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EVP_KEYEXCH_free(3)                 OpenSSL                EVP_KEYEXCH_free(3)



NAME
       EVP_KEYEXCH_fetch, EVP_KEYEXCH_free, EVP_KEYEXCH_up_ref,
       EVP_KEYEXCH_get0_provider, EVP_KEYEXCH_is_a,
       EVP_KEYEXCH_do_all_provided, EVP_KEYEXCH_names_do_all,
       EVP_KEYEXCH_get0_name, EVP_KEYEXCH_get0_description,
       EVP_KEYEXCH_gettable_ctx_params, EVP_KEYEXCH_settable_ctx_params -
       Functions to manage EVP_KEYEXCH algorithm objects

LIBRARY
       libcrypto, -lcrypto

SYNOPSIS
        #include <openssl/evp.h>

        EVP_KEYEXCH *EVP_KEYEXCH_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
                                       const char *properties);
        void EVP_KEYEXCH_free(EVP_KEYEXCH *exchange);
        int EVP_KEYEXCH_up_ref(EVP_KEYEXCH *exchange);
        OSSL_PROVIDER *EVP_KEYEXCH_get0_provider(const EVP_KEYEXCH *exchange);
        int EVP_KEYEXCH_is_a(const EVP_KEYEXCH *exchange, const char *name);
        const char *EVP_KEYEXCH_get0_name(const EVP_KEYEXCH *exchange);
        void EVP_KEYEXCH_do_all_provided(OSSL_LIB_CTX *libctx,
                                         void (*fn)(EVP_KEYEXCH *exchange, void *arg),
                                         void *arg);
        int EVP_KEYEXCH_names_do_all(const EVP_KEYEXCH *exchange,
                                     void (*fn)(const char *name, void *data),
                                     void *data);
        const char *EVP_KEYEXCH_get0_description(const EVP_KEYEXCH *keyexch);
        const OSSL_PARAM *EVP_KEYEXCH_gettable_ctx_params(const EVP_KEYEXCH *keyexch);
        const OSSL_PARAM *EVP_KEYEXCH_settable_ctx_params(const EVP_KEYEXCH *keyexch);

DESCRIPTION
       EVP_KEYEXCH_fetch() fetches the key exchange implementation for the
       given algorithm from any provider offering it, within the criteria
       given by the properties.  See "ALGORITHM FETCHING" in crypto(7) for
       further information.

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

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

       EVP_KEYEXCH_up_ref() increments the reference count for an EVP_KEYEXCH
       structure.

       EVP_KEYEXCH_get0_provider() returns the provider that exchange was
       fetched from.

       EVP_KEYEXCH_is_a() checks if exchange is an implementation of an
       algorithm that's identifiable with name.

       EVP_KEYEXCH_get0_name() returns the algorithm name from the provided
       implementation for the given exchange. Note that the exchange 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 exchange object and should not be freed by the
       caller.

       EVP_KEYEXCH_names_do_all() traverses all names for the exchange, and
       calls fn with each name and data.

       EVP_KEYEXCH_get0_description() returns a description of the keyexch,
       meant for display and human consumption.  The description is at the
       discretion of the keyexch implementation.

       EVP_KEYEXCH_do_all_provided() traverses all key exchange
       implementations by all activated providers in the library context
       libctx, and for each of the implementations, calls fn with the
       implementation method and data as arguments.

       EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_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 exchange
       algorithm using EVP_PKEY_CTX_get_params(3) and
       EVP_PKEY_CTX_set_params(3).

RETURN VALUES
       EVP_KEYEXCH_fetch() returns a pointer to a EVP_KEYEXCH for success or
       NULL for failure.

       EVP_KEYEXCH_up_ref() returns 1 for success or 0 otherwise.

       EVP_KEYEXCH_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_KEYEXCH_is_a() returns 1 of exchange was identifiable, otherwise 0.

       EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_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 2019-2021 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_KEYEXCH_free(3)