ec_pmeth.c

/* Written by Dr Stephen N Henson (steve@openssl.org) 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 "ec_lcl.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;
	/* Duplicate key if custom cofactor needed */
	EC_KEY *co_key;
	/* Cofactor mode */
	signed char cofactor_mode;
	/* KDF (if any) to use for ECDH */
	char kdf_type;
	/* Message digest to use for key derivation */
	const EVP_MD *kdf_md;
	/* User key material */
	unsigned char *kdf_ukm;
	size_t kdf_ukmlen;
	/* KDF output length */
	size_t kdf_outlen;

	} 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;

	dctx->cofactor_mode = -1;
	dctx->co_key = NULL;
	dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
	dctx->kdf_md = NULL;
	dctx->kdf_outlen = 0;
	dctx->kdf_ukm = NULL;
	dctx->kdf_ukmlen = 0;

	ctx->data = dctx;

	return 1;
	}

static int pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
	{
	EC_PKEY_CTX *dctx, *sctx;
	if (!pkey_ec_init(dst))
		return 0;
       	sctx = src->data;
	dctx = dst->data;
	if (sctx->gen_group)
		{
		dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
		if (!dctx->gen_group)
			return 0;
		}
	dctx->md = sctx->md;

	if (sctx->co_key)
		{
		dctx->co_key = EC_KEY_dup(sctx->co_key);
		if (!dctx->co_key)
			return 0;
		}
	dctx->kdf_type = sctx->kdf_type;
	dctx->kdf_md = sctx->kdf_md;
	dctx->kdf_outlen = sctx->kdf_outlen;
	if (sctx->kdf_ukm)
		{
		dctx->kdf_ukm = BUF_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
		if (!dctx->kdf_ukm)
			return 0;
		}
	else
		dctx->kdf_ukm = NULL;
	dctx->kdf_ukmlen = sctx->kdf_ukmlen;
	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);
		if (dctx->co_key)
			EC_KEY_free(dctx->co_key);
		if (dctx->kdf_ukm)
			OPENSSL_free(dctx->kdf_ukm);
		OPENSSL_free(dctx);
		}
	}

static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
					const unsigned char *tbs, size_t 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 < (size_t)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 = (size_t)sltmp;
	return 1;
	}

static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
					const unsigned char *sig, size_t siglen,
					const unsigned char *tbs, size_t 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, size_t *keylen)
	{
	int ret;
	size_t outlen;
	const EC_POINT *pubkey = NULL;
	EC_KEY *eckey;
	EC_PKEY_CTX *dctx = ctx->data;
	if (!ctx->pkey || !ctx->peerkey)
		{
		ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
		return 0;
		}

	eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;

	if (!key)
		{
		const EC_GROUP *group;
		group = EC_KEY_get0_group(eckey);
		*keylen = (EC_GROUP_get_degree(group) + 7)/8;
		return 1;
		}
	pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);

	/* NB: unlike PKCS#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, eckey, 0);
	if (ret <= 0)
		return 0;
	*keylen = ret;
	return 1;
	}

static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
				unsigned char *key, size_t *keylen)
	{
	EC_PKEY_CTX *dctx = ctx->data;
	unsigned char *ktmp = NULL;
	size_t ktmplen;
	int rv = 0;
	if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
		return pkey_ec_derive(ctx, key, keylen);
	if (!key)
		{
		*keylen = dctx->kdf_outlen;
		return 1;
		}
	if (*keylen != dctx->kdf_outlen)
		return 0;
	if (!pkey_ec_derive(ctx, NULL, &ktmplen))
		return 0;
	ktmp = OPENSSL_malloc(ktmplen);
	if (!ktmp)
		return 0;
	if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
		goto err;
	/* Do KDF stuff */
	if (!ECDH_KDF_X9_62(key, *keylen, ktmp, ktmplen, 
				dctx->kdf_ukm, dctx->kdf_ukmlen,
				dctx->kdf_md))
		goto err;
	rv = 1;

	err:
	if (ktmp)
		{
		OPENSSL_cleanse(ktmp, ktmplen);
		OPENSSL_free(ktmp);
		}
	return rv;
	}

