/*

 * Copyright 2020-2026 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include <stdlib.h>

#include <openssl/objects.h>

#include <openssl/evp.h>

#include "internal/cryptlib.h"

#include "internal/provider.h"

#include "internal/core.h"

#include "crypto/evp.h"

#include "evp_local.h"

static void evp_kem_free(void *data)

{

    EVP_KEM *kem = (EVP_KEM *)data;

    int i;

    if (kem == NULL)

        return;

    CRYPTO_DOWN_REF(&kem->refcnt, &i);

    if (i > 0)

        return;

    OPENSSL_free(kem->type_name);

    ossl_provider_free(kem->prov);

    CRYPTO_FREE_REF(&kem->refcnt);

    OPENSSL_free(kem);

}

static int evp_kem_up_ref(void *data)

{

    EVP_KEM *kem = (EVP_KEM *)data;

    int ref = 0;

    CRYPTO_UP_REF(&kem->refcnt, &ref);

    return 1;

}

static int evp_kem_init(EVP_PKEY_CTX *ctx, int operation,

    const OSSL_PARAM params[], EVP_PKEY *authkey)

{

    int ret = 0;

    EVP_KEM *kem = NULL;

    EVP_KEYMGMT *tmp_keymgmt = NULL;

    const OSSL_PROVIDER *tmp_prov = NULL;

    void *provkey = NULL, *provauthkey = NULL;

    const char *supported_kem = NULL;

    int iter;

    if (ctx == NULL || ctx->keytype == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

        return 0;

    }

    evp_pkey_ctx_free_old_ops(ctx);

    ctx->operation = operation;

    if (ctx->pkey == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_NO_KEY_SET);

        goto err;

    }

    if (authkey != NULL && authkey->type != ctx->pkey->type) {

        ERR_raise(ERR_LIB_EVP, EVP_R_DIFFERENT_KEY_TYPES);

        return 0;

    }

    /*

     * Try to derive the supported kem from |ctx->keymgmt|.

     */

    if (!ossl_assert(ctx->pkey->keymgmt == NULL

            || ctx->pkey->keymgmt == ctx->keymgmt)) {

        ERR_raise(ERR_LIB_EVP, ERR_R_INTERNAL_ERROR);

        goto err;

    }

    supported_kem = evp_keymgmt_util_query_operation_name(ctx->keymgmt,

        OSSL_OP_KEM);

    if (supported_kem == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

        goto err;

    }

    /*

     * Because we cleared out old ops, we shouldn't need to worry about

     * checking if kem is already there.

     * We perform two iterations:

     *

     * 1.  Do the normal kem fetch, using the fetching data given by

     *     the EVP_PKEY_CTX.

     * 2.  Do the provider specific kem fetch, from the same provider

     *     as |ctx->keymgmt|

     *

     * We then try to fetch the keymgmt from the same provider as the

     * kem, and try to export |ctx->pkey| to that keymgmt (when this

     * keymgmt happens to be the same as |ctx->keymgmt|, the export is

     * a no-op, but we call it anyway to not complicate the code even

     * more).

     * If the export call succeeds (returns a non-NULL provider key pointer),

     * we're done and can perform the operation itself.  If not, we perform

     * the second iteration, or jump to legacy.

     */

    for (iter = 1, provkey = NULL; iter < 3 && provkey == NULL; iter++) {

        EVP_KEYMGMT *tmp_keymgmt_tofree = NULL;

        /*

         * If we're on the second iteration, free the results from the first.

         * They are NULL on the first iteration, so no need to check what

         * iteration we're on.

         */

        EVP_KEM_free(kem);

        kem = NULL;

        EVP_KEYMGMT_free(tmp_keymgmt);

        tmp_keymgmt = NULL;

        switch (iter) {

        case 1:

            kem = EVP_KEM_fetch(ctx->libctx, supported_kem, ctx->propquery);

            if (kem != NULL)

                tmp_prov = EVP_KEM_get0_provider(kem);

            break;

        case 2:

            tmp_prov = EVP_KEYMGMT_get0_provider(ctx->keymgmt);

            kem = evp_kem_fetch_from_prov((OSSL_PROVIDER *)tmp_prov,

                supported_kem, ctx->propquery);

            if (kem == NULL) {

                ERR_raise(ERR_LIB_EVP,

                    EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

                ret = -2;

                goto err;

            }

        }

        if (kem == NULL)

            continue;

        /*

         * Ensure that the key is provided, either natively, or as a cached

         * export.  We start by fetching the keymgmt with the same name as

         * |ctx->pkey|, but from the provider of the kem method, using the

         * same property query as when fetching the kem method.

