/* $OpenBSD: dh_ameth.c,v 1.26 2022/12/26 07:18:51 jmc Exp $ */
/* 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 <openssl/asn1.h>
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/x509.h>

#include "asn1_local.h"
#include "dh_local.h"
#include "evp_local.h"

static void
int_dh_free(EVP_PKEY *pkey)
{
	DH_free(pkey->pkey.dh);
}

static int
dh_pub_decode(EVP_PKEY *pkey, X509_PUBKEY *pubkey)
{
	const unsigned char *p, *pm;
	int pklen, pmlen;
	int ptype;
	const void *pval;
	const ASN1_STRING *pstr;
	X509_ALGOR *palg;
	ASN1_INTEGER *public_key = NULL;
	DH *dh = NULL;

	if (!X509_PUBKEY_get0_param(NULL, &p, &pklen, &palg, pubkey))
		return 0;
	X509_ALGOR_get0(NULL, &ptype, &pval, palg);

	if (ptype != V_ASN1_SEQUENCE) {
		DHerror(DH_R_PARAMETER_ENCODING_ERROR);
		goto err;
	}

	pstr = pval;
	pm = pstr->data;
	pmlen = pstr->length;

	if (!(dh = d2i_DHparams(NULL, &pm, pmlen))) {
		DHerror(DH_R_DECODE_ERROR);
		goto err;
	}

	if (!(public_key=d2i_ASN1_INTEGER(NULL, &p, pklen))) {
		DHerror(DH_R_DECODE_ERROR);
		goto err;
	}

	/* We have parameters now set public key */
	if (!(dh->pub_key = ASN1_INTEGER_to_BN(public_key, NULL))) {
		DHerror(DH_R_BN_DECODE_ERROR);
		goto err;
	}

	ASN1_INTEGER_free(public_key);
	EVP_PKEY_assign_DH(pkey, dh);
	return 1;

err:
	if (public_key)
		ASN1_INTEGER_free(public_key);
	DH_free(dh);
	return 0;
}

static int
dh_pub_encode(X509_PUBKEY *pk, const EVP_PKEY *pkey)
{
	DH *dh;
	int ptype;
	unsigned char *penc = NULL;
	int penclen;
	ASN1_STRING *str;
	ASN1_INTEGER *pub_key = NULL;

	dh=pkey->pkey.dh;

	str = ASN1_STRING_new();
	if (str == NULL) {
		DHerror(ERR_R_MALLOC_FAILURE);
		goto err;
	}

	str->length = i2d_DHparams(dh, &str->data);
	if (str->length <= 0) {
		DHerror(ERR_R_MALLOC_FAILURE);
		goto err;
	}
	ptype = V_ASN1_SEQUENCE;

	pub_key = BN_to_ASN1_INTEGER(dh->pub_key, NULL);
	if (!pub_key)
		goto err;

	penclen = i2d_ASN1_INTEGER(pub_key, &penc);

	ASN1_INTEGER_free(pub_key);

	if (penclen <= 0) {
		DHerror(ERR_R_MALLOC_FAILURE);
		goto err;
		}

	if (X509_PUBKEY_set0_param(pk, OBJ_nid2obj(EVP_PKEY_DH), ptype,
	    (void *)str, penc, penclen))
		return 1;

err:
	free(penc);
	ASN1_STRING_free(str);

	return 0;
}

/*
 * PKCS#8 DH is defined in PKCS#11 of all places. It is similar to DH in
 * that the AlgorithmIdentifier contains the parameters, the private key
 * is explcitly included and the pubkey must be recalculated.
 */

static int
dh_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
{
	const unsigned char *p, *pm;
	int pklen, pmlen;
	int ptype;
	const void *pval;
	const ASN1_STRING *pstr;
	const X509_ALGOR *palg;
	ASN1_INTEGER *privkey = NULL;
	DH *dh = NULL;

	if (!PKCS8_pkey_get0(NULL, &p, &pklen, &palg, p8))
		return 0;

	X509_ALGOR_get0(NULL, &ptype, &pval, palg);

	if (ptype != V_ASN1_SEQUENCE)
		goto decerr;

	if (!(privkey=d2i_ASN1_INTEGER(NULL, &p, pklen)))
		goto decerr;

	pstr = pval;
	pm = pstr->data;
	pmlen = pstr->length;
	if (!(dh = d2i_DHparams(NULL, &pm, pmlen)))
		goto decerr;
	/* We have parameters now set private key */
	if (!(dh->priv_key = ASN1_INTEGER_to_BN(privkey, NULL))) {
		DHerror(DH_R_BN_ERROR);
		goto dherr;
	}
	/* Calculate public key */
	if (!DH_generate_key(dh))
		goto dherr;

