crypto/asn1/x_bignum.c

/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.] */

#include <openssl/asn1.h>

#include <openssl/asn1t.h>
#include <openssl/bn.h>


/* Custom primitive type for BIGNUM handling. This reads in an ASN1_INTEGER as a
 * BIGNUM directly. Currently it ignores the sign which isn't a problem since all
 * BIGNUMs used are non negative and anything that looks negative is normally due
 * to an encoding error.
 */

#define BN_SENSITIVE	1

static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it);
static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it);

static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype, const ASN1_ITEM *it);
static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len, int utype, char *free_cont, const ASN1_ITEM *it);

static const ASN1_PRIMITIVE_FUNCS bignum_pf = {
	NULL, 0,
	bn_new,
	bn_free,
	0,
	bn_c2i,
	bn_i2c,
	NULL /* prim_print */,
};

ASN1_ITEM_start(BIGNUM)
	ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &bignum_pf, 0, "BIGNUM"
ASN1_ITEM_end(BIGNUM)

ASN1_ITEM_start(CBIGNUM)
	ASN1_ITYPE_PRIMITIVE, V_ASN1_INTEGER, NULL, 0, &bignum_pf, BN_SENSITIVE, "BIGNUM"
ASN1_ITEM_end(CBIGNUM)

static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
{
	*pval = (ASN1_VALUE *)BN_new();
	if(*pval) return 1;
	else return 0;
}

static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
{
	if(!*pval) return;
	if(it->size & BN_SENSITIVE) BN_clear_free((BIGNUM *)*pval);
	else BN_free((BIGNUM *)*pval);
	*pval = NULL;
}

static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype, const ASN1_ITEM *it)
{
	BIGNUM *bn;
	int pad;
	if(!*pval) return -1;
	bn = (BIGNUM *)*pval;
	/* If MSB set in an octet we need a padding byte */
	if(BN_num_bits(bn) & 0x7) pad = 0;
	else pad = 1;
	if(cont) {
		if(pad) *cont++ = 0;
		BN_bn2bin(bn, cont);
	}
	return pad + BN_num_bytes(bn);
}

static int bn_c2i(ASN1_VALUE **pval, const unsigned char *cont, int len,
		  int utype, char *free_cont, const ASN1_ITEM *it)
{
	BIGNUM *bn;
	if(!*pval)
		{
		if (!bn_new(pval, it))
			{
			return 0;
			}
		}
	bn  = (BIGNUM *)*pval;
	if(!BN_bin2bn(cont, len, bn)) {
		bn_free(pval, it);
		return 0;
	}
	return 1;
}