         * With the keymgmt we found (if we did), we try to export |ctx->pkey|

         * to it (evp_pkey_export_to_provider() is smart enough to only actually

         * export it if |tmp_keymgmt| is different from |ctx->pkey|'s keymgmt)

         */

        tmp_keymgmt_tofree = tmp_keymgmt = evp_keymgmt_fetch_from_prov((OSSL_PROVIDER *)tmp_prov,

            EVP_KEYMGMT_get0_name(ctx->keymgmt),

            ctx->propquery);

        if (tmp_keymgmt != NULL) {

            provkey = evp_pkey_export_to_provider(ctx->pkey, ctx->libctx,

                &tmp_keymgmt, ctx->propquery);

            if (provkey != NULL && authkey != NULL) {

                provauthkey = evp_pkey_export_to_provider(authkey, ctx->libctx,

                    &tmp_keymgmt,

                    ctx->propquery);

                if (provauthkey == NULL) {

                    EVP_KEM_free(kem);

                    ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

                    goto err;

                }

            }

        }

        if (tmp_keymgmt == NULL)

            EVP_KEYMGMT_free(tmp_keymgmt_tofree);

    }

    if (provkey == NULL) {

        EVP_KEM_free(kem);

        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

        goto err;

    }

    ctx->op.encap.kem = kem;

    ctx->op.encap.algctx = kem->newctx(ossl_provider_ctx(kem->prov));

    if (ctx->op.encap.algctx == NULL) {

        /* The provider key can stay in the cache */

        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

        goto err;

    }

    switch (operation) {

    case EVP_PKEY_OP_ENCAPSULATE:

        if (provauthkey != NULL && kem->auth_encapsulate_init != NULL) {

            ret = kem->auth_encapsulate_init(ctx->op.encap.algctx, provkey,

                provauthkey, params);

        } else if (provauthkey == NULL && kem->encapsulate_init != NULL) {

            ret = kem->encapsulate_init(ctx->op.encap.algctx, provkey, params);

        } else {

            ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

            ret = -2;

            goto err;

        }

        break;

    case EVP_PKEY_OP_DECAPSULATE:

        if (provauthkey != NULL && kem->auth_decapsulate_init != NULL) {

            ret = kem->auth_decapsulate_init(ctx->op.encap.algctx, provkey,

                provauthkey, params);

        } else if (provauthkey == NULL && kem->decapsulate_init != NULL) {

            ret = kem->decapsulate_init(ctx->op.encap.algctx, provkey, params);

        } else {

            ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

            ret = -2;

            goto err;

        }

        break;

    default:

        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);

        goto err;

    }

    EVP_KEYMGMT_free(tmp_keymgmt);

    tmp_keymgmt = NULL;

    if (ret > 0)

        return 1;

err:

    if (ret <= 0) {

        evp_pkey_ctx_free_old_ops(ctx);

        ctx->operation = EVP_PKEY_OP_UNDEFINED;

    }

    EVP_KEYMGMT_free(tmp_keymgmt);

    return ret;

}

int EVP_PKEY_auth_encapsulate_init(EVP_PKEY_CTX *ctx, EVP_PKEY *authpriv,

    const OSSL_PARAM params[])

{

    if (authpriv == NULL)

        return 0;

    return evp_kem_init(ctx, EVP_PKEY_OP_ENCAPSULATE, params, authpriv);

}

int EVP_PKEY_encapsulate_init(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[])

{

    return evp_kem_init(ctx, EVP_PKEY_OP_ENCAPSULATE, params, NULL);

}

int EVP_PKEY_encapsulate(EVP_PKEY_CTX *ctx,

    unsigned char *out, size_t *outlen,

    unsigned char *secret, size_t *secretlen)

{

    if (ctx == NULL)

        return 0;

    if (ctx->operation != EVP_PKEY_OP_ENCAPSULATE) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_INITIALIZED);

        return -1;

    }

    if (ctx->op.encap.algctx == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

        return -2;

    }

    if (out != NULL && secret == NULL)

        return 0;

    return ctx->op.encap.kem->encapsulate(ctx->op.encap.algctx,

        out, outlen, secret, secretlen);

}

int EVP_PKEY_decapsulate_init(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[])

{

    return evp_kem_init(ctx, EVP_PKEY_OP_DECAPSULATE, params, NULL);

}

int EVP_PKEY_auth_decapsulate_init(EVP_PKEY_CTX *ctx, EVP_PKEY *authpub,

    const OSSL_PARAM params[])

{

    if (authpub == NULL)

        return 0;

    return evp_kem_init(ctx, EVP_PKEY_OP_DECAPSULATE, params, authpub);

}

int EVP_PKEY_decapsulate(EVP_PKEY_CTX *ctx,

    unsigned char *secret, size_t *secretlen,

    const unsigned char *in, size_t inlen)

