doc/man3/EVP_KEYEXCH_free.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 EVP_KEYEXCH_fetch, EVP_KEYEXCH_free, EVP_KEYEXCH_up_ref, EVP_KEYEXCH_provider,
   6 EVP_KEYEXCH_is_a, EVP_KEYEXCH_do_all_provided,
   7 EVP_KEYEXCH_number, EVP_KEYEXCH_names_do_all,
   8 EVP_KEYEXCH_name, EVP_KEYEXCH_description,
   9 EVP_KEYEXCH_gettable_ctx_params, EVP_KEYEXCH_settable_ctx_params
  10 - Functions to manage EVP_KEYEXCH algorithm objects
  11
  12 =head1 SYNOPSIS
  13
  14  #include <openssl/evp.h>
  15
  16  EVP_KEYEXCH *EVP_KEYEXCH_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
  17                                 const char *properties);
  18  void EVP_KEYEXCH_free(EVP_KEYEXCH *exchange);
  19  int EVP_KEYEXCH_up_ref(EVP_KEYEXCH *exchange);
  20  OSSL_PROVIDER *EVP_KEYEXCH_provider(const EVP_KEYEXCH *exchange);
  21  int EVP_KEYEXCH_is_a(const EVP_KEYEXCH *exchange, const char *name);
  22  int EVP_KEYEXCH_number(const EVP_KEYEXCH *exchange);
  23  const char *EVP_KEYEXCH_name(const EVP_KEYEXCH *exchange);
  24  void EVP_KEYEXCH_do_all_provided(OSSL_LIB_CTX *libctx,
  25                                   void (*fn)(EVP_KEYEXCH *exchange, void *arg),
  26                                   void *arg);
  27  int EVP_KEYEXCH_names_do_all(const EVP_KEYEXCH *exchange,
  28                               void (*fn)(const char *name, void *data),
  29                               void *data);
  30  const char *EVP_KEYEXCH_description(const EVP_KEYEXCH *keyexch);
  31  const OSSL_PARAM *EVP_KEYEXCH_gettable_ctx_params(const EVP_KEYEXCH *keyexch);
  32  const OSSL_PARAM *EVP_KEYEXCH_settable_ctx_params(const EVP_KEYEXCH *keyexch);
  33
  34 =head1 DESCRIPTION
  35
  36 EVP_KEYEXCH_fetch() fetches the key exchange implementation for the given
  37 I<algorithm> from any provider offering it, within the criteria given
  38 by the I<properties>.
  39 See L<crypto(7)/ALGORITHM FETCHING> for further information.
  40
  41 The returned value must eventually be freed with EVP_KEYEXCH_free().
  42
  43 EVP_KEYEXCH_free() decrements the reference count for the B<EVP_KEYEXCH>
  44 structure. Typically this structure will have been obtained from an earlier call
  45 to EVP_KEYEXCH_fetch(). If the reference count drops to 0 then the
  46 structure is freed.
  47
  48 EVP_KEYEXCH_up_ref() increments the reference count for an B<EVP_KEYEXCH>
  49 structure.
  50
  51 EVP_KEYEXCH_provider() returns the provider that I<exchange> was fetched from.
  52
  53 EVP_KEYEXCH_is_a() checks if I<exchange> is an implementation of an
  54 algorithm that's identifiable with I<name>.
  55
  56 EVP_KEYEXCH_number() returns the internal dynamic number assigned to
  57 the I<exchange>.
  58
  59 EVP_KEYEXCH_name() returns the algorithm name from the provided
  60 implementation for the given I<exchange>. Note that the I<exchange> may have
  61 multiple synonyms associated with it. In this case the first name from the
  62 algorithm definition is returned. Ownership of the returned string is retained
  63 by the I<exchange> object and should not be freed by the caller.
  64
  65 EVP_KEYEXCH_names_do_all() traverses all names for the I<exchange>, and
  66 calls I<fn> with each name and I<data>.
  67
  68 EVP_KEYEXCH_description() returns a description of the I<keyexch>, meant for
  69 display and human consumption.  The description is at the discretion of the
  70 I<keyexch> implementation.
  71
  72 EVP_KEYEXCH_do_all_provided() traverses all key exchange implementations by
  73 all activated providers in the library context I<libctx>, and for each
  74 of the implementations, calls I<fn> with the implementation method and
  75 I<data> as arguments.
  76
  77 EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_settable_ctx_params() return
  78 a constant B<OSSL_PARAM> array that describes the names and types of key
  79 parameters that can be retrieved or set by a key exchange algorithm using
  80 L<EVP_PKEY_CTX_get_params(3)> and L<EVP_PKEY_CTX_set_params(3)>.
  81
  82 =head1 RETURN VALUES
  83
  84 EVP_KEYEXCH_fetch() returns a pointer to a B<EVP_KEYEXCH> for success
  85 or NULL for failure.
  86
  87 EVP_KEYEXCH_up_ref() returns 1 for success or 0 otherwise.
  88
  89 EVP_KEYEXCH_names_do_all() returns 1 if the callback was called for all
  90 names. A return value of 0 means that the callback was not called for any names.
  91
  92 EVP_KEYEXCH_is_a() returns 1 of I<exchange> was identifiable,
  93 otherwise 0.
  94
  95 EVP_KEYEXCH_number() returns an integer.
  96
  97 EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_settable_ctx_params() return
  98 a constant B<OSSL_PARAM> array or NULL on error.
  99
 100 =head1 SEE ALSO
 101
 102 L<crypto(7)/ALGORITHM FETCHING>, L<OSSL_PROVIDER(3)>
 103
 104 =head1 HISTORY
 105
 106 The functions described here were added in OpenSSL 3.0.
 107
 108 =head1 COPYRIGHT
 109
 110 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
 111
 112 Licensed under the Apache License 2.0 (the "License").  You may not use
 113 this file except in compliance with the License.  You can obtain a copy
 114 in the file LICENSE in the source distribution or at
 115 L<https://www.openssl.org/source/license.html>.
 116
 117 =cut