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/* some multiprecision utilities
* Copyright (C) 1998-2001 D. Hugh Redelmeier.
*
* 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 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* 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.
*
* RCSID $Id$
*/
#include <freeswan.h>
#include <utils.h>
#include <asn1/asn1.h>
#include "constants.h"
#include "defs.h"
#include "mp_defs.h"
#include "log.h"
/* Convert MP_INT to network form (binary octets, big-endian).
* We do the malloc; caller must eventually do free.
*/
chunk_t
mpz_to_n(const MP_INT *mp, size_t bytes)
{
chunk_t r;
MP_INT temp1, temp2;
int i;
r.len = bytes;
r.ptr = malloc(r.len);
mpz_init(&temp1);
mpz_init(&temp2);
mpz_set(&temp1, mp);
for (i = r.len-1; i >= 0; i--)
{
r.ptr[i] = mpz_mdivmod_ui(&temp2, NULL, &temp1, 1 << BITS_PER_BYTE);
mpz_set(&temp1, &temp2);
}
passert(mpz_sgn(&temp1) == 0); /* we must have done all the bits */
mpz_clear(&temp1);
mpz_clear(&temp2);
return r;
}
/* Convert network form (binary bytes, big-endian) to MP_INT.
* The *mp must not be previously mpz_inited.
*/
void
n_to_mpz(MP_INT *mp, const u_char *nbytes, size_t nlen)
{
size_t i;
mpz_init_set_ui(mp, 0);
for (i = 0; i != nlen; i++)
{
mpz_mul_ui(mp, mp, 1 << BITS_PER_BYTE);
mpz_add_ui(mp, mp, nbytes[i]);
}
}
/*
* convert a MP integer into a DER coded ASN.1 object
*/
chunk_t
asn1_integer_from_mpz(const mpz_t value)
{
size_t bits = mpz_sizeinbase(value, 2); /* size in bits */
size_t size = 1 + bits / BITS_PER_BYTE; /* size in bytes */
chunk_t n = mpz_to_n(value, size);
return asn1_wrap(ASN1_INTEGER, "m", n);
}
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