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.
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 2019-2021 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