1=pod 2 3=head1 NAME 4 5EVP_KEYEXCH_fetch, EVP_KEYEXCH_free, EVP_KEYEXCH_up_ref, 6EVP_KEYEXCH_get0_provider, EVP_KEYEXCH_is_a, EVP_KEYEXCH_do_all_provided, 7EVP_KEYEXCH_names_do_all, EVP_KEYEXCH_get0_name, EVP_KEYEXCH_get0_description, 8EVP_KEYEXCH_gettable_ctx_params, EVP_KEYEXCH_settable_ctx_params 9- Functions to manage EVP_KEYEXCH algorithm objects 10 11=head1 SYNOPSIS 12 13 #include <openssl/evp.h> 14 15 EVP_KEYEXCH *EVP_KEYEXCH_fetch(OSSL_LIB_CTX *ctx, const char *algorithm, 16 const char *properties); 17 void EVP_KEYEXCH_free(EVP_KEYEXCH *exchange); 18 int EVP_KEYEXCH_up_ref(EVP_KEYEXCH *exchange); 19 OSSL_PROVIDER *EVP_KEYEXCH_get0_provider(const EVP_KEYEXCH *exchange); 20 int EVP_KEYEXCH_is_a(const EVP_KEYEXCH *exchange, const char *name); 21 const char *EVP_KEYEXCH_get0_name(const EVP_KEYEXCH *exchange); 22 void EVP_KEYEXCH_do_all_provided(OSSL_LIB_CTX *libctx, 23 void (*fn)(EVP_KEYEXCH *exchange, void *arg), 24 void *arg); 25 int EVP_KEYEXCH_names_do_all(const EVP_KEYEXCH *exchange, 26 void (*fn)(const char *name, void *data), 27 void *data); 28 const char *EVP_KEYEXCH_get0_description(const EVP_KEYEXCH *keyexch); 29 const OSSL_PARAM *EVP_KEYEXCH_gettable_ctx_params(const EVP_KEYEXCH *keyexch); 30 const OSSL_PARAM *EVP_KEYEXCH_settable_ctx_params(const EVP_KEYEXCH *keyexch); 31 32=head1 DESCRIPTION 33 34EVP_KEYEXCH_fetch() fetches the key exchange implementation for the given 35I<algorithm> from any provider offering it, within the criteria given 36by the I<properties>. 37See L<crypto(7)/ALGORITHM FETCHING> for further information. 38 39The returned value must eventually be freed with EVP_KEYEXCH_free(). 40 41EVP_KEYEXCH_free() decrements the reference count for the B<EVP_KEYEXCH> 42structure. Typically this structure will have been obtained from an earlier call 43to EVP_KEYEXCH_fetch(). If the reference count drops to 0 then the 44structure is freed. If the argument is NULL, nothing is done. 45 46EVP_KEYEXCH_up_ref() increments the reference count for an B<EVP_KEYEXCH> 47structure. 48 49EVP_KEYEXCH_get0_provider() returns the provider that I<exchange> was 50fetched from. 51 52EVP_KEYEXCH_is_a() checks if I<exchange> is an implementation of an 53algorithm that's identifiable with I<name>. 54 55EVP_KEYEXCH_get0_name() returns the algorithm name from the provided 56implementation for the given I<exchange>. Note that the I<exchange> may have 57multiple synonyms associated with it. In this case the first name from the 58algorithm definition is returned. Ownership of the returned string is retained 59by the I<exchange> object and should not be freed by the caller. 60 61EVP_KEYEXCH_names_do_all() traverses all names for the I<exchange>, and 62calls I<fn> with each name and I<data>. 63 64EVP_KEYEXCH_get0_description() returns a description of the I<keyexch>, meant 65for display and human consumption. The description is at the discretion of 66the I<keyexch> implementation. 67 68EVP_KEYEXCH_do_all_provided() traverses all key exchange implementations by 69all activated providers in the library context I<libctx>, and for each 70of the implementations, calls I<fn> with the implementation method and 71I<data> as arguments. 72 73EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_settable_ctx_params() return 74a constant L<OSSL_PARAM(3)> array that describes the names and types of key 75parameters that can be retrieved or set by a key exchange algorithm using 76L<EVP_PKEY_CTX_get_params(3)> and L<EVP_PKEY_CTX_set_params(3)>. 77 78=head1 RETURN VALUES 79 80EVP_KEYEXCH_fetch() returns a pointer to a B<EVP_KEYEXCH> for success 81or NULL for failure. 82 83EVP_KEYEXCH_up_ref() returns 1 for success or 0 otherwise. 84 85EVP_KEYEXCH_names_do_all() returns 1 if the callback was called for all 86names. A return value of 0 means that the callback was not called for any names. 87 88EVP_KEYEXCH_is_a() returns 1 of I<exchange> was identifiable, 89otherwise 0. 90 91EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_settable_ctx_params() return 92a constant L<OSSL_PARAM(3)> array or NULL on error. 93 94=head1 SEE ALSO 95 96L<crypto(7)/ALGORITHM FETCHING>, L<OSSL_PROVIDER(3)> 97 98=head1 HISTORY 99 100The functions described here were added in OpenSSL 3.0. 101 102=head1 COPYRIGHT 103 104Copyright 2019-2024 The OpenSSL Project Authors. All Rights Reserved. 105 106Licensed under the Apache License 2.0 (the "License"). You may not use 107this file except in compliance with the License. You can obtain a copy 108in the file LICENSE in the source distribution or at 109L<https://www.openssl.org/source/license.html>. 110 111=cut 112