/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 *
 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org
 */
#include "tomcrypt.h"
#include <ncr-int.h>

/**
   @file dsa_export.c
   DSA implementation, export key, Tom St Denis
*/

#ifdef LTC_MDSA

/**
  Export a DSA key to a binary packet
  @param out    [out] Where to store the packet
  @param outlen [in/out] The max size and resulting size of the packet
  @param type   The type of key to export (PK_PRIVATE or PK_PUBLIC)
  @param key    The key to export
  @return CRYPT_OK if successful
*/
int dsa_export(unsigned char *out, unsigned long *outlen, int type,
	       dsa_key * key)
{
	unsigned long zero = 0;
	int err;
	const struct algo_properties_st *algo = _ncr_algo_to_properties(NCR_ALG_DSA);

	LTC_ARGCHK(out != NULL);
	LTC_ARGCHK(outlen != NULL);
	LTC_ARGCHK(key != NULL);

	if (algo == NULL) {
		return CRYPT_INVALID_ARG;
	}

	/* can we store the static header?  */
	if (type == PK_PRIVATE && key->type != PK_PRIVATE) {
		return CRYPT_PK_TYPE_MISMATCH;
	}

	if (type != PK_PUBLIC && type != PK_PRIVATE) {
		return CRYPT_INVALID_ARG;
	}

	/* This encoding is different from the one in original
	 * libtomcrypt. It uses a compatible encoding with gnutls
	 * and openssl 
	 */
	if (type == PK_PRIVATE) {
		return der_encode_sequence_multi(out, outlen,
						 LTC_ASN1_SHORT_INTEGER, 1UL,
						 &zero, LTC_ASN1_INTEGER, 1UL,
						 &key->p, LTC_ASN1_INTEGER, 1UL,
						 &key->q, LTC_ASN1_INTEGER, 1UL,
						 &key->g, LTC_ASN1_INTEGER, 1UL,
						 &key->y, LTC_ASN1_INTEGER, 1UL,
						 &key->x, LTC_ASN1_EOL, 0UL,
						 NULL);
	} else {
		unsigned long tmplen = (mp_count_bits(&key->y) / 8) + 8;
		unsigned char *tmp = XMALLOC(tmplen);
		ltc_asn1_list int_list[3];

		if (tmp == NULL) {
			return CRYPT_MEM;
		}

		err = der_encode_integer(&key->y, tmp, &tmplen);
		if (err != CRYPT_OK) {
			goto error;
		}

		int_list[0].data = &key->p;
		int_list[0].size = 1UL;
		int_list[0].type = LTC_ASN1_INTEGER;
		int_list[1].data = &key->q;
		int_list[1].size = 1UL;
		int_list[1].type = LTC_ASN1_INTEGER;
		int_list[2].data = &key->g;
		int_list[2].size = 1UL;
		int_list[2].type = LTC_ASN1_INTEGER;

		err = der_encode_subject_public_key_info(out, outlen,
							 algo, tmp, tmplen,
							 LTC_ASN1_SEQUENCE,
							 int_list,
							 sizeof(int_list) /
							 sizeof(int_list[0]));

error:
		XFREE(tmp);
		return err;
	}
}

#endif

/* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_export.c,v $ */
/* $Revision: 1.10 $ */
/* $Date: 2007/05/12 14:32:35 $ */