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_EC_PARAM_ENC:
		if (!dctx->gen_group)
			{
			ECerr(EC_F_PKEY_EC_CTRL, EC_R_NO_PARAMETERS_SET);
			return 0;
			}
		EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
		return 1;

		case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
		if (p1 == -2)
			{
			if (dctx->cofactor_mode != -1)
				return dctx->cofactor_mode;
			else
				{
				EC_KEY *ec_key = ctx->pkey->pkey.ec;
				return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
				}
			}
		else if (p1 < -1 || p1 > 1)
			return -2;
		dctx->cofactor_mode = p1;
		if (p1 != -1)
			{
			EC_KEY *ec_key = ctx->pkey->pkey.ec;
			if (!ec_key->group)
				return -2;
			/* If cofactor is 1 cofactor mode does nothing */
			if (BN_is_one(ec_key->group->cofactor))
				return 1;
			if (!dctx->co_key)
				{
				dctx->co_key = EC_KEY_dup(ec_key);
				if (!dctx->co_key)
					return 0;
				}
			if (p1)
				EC_KEY_set_flags(dctx->co_key,
							EC_FLAG_COFACTOR_ECDH);
			else
				EC_KEY_clear_flags(dctx->co_key,
							EC_FLAG_COFACTOR_ECDH);
			}
		else if (dctx->co_key)
			{
			EC_KEY_free(dctx->co_key);
			dctx->co_key = NULL;
			}
		return 1;

		case EVP_PKEY_CTRL_EC_KDF_TYPE:
		if (p1 == -2)
			return dctx->kdf_type;
		if (p1 != EVP_PKEY_ECDH_KDF_NONE &&
		    p1 != EVP_PKEY_ECDH_KDF_X9_62)
			return -2;
		dctx->kdf_type = p1;
		return 1;

		case EVP_PKEY_CTRL_EC_KDF_MD:
		dctx->kdf_md = p2;
		return 1;

		case EVP_PKEY_CTRL_GET_EC_KDF_MD:
		*(const EVP_MD **)p2 = dctx->kdf_md;
		return 1;

		case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
		if (p1 <= 0)
			return -2;
		dctx->kdf_outlen = (size_t)p1;
		return 1;

		case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
		*(int *)p2 = dctx->kdf_outlen;
		return 1;

		case EVP_PKEY_CTRL_EC_KDF_UKM:
		if (dctx->kdf_ukm)
			OPENSSL_free(dctx->kdf_ukm);
		dctx->kdf_ukm = p2;
		if (p2)
			dctx->kdf_ukmlen = p1;
		else
			dctx->kdf_ukmlen = 0;
		return 1;

		case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
		*(unsigned char **)p2 = dctx->kdf_ukm;
		return dctx->kdf_ukmlen;

		case EVP_PKEY_CTRL_MD:
		if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
		    EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
		    EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
		    EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
		    EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
		    EVP_MD_type((const EVP_MD *)p2) != NID_sha512)
			{
			ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_DIGEST_TYPE);
			return 0;
			}
		dctx->md = p2;
		return 1;

		case EVP_PKEY_CTRL_GET_MD:
		*(const EVP_MD **)p2 = dctx->md;
		return 1;

		case EVP_PKEY_CTRL_PEER_KEY:
		/* Default behaviour is OK */
		case EVP_PKEY_CTRL_DIGESTINIT:
		case EVP_PKEY_CTRL_PKCS7_SIGN:
		case EVP_PKEY_CTRL_CMS_SIGN:
		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 = EC_curve_nist2nid(value);
		if (nid == NID_undef)
			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);
		}
	else if (!strcmp(type, "ec_param_enc"))
		{
		int param_enc;
		if (!strcmp(value, "explicit"))
			param_enc = 0;
		else if (!strcmp(value, "named_curve"))
			param_enc = OPENSSL_EC_NAMED_CURVE;
		else
			return -2;
		return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
		}
	else if (!strcmp(type, "ecdh_kdf_md"))
		{
		const EVP_MD *md;
		if (!(md = EVP_get_digestbyname(value)))
			{
			ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_DIGEST);
			return 0;
			}
		return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
		}
	else if (!strcmp(type, "ecdh_cofactor_mode"))
		{
		int co_mode;
		co_mode = atoi(value);
		return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
		}
			
	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;
	EC_PKEY_CTX *dctx = ctx->data;
	if (ctx->pkey == NULL && dctx->gen_group == 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);
	if (ctx->pkey)
		{
		/* Note: if error return, pkey is freed by parent routine */
		if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
			return 0;
		}
	else
		{
		if (!EC_KEY_set_group(ec, dctx->gen_group))
			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_copy,
	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_kdf_derive,

	pkey_ec_ctrl,
	pkey_ec_ctrl_str

	};