/* $OpenBSD: ec_pmeth.c,v 1.27 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 <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/asn1t.h>
#include <openssl/ec.h>
#include <openssl/evp.h>
#include <openssl/x509.h>

#include "bn_local.h"
#include "ec_local.h"
#include "err_local.h"
#include "evp_local.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;

        if ((dctx = calloc(1, sizeof(EC_PKEY_CTX))) == NULL) {
                ECerror(ERR_R_MALLOC_FAILURE);
                return 0;
        }

        dctx->cofactor_mode = -1;
        dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;

        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) {
                if ((dctx->kdf_ukm = calloc(1, sctx->kdf_ukmlen)) == NULL)
                        return 0;
                memcpy(dctx->kdf_ukm, sctx->kdf_ukm, sctx->kdf_ukmlen);
        } 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 != NULL) {
                EC_GROUP_free(dctx->gen_group);
                EC_KEY_free(dctx->co_key);
                free(dctx->kdf_ukm);
                free(dctx);
                ctx->data = NULL;
        }
}

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)) {
                ECerror(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) {
                ECerror(EC_R_KEYS_NOT_SET);
                return 0;
        }

        eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
        if (key == NULL) {
                *keylen = BN_num_bytes(eckey->group->p);
                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, NULL);
        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;
        if ((ktmp = calloc(1, ktmplen)) == NULL) {
                ECerror(ERR_R_MALLOC_FAILURE);
                return 0;
        }
        if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
                goto err;
        /* Do KDF stuff */
        if (!ecdh_KDF_X9_63(key, *keylen, ktmp, ktmplen, dctx->kdf_ukm,
            dctx->kdf_ukmlen, dctx->kdf_md))
                goto err;
        rv = 1;

 err:
        freezero(ktmp, ktmplen);

        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) {
                        ECerror(EC_R_INVALID_CURVE);
                        return 0;
                }
                EC_GROUP_free(dctx->gen_group);
                dctx->gen_group = group;
                return 1;

        case EVP_PKEY_CTRL_EC_PARAM_ENC:
                if (!dctx->gen_group) {
                        ECerror(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 {
                        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_63)
                        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:
                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:
                /* RFC 3279, RFC 5758 and NIST CSOR. */
                switch (EVP_MD_type(p2)) {
                case NID_sha1:
                case NID_ecdsa_with_SHA1:
                case NID_sha224:
                case NID_sha256:
                case NID_sha384:
                case NID_sha512:
                case NID_sha3_224:
                case NID_sha3_256:
                case NID_sha3_384:
                case NID_sha3_512:
                        break;
                default:
                        ECerror(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) {
                        ECerror(EC_R_INVALID_CURVE);
                        return 0;
                }
                return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
        } else if (strcmp(type, "ec_param_enc") == 0) {
                int param_enc;
                if (strcmp(value, "explicit") == 0)
                        param_enc = 0;
                else if (strcmp(value, "named_curve") == 0)
                        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") == 0) {
                const EVP_MD *md;
                if ((md = EVP_get_digestbyname(value)) == NULL) {
                        ECerror(EC_R_INVALID_DIGEST);
                        return 0;
                }
                return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
        } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
                int cofactor_mode;
                const char *errstr;

                cofactor_mode = strtonum(value, -1, 1, &errstr);
                if (errstr != NULL)
                        return -2;
                return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, cofactor_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) {
                ECerror(EC_R_NO_PARAMETERS_SET);
                goto err;
        }

        if ((ec = EC_KEY_new()) == NULL)
                goto err;
        if (!EC_KEY_set_group(ec, dctx->gen_group))
                goto err;
        if (!EVP_PKEY_assign_EC_KEY(pkey, ec))
                goto err;
        ec = NULL;

        ret = 1;

 err:
        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;
        int ret = 0;

        if (ctx->pkey == NULL && dctx->gen_group == NULL) {
                ECerror(EC_R_NO_PARAMETERS_SET);
                goto err;
        }

        if ((ec = EC_KEY_new()) == NULL)
                goto err;
        if (!EVP_PKEY_set1_EC_KEY(pkey, ec))
                goto err;

        if (ctx->pkey != NULL) {
                if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
                        goto err;
        } else {
                if (!EC_KEY_set_group(ec, dctx->gen_group))
                        goto err;
        }

        if (!EC_KEY_generate_key(ec))
                goto err;

        ret = 1;

 err:
        EC_KEY_free(ec);

        return ret;
}

const EVP_PKEY_METHOD ec_pkey_meth = {
        .pkey_id = EVP_PKEY_EC,

        .init = pkey_ec_init,
        .copy = pkey_ec_copy,
        .cleanup = pkey_ec_cleanup,

        .paramgen = pkey_ec_paramgen,

        .keygen = pkey_ec_keygen,

        .sign = pkey_ec_sign,

        .verify = pkey_ec_verify,

        .derive = pkey_ec_kdf_derive,

        .ctrl = pkey_ec_ctrl,
        .ctrl_str = pkey_ec_ctrl_str
};