	EVP_PKEY_assign_DH(pkey, dh);

	ASN1_INTEGER_free(privkey);

	return 1;

decerr:
	DHerror(EVP_R_DECODE_ERROR);
dherr:
	ASN1_INTEGER_free(privkey);
	DH_free(dh);
	return 0;
}

static int
dh_priv_encode(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pkey)
{
	ASN1_STRING *params = NULL;
	ASN1_INTEGER *prkey = NULL;
	unsigned char *dp = NULL;
	int dplen;

	params = ASN1_STRING_new();

	if (!params) {
		DHerror(ERR_R_MALLOC_FAILURE);
		goto err;
	}

	params->length = i2d_DHparams(pkey->pkey.dh, &params->data);
	if (params->length <= 0) {
		DHerror(ERR_R_MALLOC_FAILURE);
		goto err;
	}
	params->type = V_ASN1_SEQUENCE;

	/* Get private key into integer */
	prkey = BN_to_ASN1_INTEGER(pkey->pkey.dh->priv_key, NULL);

	if (!prkey) {
		DHerror(DH_R_BN_ERROR);
		goto err;
	}

	dplen = i2d_ASN1_INTEGER(prkey, &dp);

	ASN1_INTEGER_free(prkey);
	prkey = NULL;

	if (!PKCS8_pkey_set0(p8, OBJ_nid2obj(NID_dhKeyAgreement), 0,
	    V_ASN1_SEQUENCE, params, dp, dplen))
		goto err;

	return 1;

err:
	free(dp);
	ASN1_STRING_free(params);
	ASN1_INTEGER_free(prkey);
	return 0;
}

static void
update_buflen(const BIGNUM *b, size_t *pbuflen)
{
	size_t i;

	if (!b)
		return;
	if (*pbuflen < (i = (size_t)BN_num_bytes(b)))
		*pbuflen = i;
}

static int
dh_param_decode(EVP_PKEY *pkey, const unsigned char **pder, int derlen)
{
	DH *dh;

	if (!(dh = d2i_DHparams(NULL, pder, derlen))) {
		DHerror(ERR_R_DH_LIB);
		return 0;
	}
	EVP_PKEY_assign_DH(pkey, dh);
	return 1;
}

static int
dh_param_encode(const EVP_PKEY *pkey, unsigned char **pder)
{
	return i2d_DHparams(pkey->pkey.dh, pder);
}

static int
do_dh_print(BIO *bp, const DH *x, int indent, ASN1_PCTX *ctx, int ptype)
{
	unsigned char *m = NULL;
	int reason = ERR_R_BUF_LIB, ret = 0;
	size_t buf_len = 0;
	const char *ktype = NULL;
	BIGNUM *priv_key, *pub_key;

	if (ptype == 2)
		priv_key = x->priv_key;
	else
		priv_key = NULL;

	if (ptype > 0)
		pub_key = x->pub_key;
	else
		pub_key = NULL;

	update_buflen(x->p, &buf_len);

	if (buf_len == 0) {
		reason = ERR_R_PASSED_NULL_PARAMETER;
		goto err;
	}

	update_buflen(x->g, &buf_len);
	update_buflen(pub_key, &buf_len);
	update_buflen(priv_key, &buf_len);

	if (ptype == 2)
		ktype = "PKCS#3 DH Private-Key";
	else if (ptype == 1)
		ktype = "PKCS#3 DH Public-Key";
	else
		ktype = "PKCS#3 DH Parameters";

	m= malloc(buf_len + 10);
	if (m == NULL) {
		reason = ERR_R_MALLOC_FAILURE;
		goto err;
	}

	if (!BIO_indent(bp, indent, 128))
		goto err;
	if (BIO_printf(bp, "%s: (%d bit)\n", ktype, BN_num_bits(x->p)) <= 0)
		goto err;
	indent += 4;

	if (!ASN1_bn_print(bp, "private-key:", priv_key, m, indent))
		goto err;
	if (!ASN1_bn_print(bp, "public-key:", pub_key, m, indent))
		goto err;

	if (!ASN1_bn_print(bp, "prime:", x->p, m, indent))
		goto err;
	if (!ASN1_bn_print(bp, "generator:", x->g, m, indent))
		goto err;
	if (x->length != 0) {
		if (!BIO_indent(bp, indent, 128))
			goto err;
		if (BIO_printf(bp, "recommended-private-length: %d bits\n",
		    (int)x->length) <= 0)
			goto err;
	}