{

    if (ctx == NULL

        || (in == NULL || inlen == 0)

        || (secret == NULL && secretlen == NULL))

        return 0;

    if (ctx->operation != EVP_PKEY_OP_DECAPSULATE) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_INITIALIZED);

        return -1;

    }

    if (ctx->op.encap.algctx == NULL) {

        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);

        return -2;

    }

    return ctx->op.encap.kem->decapsulate(ctx->op.encap.algctx,

        secret, secretlen, in, inlen);

}

static EVP_KEM *evp_kem_new(OSSL_PROVIDER *prov)

{

    EVP_KEM *kem = OPENSSL_zalloc(sizeof(EVP_KEM));

    if (kem == NULL)

        return NULL;

    if (!CRYPTO_NEW_REF(&kem->refcnt, 1)

        || !ossl_provider_up_ref(prov)) {

        CRYPTO_FREE_REF(&kem->refcnt);

        OPENSSL_free(kem);

        return NULL;

    }

    kem->prov = prov;

    return kem;

}

static void *evp_kem_from_algorithm(int name_id, const OSSL_ALGORITHM *algodef,

    OSSL_PROVIDER *prov, int no_store)

{

    const OSSL_DISPATCH *fns = algodef->implementation;

    EVP_KEM *kem = NULL;

    int ctxfncnt = 0, encfncnt = 0, decfncnt = 0;

    int gparamfncnt = 0, sparamfncnt = 0;

    if ((kem = evp_kem_new(prov)) == NULL) {

        ERR_raise(ERR_LIB_EVP, ERR_R_EVP_LIB);

        goto err;

    }

    kem->name_id = name_id;

    kem->no_store = no_store;

    if ((kem->type_name = ossl_algorithm_get1_first_name(algodef)) == NULL)

        goto err;

    kem->description = algodef->algorithm_description;

    for (; fns->function_id != 0; fns++) {

        switch (fns->function_id) {

        case OSSL_FUNC_KEM_NEWCTX:

            if (kem->newctx != NULL)

                break;

            kem->newctx = OSSL_FUNC_kem_newctx(fns);

            ctxfncnt++;

            break;

        case OSSL_FUNC_KEM_ENCAPSULATE_INIT:

            if (kem->encapsulate_init != NULL)

                break;

            kem->encapsulate_init = OSSL_FUNC_kem_encapsulate_init(fns);

            encfncnt++;

            break;

        case OSSL_FUNC_KEM_AUTH_ENCAPSULATE_INIT:

            if (kem->auth_encapsulate_init != NULL)

                break;

            kem->auth_encapsulate_init = OSSL_FUNC_kem_auth_encapsulate_init(fns);

            encfncnt++;

            break;

        case OSSL_FUNC_KEM_ENCAPSULATE:

            if (kem->encapsulate != NULL)

                break;

            kem->encapsulate = OSSL_FUNC_kem_encapsulate(fns);

            encfncnt++;

            break;

        case OSSL_FUNC_KEM_DECAPSULATE_INIT:

            if (kem->decapsulate_init != NULL)

                break;

            kem->decapsulate_init = OSSL_FUNC_kem_decapsulate_init(fns);

            decfncnt++;

            break;

        case OSSL_FUNC_KEM_AUTH_DECAPSULATE_INIT:

            if (kem->auth_decapsulate_init != NULL)

                break;

            kem->auth_decapsulate_init = OSSL_FUNC_kem_auth_decapsulate_init(fns);

            decfncnt++;

            break;

        case OSSL_FUNC_KEM_DECAPSULATE:

            if (kem->decapsulate != NULL)

                break;

            kem->decapsulate = OSSL_FUNC_kem_decapsulate(fns);

            decfncnt++;

            break;

        case OSSL_FUNC_KEM_FREECTX:

            if (kem->freectx != NULL)

                break;

            kem->freectx = OSSL_FUNC_kem_freectx(fns);

            ctxfncnt++;

            break;

        case OSSL_FUNC_KEM_DUPCTX:

            if (kem->dupctx != NULL)

                break;

            kem->dupctx = OSSL_FUNC_kem_dupctx(fns);

            break;

        case OSSL_FUNC_KEM_GET_CTX_PARAMS:

            if (kem->get_ctx_params != NULL)

                break;

            kem->get_ctx_params

                = OSSL_FUNC_kem_get_ctx_params(fns);

            gparamfncnt++;

            break;

        case OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS:

            if (kem->gettable_ctx_params != NULL)

                break;

            kem->gettable_ctx_params

                = OSSL_FUNC_kem_gettable_ctx_params(fns);

            gparamfncnt++;

            break;

        case OSSL_FUNC_KEM_SET_CTX_PARAMS:

            if (kem->set_ctx_params != NULL)

                break;

            kem->set_ctx_params

                = OSSL_FUNC_kem_set_ctx_params(fns);

            sparamfncnt++;

            break;

        case OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS:

            if (kem->settable_ctx_params != NULL)

                break;

            kem->settable_ctx_params

                = OSSL_FUNC_kem_settable_ctx_params(fns);

            sparamfncnt++;

            break;

