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- =pod
- =head1 NAME
- EVP_SIGNATURE_fetch, EVP_SIGNATURE_free, EVP_SIGNATURE_up_ref,
- EVP_SIGNATURE_number, EVP_SIGNATURE_is_a, EVP_SIGNATURE_provider,
- EVP_SIGNATURE_do_all_provided, EVP_SIGNATURE_names_do_all,
- EVP_SIGNATURE_gettable_ctx_params, EVP_SIGNATURE_settable_ctx_params
- - Functions to manage EVP_SIGNATURE algorithm objects
- =head1 SYNOPSIS
- #include <openssl/evp.h>
- EVP_SIGNATURE *EVP_SIGNATURE_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
- const char *properties);
- void EVP_SIGNATURE_free(EVP_SIGNATURE *signature);
- int EVP_SIGNATURE_up_ref(EVP_SIGNATURE *signature);
- int EVP_SIGNATURE_number(const EVP_SIGNATURE *signature);
- int EVP_SIGNATURE_is_a(const EVP_SIGNATURE *signature, const char *name);
- OSSL_PROVIDER *EVP_SIGNATURE_provider(const EVP_SIGNATURE *signature);
- void EVP_SIGNATURE_do_all_provided(OSSL_LIB_CTX *libctx,
- void (*fn)(EVP_SIGNATURE *signature,
- void *arg),
- void *arg);
- void EVP_SIGNATURE_names_do_all(const EVP_SIGNATURE *signature,
- void (*fn)(const char *name, void *data),
- void *data);
- const OSSL_PARAM *EVP_SIGNATURE_gettable_ctx_params(const EVP_SIGNATURE *sig);
- const OSSL_PARAM *EVP_SIGNATURE_settable_ctx_params(const EVP_SIGNATURE *sig);
- =head1 DESCRIPTION
- EVP_SIGNATURE_fetch() fetches the implementation for the given
- B<algorithm> from any provider offering it, within the criteria given
- by the B<properties>.
- The algorithm will be one offering functions for performing signature related
- tasks such as signing and verifying.
- See L<provider(7)/Fetching algorithms> for further information.
- The returned value must eventually be freed with EVP_SIGNATURE_free().
- EVP_SIGNATURE_free() decrements the reference count for the B<EVP_SIGNATURE>
- structure. Typically this structure will have been obtained from an earlier call
- to EVP_SIGNATURE_fetch(). If the reference count drops to 0 then the
- structure is freed.
- EVP_SIGNATURE_up_ref() increments the reference count for an B<EVP_SIGNATURE>
- structure.
- EVP_SIGNATURE_is_a() returns 1 if I<signature> is an implementation of an
- algorithm that's identifiable with I<name>, otherwise 0.
- EVP_SIGNATURE_provider() returns the provider that I<signature> was fetched from.
- EVP_SIGNATURE_do_all_provided() traverses all SIGNATURE implemented by all
- activated roviders in the given library context I<libctx>, and for each of the
- implementations, calls the given function I<fn> with the implementation method
- and the given I<arg> as argument.
- EVP_SIGNATURE_number() returns the internal dynamic number assigned to
- I<signature>.
- EVP_SIGNATURE_names_do_all() traverses all names for I<signature>, and calls
- I<fn> with each name and I<data>.
- EVP_SIGNATURE_gettable_ctx_params() and EVP_SIGNATURE_settable_ctx_params()
- return a constant B<OSSL_PARAM> array that describes the names and types of key
- parameters that can be retrieved or set by a signature algorithm using
- L<EVP_PKEY_CTX_get_params(3)> and L<EVP_PKEY_CTX_set_params(3)>.
- =head1 RETURN VALUES
- EVP_SIGNATURE_fetch() returns a pointer to an B<EVP_SIGNATURE> for success
- or B<NULL> for failure.
- EVP_SIGNATURE_up_ref() returns 1 for success or 0 otherwise.
- EVP_SIGNATURE_gettable_ctx_params() and EVP_SIGNATURE_settable_ctx_params()
- return a constant B<OSSL_PARAM> array or NULL on error.
- =head1 SEE ALSO
- L<provider(7)/Fetching algorithms>, L<OSSL_PROVIDER(3)>
- =head1 HISTORY
- The functions described here were added in OpenSSL 3.0.
- =head1 COPYRIGHT
- Copyright 2019-2020 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
- L<https://www.openssl.org/source/license.html>.
- =cut
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