	ret = 1;
	if (0) {
err:
		DHerror(reason);
	}
	free(m);
	return(ret);
}

static int
int_dh_size(const EVP_PKEY *pkey)
{
	return DH_size(pkey->pkey.dh);
}

static int
dh_bits(const EVP_PKEY *pkey)
{
	return BN_num_bits(pkey->pkey.dh->p);
}

static int
dh_security_bits(const EVP_PKEY *pkey)
{
	return DH_security_bits(pkey->pkey.dh);
}

static int
dh_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b)
{
	if (BN_cmp(a->pkey.dh->p, b->pkey.dh->p) ||
	    BN_cmp(a->pkey.dh->g, b->pkey.dh->g))
		return 0;
	else
		return 1;
}

static int
dh_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from)
{
	BIGNUM *a;

	if ((a = BN_dup(from->pkey.dh->p)) == NULL)
		return 0;
	BN_free(to->pkey.dh->p);
	to->pkey.dh->p = a;

	if ((a = BN_dup(from->pkey.dh->g)) == NULL)
		return 0;
	BN_free(to->pkey.dh->g);
	to->pkey.dh->g = a;

	return 1;
}

static int
dh_missing_parameters(const EVP_PKEY *a)
{
	if (!a->pkey.dh->p || !a->pkey.dh->g)
		return 1;
	return 0;
}

static int
dh_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
{
	if (dh_cmp_parameters(a, b) == 0)
		return 0;
	if (BN_cmp(b->pkey.dh->pub_key, a->pkey.dh->pub_key) != 0)
		return 0;
	else
		return 1;
}

static int
dh_param_print(BIO *bp, const EVP_PKEY *pkey, int indent, ASN1_PCTX *ctx)
{
	return do_dh_print(bp, pkey->pkey.dh, indent, ctx, 0);
}

static int
dh_public_print(BIO *bp, const EVP_PKEY *pkey, int indent, ASN1_PCTX *ctx)
{
	return do_dh_print(bp, pkey->pkey.dh, indent, ctx, 1);
}

static int
dh_private_print(BIO *bp, const EVP_PKEY *pkey, int indent, ASN1_PCTX *ctx)
{
	return do_dh_print(bp, pkey->pkey.dh, indent, ctx, 2);
}

int
DHparams_print(BIO *bp, const DH *x)
{
	return do_dh_print(bp, x, 4, NULL, 0);
}

static int
dh_pkey_public_check(const EVP_PKEY *pkey)
{
	DH *dh = pkey->pkey.dh;

	if (dh->pub_key == NULL) {
		DHerror(DH_R_MISSING_PUBKEY);
		return 0;
	}

	return DH_check_pub_key_ex(dh, dh->pub_key);
}

static int
dh_pkey_param_check(const EVP_PKEY *pkey)
{
	DH *dh = pkey->pkey.dh;

	/*
	 * It would have made more sense to support EVP_PKEY_check() for DH
	 * keys and call DH_check_ex() there and keeping this as a wrapper
	 * for DH_param_check_ex(). We follow OpenSSL's choice.
	 */
	return DH_check_ex(dh);
}

const EVP_PKEY_ASN1_METHOD dh_asn1_meth = {
	.pkey_id = EVP_PKEY_DH,
	.pkey_base_id = EVP_PKEY_DH,

	.pem_str = "DH",
	.info = "OpenSSL PKCS#3 DH method",

	.pub_decode = dh_pub_decode,
	.pub_encode = dh_pub_encode,
	.pub_cmp = dh_pub_cmp,
	.pub_print = dh_public_print,

	.priv_decode = dh_priv_decode,
	.priv_encode = dh_priv_encode,
	.priv_print = dh_private_print,

	.pkey_size = int_dh_size,
	.pkey_bits = dh_bits,
	.pkey_security_bits = dh_security_bits,

	.param_decode = dh_param_decode,
	.param_encode = dh_param_encode,
	.param_missing = dh_missing_parameters,
	.param_copy = dh_copy_parameters,
	.param_cmp = dh_cmp_parameters,
	.param_print = dh_param_print,

	.pkey_free = int_dh_free,

	.pkey_check = NULL,
	.pkey_public_check = dh_pkey_public_check,
	.pkey_param_check = dh_pkey_param_check,
};