        }

    }

    if (ctxfncnt != 2

        || (encfncnt != 0 && encfncnt != 2 && encfncnt != 3)

        || (decfncnt != 0 && decfncnt != 2 && decfncnt != 3)

        || (encfncnt != decfncnt)

        || (gparamfncnt != 0 && gparamfncnt != 2)

        || (sparamfncnt != 0 && sparamfncnt != 2)) {

        /*

         * In order to be a consistent set of functions we must have at least

         * a set of context functions (newctx and freectx) as well as a pair

         * (or triplet) of "kem" functions:

         * (encapsulate_init, (and/or auth_encapsulate_init), encapsulate) or

         * (decapsulate_init, (and/or auth_decapsulate_init), decapsulate).

         * set_ctx_params and settable_ctx_params are optional, but if one of

         * them is present then the other one must also be present. The same

         * applies to get_ctx_params and gettable_ctx_params.

         * The dupctx function is optional.

         */

        ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_PROVIDER_FUNCTIONS);

        goto err;

    }

    return kem;

err:

    evp_kem_free(kem);

    return NULL;

}

void EVP_KEM_free(EVP_KEM *kem)

{

#ifdef OPENSSL_NO_CACHED_FETCH

    evp_kem_free(kem);

#else

    if (kem != NULL && (kem->no_store != 0))

        evp_kem_free(kem);

#endif

}

int EVP_KEM_up_ref(EVP_KEM *kem)

{

#ifdef OPENSSL_NO_CACHED_FETCH

    return evp_kem_up_ref(kem);

#else

    if (kem->no_store != 0)

        return evp_kem_up_ref(kem);

    return 1;

#endif

}

OSSL_PROVIDER *EVP_KEM_get0_provider(const EVP_KEM *kem)

{

    return kem->prov;

}

EVP_KEM *EVP_KEM_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,

    const char *properties)

{

    return evp_generic_fetch(ctx, OSSL_OP_KEM, algorithm, properties,

        evp_kem_from_algorithm,

        evp_kem_up_ref,

        evp_kem_free);

}

EVP_KEM *evp_kem_fetch_from_prov(OSSL_PROVIDER *prov, const char *algorithm,

    const char *properties)

{

    return evp_generic_fetch_from_prov(prov, OSSL_OP_KEM, algorithm, properties,

        evp_kem_from_algorithm,

        evp_kem_up_ref,

        evp_kem_free);

}

int EVP_KEM_is_a(const EVP_KEM *kem, const char *name)

{

    return kem != NULL && evp_is_a(kem->prov, kem->name_id, NULL, name);

}

int evp_kem_get_number(const EVP_KEM *kem)

{

    return kem->name_id;

}

const char *EVP_KEM_get0_name(const EVP_KEM *kem)

{

    return kem->type_name;

}

const char *EVP_KEM_get0_description(const EVP_KEM *kem)

{

    return kem->description;

}

void EVP_KEM_do_all_provided(OSSL_LIB_CTX *libctx,

    void (*fn)(EVP_KEM *kem, void *arg),

    void *arg)

{

    struct EVP_KEM_do_all_provided_thunk t;

    t.fn = fn;

    t.arg = arg;

    evp_generic_do_all(libctx, OSSL_OP_KEM, EVP_KEM_do_all_provided_thunk, &t,

        evp_kem_from_algorithm,

        evp_kem_up_ref,

        evp_kem_free);

}

int EVP_KEM_names_do_all(const EVP_KEM *kem,

    void (*fn)(const char *name, void *data),

    void *data)

{

    if (kem->prov != NULL)

        return evp_names_do_all(kem->prov, kem->name_id, fn, data);

    return 1;

}

const OSSL_PARAM *EVP_KEM_gettable_ctx_params(const EVP_KEM *kem)

{

    void *provctx;

    if (kem == NULL || kem->gettable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_KEM_get0_provider(kem));

    return kem->gettable_ctx_params(NULL, provctx);

}

const OSSL_PARAM *EVP_KEM_settable_ctx_params(const EVP_KEM *kem)

{

    void *provctx;

    if (kem == NULL || kem->settable_ctx_params == NULL)

        return NULL;

    provctx = ossl_provider_ctx(EVP_KEM_get0_provider(kem));

    return kem->settable_ctx_params(NULL, provctx);

}