ec_pmeth.c

/* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL
 * project 2006.
 */
/* ====================================================================
 * Copyright (c) 2006 The OpenSSL Project.  All rights reserved.
 *
 * 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 above 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 acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include "cryptlib.h"
#include <openssl/asn1t.h>
#include <openssl/x509.h>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/evp.h>
#include "evp_locl.h"

/* EC pkey context structure */

typedef struct
	{
	/* Key and paramgen group */
	EC_GROUP *gen_group;
	/* message digest */
	const EVP_MD *md;
	} EC_PKEY_CTX;

static int pkey_ec_init(EVP_PKEY_CTX *ctx)
	{
	EC_PKEY_CTX *dctx;
	dctx = OPENSSL_malloc(sizeof(EC_PKEY_CTX));
	if (!dctx)
		return 0;
	dctx->gen_group = NULL;
	dctx->md = NULL;

	ctx->data = dctx;

	return 1;
	}

static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
	{
	EC_PKEY_CTX *dctx = ctx->data;
	if (dctx)
		{
		if (dctx->gen_group)
			EC_GROUP_free(dctx->gen_group);
		OPENSSL_free(dctx);
		}
	}

static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, int *siglen,
					const unsigned char *tbs, int tbslen)
	{
	int ret, type;
	unsigned int sltmp;
	EC_PKEY_CTX *dctx = ctx->data;
	EC_KEY *ec = ctx->pkey->pkey.ec;

	if (!sig)
		{
		*siglen = ECDSA_size(ec);
		return 1;
		}
	else if(*siglen < ECDSA_size(ec))
		{
		ECerr(EC_F_PKEY_EC_SIGN, EC_R_BUFFER_TOO_SMALL);
		return 0;
		}

	if (dctx->md)
		type = EVP_MD_type(dctx->md);
	else
		type = NID_sha1;


	ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);

	if (ret < 0)
		return ret;
	*siglen = sltmp;
	return 1;
	}

static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
					const unsigned char *sig, int siglen,
					const unsigned char *tbs, int tbslen)
	{
	int ret, type;
	EC_PKEY_CTX *dctx = ctx->data;
	EC_KEY *ec = ctx->pkey->pkey.ec;

	if (dctx->md)
		type = EVP_MD_type(dctx->md);
	else
		type = NID_sha1;

	ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);

	return ret;
	}

static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, int *keylen)
	{
	int ret;
	size_t outlen;
	const EC_POINT *pubkey = NULL;
	if (!ctx->pkey || !ctx->peerkey)
		{
		ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
		return 0;
		}

	if (!key)
		{
		const EC_GROUP *group;
		group = EC_KEY_get0_group(ctx->pkey->pkey.ec);
		*keylen = (EC_GROUP_get_degree(group) + 7)/8;
		return 1;
		}

	pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);

	/* NB: unlike PKS#3 DH, if *outlen is less than maximum size this is
	 * not an error, the result is truncated.
	 */

	outlen = *keylen;
		
	ret = ECDH_compute_key(key, outlen, pubkey, ctx->pkey->pkey.ec, 0);
	if (ret < 0)
		return ret;
	*keylen = ret;
	return 1;
	}

static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
	{
	EC_PKEY_CTX *dctx = ctx->data;
	EC_GROUP *group;
	switch (type)
		{
		case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
		group = EC_GROUP_new_by_curve_name(p1);
		if (group == NULL)
			{
			ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_CURVE);
			return 0;
			}
		if (dctx->gen_group)
			EC_GROUP_free(dctx->gen_group);
		dctx->gen_group = group;
		return 1;

		case EVP_PKEY_CTRL_MD:
		if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1)
			{
			ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_DIGEST_TYPE);
			return 0;
			}
		dctx->md = p2;
		return 1;

		case EVP_PKEY_CTRL_PEER_KEY:
		/* Default behaviour is OK */
		return 1;

		default:
		return -2;

		}
	}
			
static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
			const char *type, const char *value)
	{
	if (!strcmp(type, "ec_paramgen_curve"))
		{
		int nid;
		nid = OBJ_sn2nid(value);
		if (nid == NID_undef)
			nid = OBJ_ln2nid(value);
		if (nid == NID_undef)
			{
			ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_CURVE);
			return 0;
			}
		return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
		}
	return -2;
	}

static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
	{
	EC_KEY *ec = NULL;
	EC_PKEY_CTX *dctx = ctx->data;
	int ret = 0;
	if (dctx->gen_group == NULL)
		{
		ECerr(EC_F_PKEY_EC_PARAMGEN, EC_R_NO_PARAMETERS_SET);
		return 0;
		}
	ec = EC_KEY_new();
	if (!ec)
		return 0;
	ret = EC_KEY_set_group(ec, dctx->gen_group);
	if (ret)
		EVP_PKEY_assign_EC_KEY(pkey, ec);
	else
		EC_KEY_free(ec);
	return ret;
	}

static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
	{
	EC_KEY *ec = NULL;
	if (ctx->pkey == NULL)
		{
		ECerr(EC_F_PKEY_EC_KEYGEN, EC_R_NO_PARAMETERS_SET);
		return 0;
		}
	ec = EC_KEY_new();
	if (!ec)
		return 0;
	EVP_PKEY_assign_EC_KEY(pkey, ec);
	/* Note: if error return, pkey is freed by parent routine */
	if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
		return 0;
	return EC_KEY_generate_key(pkey->pkey.ec);
	}

const EVP_PKEY_METHOD ec_pkey_meth = 
	{
	EVP_PKEY_EC,
	0,
	pkey_ec_init,
	pkey_ec_cleanup,

	0,
	pkey_ec_paramgen,

	0,
	pkey_ec_keygen,

	0,
	pkey_ec_sign,

	0,
	pkey_ec_verify,

	0,0,

	0,0,0,0,

	0,0,

	0,0,

	0,
	pkey_ec_derive,

	pkey_ec_ctrl,
	pkey_ec_ctrl_str

	};