/* $OpenBSD: dh_pmeth.c,v 1.18 2025/05/10 05:54:38 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 <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/asn1t.h>
#include <openssl/bn.h>
#include <openssl/dh.h>
#include <openssl/evp.h>
#include <openssl/x509.h>

#include "bn_local.h"
#include "dh_local.h"
#include "err_local.h"
#include "evp_local.h"

/* DH pkey context structure */

typedef struct {
        /* Parameter gen parameters */
        int prime_len;
        int generator;
        int use_dsa;
        /* Keygen callback info */
        int gentmp[2];
        /* message digest */
} DH_PKEY_CTX;

static int
pkey_dh_init(EVP_PKEY_CTX *ctx)
{
        DH_PKEY_CTX *dctx;

        dctx = malloc(sizeof(DH_PKEY_CTX));
        if (!dctx)
                return 0;
        dctx->prime_len = 1024;
        dctx->generator = 2;
        dctx->use_dsa = 0;

        ctx->data = dctx;
        ctx->keygen_info = dctx->gentmp;
        ctx->keygen_info_count = 2;

        return 1;
}

static int
pkey_dh_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
{
        DH_PKEY_CTX *dctx, *sctx;

        if (!pkey_dh_init(dst))
                return 0;
        sctx = src->data;
        dctx = dst->data;
        dctx->prime_len = sctx->prime_len;
        dctx->generator = sctx->generator;
        dctx->use_dsa = sctx->use_dsa;
        return 1;
}

static void
pkey_dh_cleanup(EVP_PKEY_CTX *ctx)
{
        DH_PKEY_CTX *dctx = ctx->data;

        free(dctx);
}

static int
pkey_dh_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
{
        DH_PKEY_CTX *dctx = ctx->data;

        switch (type) {
        case EVP_PKEY_CTRL_DH_PARAMGEN_PRIME_LEN:
                if (p1 < 256)
                        return -2;
                dctx->prime_len = p1;
                return 1;

        case EVP_PKEY_CTRL_DH_PARAMGEN_GENERATOR:
                dctx->generator = p1;
                return 1;

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

        default:
                return -2;
        }
}

static int
pkey_dh_ctrl_str(EVP_PKEY_CTX *ctx, const char *type, const char *value)
{
        const char *errstr;
        int len;

        if (!strcmp(type, "dh_paramgen_prime_len")) {
                len = strtonum(value, INT_MIN, INT_MAX, &errstr);
                if (errstr != NULL)
                        return -2;
                return EVP_PKEY_CTX_set_dh_paramgen_prime_len(ctx, len);
        } else if (!strcmp(type, "dh_paramgen_generator")) {
                len = strtonum(value, INT_MIN, INT_MAX, &errstr);
                if (errstr != NULL)
                        return -2;
                return EVP_PKEY_CTX_set_dh_paramgen_generator(ctx, len);
        }

        return -2;
}

static int
pkey_dh_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
        DH *dh;
        DH_PKEY_CTX *dctx = ctx->data;
        BN_GENCB *pcb = NULL;
        BN_GENCB cb = {0};
        int ret = 0;

        if ((dh = DH_new()) == NULL)
                goto err;
        if (ctx->pkey_gencb != NULL) {
                pcb = &cb;
                evp_pkey_set_cb_translate(pcb, ctx);
        }
        if (!DH_generate_parameters_ex(dh, dctx->prime_len, dctx->generator, pcb))
                goto err;
        if (!EVP_PKEY_assign_DH(pkey, dh))
                goto err;
        dh = NULL;

        ret = 1;
 err:
        DH_free(dh);

        return ret;
}

static int
pkey_dh_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
        DH *dh = NULL;
        int ret = 0;

        if (ctx->pkey == NULL) {
                DHerror(DH_R_NO_PARAMETERS_SET);
                goto err;
        }

        if ((dh = DH_new()) == NULL)
                goto err;
        if (!EVP_PKEY_set1_DH(pkey, dh))
                goto err;

        if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
                goto err;
        if (!DH_generate_key(dh))
                goto err;

        ret = 1;

 err:
        DH_free(dh);

        return ret;
}

static int
pkey_dh_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
{
        int ret;

        if (!ctx->pkey || !ctx->peerkey) {
                DHerror(DH_R_KEYS_NOT_SET);
                return 0;
        }
        ret = DH_compute_key(key, ctx->peerkey->pkey.dh->pub_key,
            ctx->pkey->pkey.dh);
        if (ret < 0)
                return ret;
        *keylen = ret;
        return 1;
}

const EVP_PKEY_METHOD dh_pkey_meth = {
        .pkey_id = EVP_PKEY_DH,
        .flags = EVP_PKEY_FLAG_AUTOARGLEN,

        .init = pkey_dh_init,
        .copy = pkey_dh_copy,
        .cleanup = pkey_dh_cleanup,

        .paramgen = pkey_dh_paramgen,

        .keygen = pkey_dh_keygen,

        .derive = pkey_dh_derive,

        .ctrl = pkey_dh_ctrl,
        .ctrl_str = pkey_dh_ctrl_str
};