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EVP_KEM_free(3)                     OpenSSL                    EVP_KEM_free(3)



NAME
       EVP_KEM_fetch, EVP_KEM_free, EVP_KEM_up_ref, EVP_KEM_get0_name,
       EVP_KEM_is_a, EVP_KEM_get0_provider, EVP_KEM_do_all_provided,
       EVP_KEM_names_do_all, EVP_KEM_get0_description,
       EVP_KEM_gettable_ctx_params, EVP_KEM_settable_ctx_params - Functions to
       manage EVP_KEM algorithm objects

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/evp.h>

        EVP_KEM *EVP_KEM_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
                               const char *properties);
        void EVP_KEM_free(EVP_KEM *kem);
        int EVP_KEM_up_ref(EVP_KEM *kem);
        const char *EVP_KEM_get0_name(const EVP_KEM *kem);
        int EVP_KEM_is_a(const EVP_KEM *kem, const char *name);
        OSSL_PROVIDER *EVP_KEM_get0_provider(const EVP_KEM *kem);
        void EVP_KEM_do_all_provided(OSSL_LIB_CTX *libctx,
                                     void (*fn)(EVP_KEM *kem, void *arg), void *arg);
        int EVP_KEM_names_do_all(const EVP_KEM *kem,
                                 void (*fn)(const char *name, void *data), void *data);
        const char *EVP_KEM_get0_description(const EVP_KEM *kem);
        const OSSL_PARAM *EVP_KEM_gettable_ctx_params(const EVP_KEM *kem);
        const OSSL_PARAM *EVP_KEM_settable_ctx_params(const EVP_KEM *kem);

DESCRIPTION
       EVP_KEM_fetch() fetches the implementation for the given algorithm from
       any provider offering it, within the criteria given by the properties
       and in the scope of the given library context ctx (see
       OSSL_LIB_CTX(3)). The algorithm will be one offering functions for
       performing asymmetric kem related tasks such as key encapsulation and
       decapsulation.  See "ALGORITHM FETCHING" in crypto(7) for further
       information.

       The returned value must eventually be freed with EVP_KEM_free().

       EVP_KEM_free() decrements the reference count for the EVP_KEM
       structure.  Typically this structure will have been obtained from an
       earlier call to EVP_KEM_fetch(). If the reference count drops to 0 then
       the structure is freed.

       EVP_KEM_up_ref() increments the reference count for an EVP_KEM
       structure.

       EVP_KEM_is_a() returns 1 if kem is an implementation of an algorithm
       that's identifiable with name, otherwise 0.

       EVP_KEM_get0_provider() returns the provider that kem was fetched from.

       EVP_KEM_do_all_provided() traverses all EVP_KEMs implemented by all
       activated providers in the given library context libctx, and for each
       of the implementations, calls the given function fn with the
       implementation method and the given arg as argument.

       EVP_KEM_get0_name() returns the algorithm name from the provided
       implementation for the given kem. Note that the kem may have multiple
       synonyms associated with it. In this case the first name from the
       algorithm definition is returned. Ownership of the returned string is
       retained by the kem object and should not be freed by the caller.

       EVP_KEM_names_do_all() traverses all names for kem, and calls fn with
       each name and data.

       EVP_KEM_get0_description() returns a description of the kem, meant for
       display and human consumption.  The description is at the discretion of
       the kem implementation.

       EVP_KEM_gettable_ctx_params() and EVP_KEM_settable_ctx_params() return
       a constant OSSL_PARAM(3) array that describes the names and types of
       key parameters that can be retrieved or set by a key encapsulation
       algorithm using EVP_PKEY_CTX_get_params(3) and
       EVP_PKEY_CTX_set_params(3).

RETURN VALUES
       EVP_KEM_fetch() returns a pointer to an EVP_KEM for success or NULL for
       failure.

       EVP_KEM_up_ref() returns 1 for success or 0 otherwise.

       EVP_KEM_names_do_all() returns 1 if the callback was called for all
       names. A return value of 0 means that the callback was not called for
       any names.

       EVP_KEM_gettable_ctx_params() and EVP_KEM_settable_ctx_params() return
       a constant OSSL_PARAM(3) array or NULL on error.

SEE ALSO
       "ALGORITHM FETCHING" in crypto(7), OSSL_PROVIDER(3)

HISTORY
       The functions described here were added in OpenSSL 3.0.

COPYRIGHT
       Copyright 2020-2021 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>.



3.0.12                            2023-05-07                   EVP_KEM_free(3)