
|
|
unsigned char *tmp;
|
|
unsigned char *s = buffer;
|
|
|
|
s[0] = nbits >> 8;
|
|
s[1] = nbits;
|
|
|
|
tmp = _gcry_mpi_get_buffer (a, 0, &n, NULL);
|
|
if (!tmp)
|
|
return gpg_err_code_from_syserror ();
|
|
memcpy (s+2, tmp, n);
|
|
xfree (tmp);
|
|
}
|
|
*nwritten = n+2;
|
|
return 0;
|
|
}
|
|
else if (format == GCRYMPI_FMT_SSH)
|
|
{
|
|
unsigned char *tmp;
|
|
int extra = 0;
|
|
unsigned int n;
|
|
|
|
tmp = _gcry_mpi_get_buffer (a, 0, &n, NULL);
|
|
if (!tmp)
|
|
return gpg_err_code_from_syserror ();
|
|
|
|
if (negative)
|
|
{
|
|
twocompl (tmp, n);
|
|
if (!(*tmp & 0x80))
|
|
{
|
|
/* Need to extend the sign. */
|
|
n++;
|
|
extra = 2;
|
|
}
|
|
}
|
|
else if (n && (*tmp & 0x80))
|
|
{
|
|
n++;
|
|
extra=1;
|
|
}
|
|
|
|
if (buffer && n+4 > len)
|
|
{
|
|
xfree(tmp);
|
|
return GPG_ERR_TOO_SHORT;
|
|
}
|
|
|
|
if (buffer)
|
|
{
|
|
unsigned char *s = buffer;
|
|
|
|
*s++ = n >> 24;
|
|
*s++ = n >> 16;
|
|
*s++ = n >> 8;
|
|
*s++ = n;
|
|
if (extra == 1)
|
|
*s++ = 0;
|
|
else if (extra)
|
|
*s++ = 0xff;
|
|
memcpy (s, tmp, n-!!extra);
|
|
}
|
|
xfree (tmp);
|
|
*nwritten = 4+n;
|
|
return 0;
|
|
}
|
|
else if (format == GCRYMPI_FMT_HEX)
|
|
{
|
|
unsigned char *tmp;
|
|
int i;
|
|
int extra = 0;
|
|
unsigned int n = 0;
|
|
|
|
tmp = _gcry_mpi_get_buffer (a, 0, &n, NULL);
|
|
if (!tmp)
|
|
return gpg_err_code_from_syserror ();
|
|
if (!n || (*tmp & 0x80))
|
|
extra = 2;
|
|
|
|
if (buffer && 2*n + extra + negative + 1 > len)
|
|
{
|
|
xfree(tmp);
|
|
return GPG_ERR_TOO_SHORT;
|
|
}
|
|
if (buffer)
|
|
{
|
|
unsigned char *s = buffer;
|
|
|
|
if (negative)
|
|
*s++ = '-';
|
|
if (extra)
|
|
{
|
|
*s++ = '0';
|
|
*s++ = '0';
|
|
}
|
|
|
|
for (i=0; i < n; i++)
|
|
{
|
|
unsigned int c = tmp[i];
|
|
|
|
*s++ = (c >> 4) < 10? '0'+(c>>4) : 'A'+(c>>4)-10 ;
|
|
c &= 15;
|
|
*s++ = c < 10? '0'+c : 'A'+c-10 ;
|
|
}
|
|
*s++ = 0;
|
|
*nwritten = s - buffer;
|
|
}
|
|
else
|
|
{
|
|
*nwritten = 2*n + extra + negative + 1;
|
|
}
|
|
xfree (tmp);
|
|
return 0;
|
|
}
|
|
else
|
|
return GPG_ERR_INV_ARG;
|
|
}
|
|
|
|
|
|
/*
|
|
* Like gcry_mpi_print but this function allocates the buffer itself.
|
|
* The caller has to supply the address of a pointer. NWRITTEN may be
|
|
* NULL.
|
|
*/
|
|
gcry_err_code_t
|
|
_gcry_mpi_aprint (enum gcry_mpi_format format,
|
|
unsigned char **buffer, size_t *nwritten,
|
|
struct gcry_mpi *a)
|
|
{
|
|
size_t n;
|
|
gcry_err_code_t rc;
|
|
|
|
*buffer = NULL;
|
|
rc = _gcry_mpi_print (format, NULL, 0, &n, a);
|
|
if (rc)
|
|
return rc;
|
|
|
|
*buffer = mpi_is_secure(a) ? xtrymalloc_secure (n?n:1) : xtrymalloc (n?n:1);
|
|
if (!*buffer)
|
|
return gpg_err_code_from_syserror ();
|
|
/* If the returned buffer will have a length of 0, we nevertheless
|
|
allocated 1 byte (malloc needs it anyway) and store a 0. */
|
|
if (!n)
|
|
**buffer = 0;
|
|
rc = _gcry_mpi_print( format, *buffer, n, &n, a );
|
|
if (rc)
|
|
{
|
|
xfree (*buffer);
|
|
*buffer = NULL;
|
|
}
|
|
else if (nwritten)
|
|
*nwritten = n;
|
|
return rc;
|
|
}
|
|
|
|
|
|
/* Turn VALUE into an octet string and store it in an allocated buffer
|
|
at R_FRAME or - if R_RAME is NULL - copy it into the caller
|
|
provided buffer SPACE; either SPACE or R_FRAME may be used. If
|
|
SPACE if not NULL, the caller must provide a buffer of at least
|
|
NBYTES. If the resulting octet string is shorter than NBYTES pad
|
|
it to the left with zeroes. If VALUE does not fit into NBYTES
|
|
return an error code. */
|
|
gpg_err_code_t
|
|
_gcry_mpi_to_octet_string (unsigned char **r_frame, void *space,
|
|
gcry_mpi_t value, size_t nbytes)
|
|
{
|
|
gpg_err_code_t rc;
|
|
size_t nframe, noff, n;
|
|
unsigned char *frame;
|
|
|
|
if (!r_frame == !space)
|
|
return GPG_ERR_INV_ARG; /* Only one may be used. */
|
|
|
|
if (r_frame)
|
|
*r_frame = NULL;
|
|
|
|
rc = _gcry_mpi_print (GCRYMPI_FMT_USG, NULL, 0, &nframe, value);
|
|
if (rc)
|
|
return rc;
|
|
if (nframe > nbytes)
|
|
return GPG_ERR_TOO_LARGE; /* Value too long to fit into NBYTES. */
|
|
|
|
noff = (nframe < nbytes)? nbytes - nframe : 0;
|
|
n = nframe + noff;
|
|
if (space)
|
|
frame = space;
|
|
else
|
|
{
|
|
frame = mpi_is_secure (value)? xtrymalloc_secure (n) : xtrymalloc (n);
|
|
if (!frame)
|
|
{
|
|
rc = gpg_err_code_from_syserror ();
|
|
return rc;
|
|
}
|
|
}
|
|
if (noff)
|
|
memset (frame, 0, noff);
|
|
nframe += noff;
|
|
rc = _gcry_mpi_print (GCRYMPI_FMT_USG, frame+noff, nframe-noff, NULL, value);
|
|
if (rc)
|
|
{
|
|
xfree (frame);
|
|
return rc;
|
|
}
|
|
|
|
if (r_frame)
|
|
*r_frame = frame;
|
|
return 0;
|
|
}
|