doc/man3/EVP_KEYEXCH_free.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 EVP_KEYEXCH_fetch, EVP_KEYEXCH_free, EVP_KEYEXCH_up_ref,
   6 EVP_KEYEXCH_get0_provider, EVP_KEYEXCH_is_a, EVP_KEYEXCH_do_all_provided,
   7 EVP_KEYEXCH_names_do_all, EVP_KEYEXCH_get0_name, EVP_KEYEXCH_get0_description,
   8 EVP_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
  34 EVP_KEYEXCH_fetch() fetches the key exchange implementation for the given
  35 I<algorithm> from any provider offering it, within the criteria given
  36 by the I<properties>.
  37 See L<crypto(7)/ALGORITHM FETCHING> for further information.
  38
  39 The returned value must eventually be freed with EVP_KEYEXCH_free().
  40
  41 EVP_KEYEXCH_free() decrements the reference count for the B<EVP_KEYEXCH>
  42 structure. Typically this structure will have been obtained from an earlier call
  43 to EVP_KEYEXCH_fetch(). If the reference count drops to 0 then the
  44 structure is freed.
  45
  46 EVP_KEYEXCH_up_ref() increments the reference count for an B<EVP_KEYEXCH>
  47 structure.
  48
  49 EVP_KEYEXCH_get0_provider() returns the provider that I<exchange> was
  50 fetched from.
  51
  52 EVP_KEYEXCH_is_a() checks if I<exchange> is an implementation of an
  53 algorithm that's identifiable with I<name>.
  54
  55 EVP_KEYEXCH_get0_name() returns the algorithm name from the provided
  56 implementation for the given I<exchange>. Note that the I<exchange> may have
  57 multiple synonyms associated with it. In this case the first name from the
  58 algorithm definition is returned. Ownership of the returned string is retained
  59 by the I<exchange> object and should not be freed by the caller.
  60
  61 EVP_KEYEXCH_names_do_all() traverses all names for the I<exchange>, and
  62 calls I<fn> with each name and I<data>.
  63
  64 EVP_KEYEXCH_get0_description() returns a description of the I<keyexch>, meant
  65 for display and human consumption.  The description is at the discretion of
  66 the I<keyexch> implementation.
  67
  68 EVP_KEYEXCH_do_all_provided() traverses all key exchange implementations by
  69 all activated providers in the library context I<libctx>, and for each
  70 of the implementations, calls I<fn> with the implementation method and
  71 I<data> as arguments.
  72
  73 EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_settable_ctx_params() return
  74 a constant L<OSSL_PARAM(3)> array that describes the names and types of key
  75 parameters that can be retrieved or set by a key exchange algorithm using
  76 L<EVP_PKEY_CTX_get_params(3)> and L<EVP_PKEY_CTX_set_params(3)>.
  77
  78 =head1 RETURN VALUES
  79
  80 EVP_KEYEXCH_fetch() returns a pointer to a B<EVP_KEYEXCH> for success
  81 or NULL for failure.
  82
  83 EVP_KEYEXCH_up_ref() returns 1 for success or 0 otherwise.
  84
  85 EVP_KEYEXCH_names_do_all() returns 1 if the callback was called for all
  86 names. A return value of 0 means that the callback was not called for any names.
  87
  88 EVP_KEYEXCH_is_a() returns 1 of I<exchange> was identifiable,
  89 otherwise 0.
  90
  91 EVP_KEYEXCH_gettable_ctx_params() and EVP_KEYEXCH_settable_ctx_params() return
  92 a constant L<OSSL_PARAM(3)> array or NULL on error.
  93
  94 =head1 SEE ALSO
  95
  96 L<crypto(7)/ALGORITHM FETCHING>, L<OSSL_PROVIDER(3)>
  97
  98 =head1 HISTORY
  99
 100 The functions described here were added in OpenSSL 3.0.
 101
 102 =head1 COPYRIGHT
 103
 104 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
 105
 106 Licensed under the Apache License 2.0 (the "License").  You may not use
 107 this file except in compliance with the License.  You can obtain a copy
 108 in the file LICENSE in the source distribution or at
 109 L<https://www.openssl.org/source/license.html>.
 110
 111 =cut