/* $OpenBSD: dh_ameth.c,v 1.24 2022/06/27 12:36:05 tb 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_locl.h"
#include "dh_local.h"
#include "evp_locl.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 paramaters, 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,
};