1=pod 2 3=head1 NAME 4 5EVP_SIGNATURE, 6EVP_SIGNATURE_fetch, EVP_SIGNATURE_free, EVP_SIGNATURE_up_ref, 7EVP_SIGNATURE_is_a, EVP_SIGNATURE_get0_provider, 8EVP_SIGNATURE_do_all_provided, EVP_SIGNATURE_names_do_all, 9EVP_SIGNATURE_get0_name, EVP_SIGNATURE_get0_description, 10EVP_SIGNATURE_gettable_ctx_params, EVP_SIGNATURE_settable_ctx_params 11- Functions to manage EVP_SIGNATURE algorithm objects 12 13=head1 SYNOPSIS 14 15 #include <openssl/evp.h> 16 17 typedef struct evp_signature_st EVP_SIGNATURE; 18 19 EVP_SIGNATURE *EVP_SIGNATURE_fetch(OSSL_LIB_CTX *ctx, const char *algorithm, 20 const char *properties); 21 void EVP_SIGNATURE_free(EVP_SIGNATURE *signature); 22 int EVP_SIGNATURE_up_ref(EVP_SIGNATURE *signature); 23 const char *EVP_SIGNATURE_get0_name(const EVP_SIGNATURE *signature); 24 int EVP_SIGNATURE_is_a(const EVP_SIGNATURE *signature, const char *name); 25 OSSL_PROVIDER *EVP_SIGNATURE_get0_provider(const EVP_SIGNATURE *signature); 26 void EVP_SIGNATURE_do_all_provided(OSSL_LIB_CTX *libctx, 27 void (*fn)(EVP_SIGNATURE *signature, 28 void *arg), 29 void *arg); 30 int EVP_SIGNATURE_names_do_all(const EVP_SIGNATURE *signature, 31 void (*fn)(const char *name, void *data), 32 void *data); 33 const char *EVP_SIGNATURE_get0_name(const EVP_SIGNATURE *signature); 34 const char *EVP_SIGNATURE_get0_description(const EVP_SIGNATURE *signature); 35 const OSSL_PARAM *EVP_SIGNATURE_gettable_ctx_params(const EVP_SIGNATURE *sig); 36 const OSSL_PARAM *EVP_SIGNATURE_settable_ctx_params(const EVP_SIGNATURE *sig); 37 38=head1 DESCRIPTION 39 40EVP_SIGNATURE_fetch() fetches the implementation for the given 41B<algorithm> from any provider offering it, within the criteria given 42by the B<properties>. 43The algorithm will be one offering functions for performing signature related 44tasks such as signing and verifying. 45See L<crypto(7)/ALGORITHM FETCHING> for further information. 46 47The returned value must eventually be freed with EVP_SIGNATURE_free(). 48 49EVP_SIGNATURE_free() decrements the reference count for the B<EVP_SIGNATURE> 50structure. Typically this structure will have been obtained from an earlier call 51to EVP_SIGNATURE_fetch(). If the reference count drops to 0 then the 52structure is freed. If the argument is NULL, nothing is done. 53 54EVP_SIGNATURE_up_ref() increments the reference count for an B<EVP_SIGNATURE> 55structure. 56 57EVP_SIGNATURE_is_a() returns 1 if I<signature> is an implementation of an 58algorithm that's identifiable with I<name>, otherwise 0. 59 60EVP_SIGNATURE_get0_provider() returns the provider that I<signature> was 61fetched from. 62 63EVP_SIGNATURE_do_all_provided() traverses all SIGNATURE implemented by all 64activated providers in the given library context I<libctx>, and for each of the 65implementations, calls the given function I<fn> with the implementation method 66and the given I<arg> as argument. 67 68EVP_SIGNATURE_get0_name() returns the algorithm name from the provided 69implementation for the given I<signature>. Note that the I<signature> may have 70multiple synonyms associated with it. In this case the first name from the 71algorithm definition is returned. Ownership of the returned string is retained 72by the I<signature> object and should not be freed by the caller. 73 74EVP_SIGNATURE_names_do_all() traverses all names for I<signature>, and calls 75I<fn> with each name and I<data>. 76 77EVP_SIGNATURE_get0_description() returns a description of the I<signature>, 78meant for display and human consumption. The description is at the 79discretion of the I<signature> implementation. 80 81EVP_SIGNATURE_gettable_ctx_params() and EVP_SIGNATURE_settable_ctx_params() 82return a constant L<OSSL_PARAM(3)> array that describes the names and types of key 83parameters that can be retrieved or set by a signature algorithm using 84L<EVP_PKEY_CTX_get_params(3)> and L<EVP_PKEY_CTX_set_params(3)>. 85 86=head1 RETURN VALUES 87 88EVP_SIGNATURE_fetch() returns a pointer to an B<EVP_SIGNATURE> for success 89or B<NULL> for failure. 90 91EVP_SIGNATURE_up_ref() returns 1 for success or 0 otherwise. 92 93EVP_SIGNATURE_names_do_all() returns 1 if the callback was called for all names. 94A return value of 0 means that the callback was not called for any names. 95 96EVP_SIGNATURE_gettable_ctx_params() and EVP_SIGNATURE_settable_ctx_params() 97return a constant L<OSSL_PARAM(3)> array or NULL on error. 98 99=head1 SEE ALSO 100 101L<crypto(7)/ALGORITHM FETCHING>, L<OSSL_PROVIDER(3)> 102 103=head1 HISTORY 104 105The functions described here were added in OpenSSL 3.0. 106 107=head1 COPYRIGHT 108 109Copyright 2019-2024 The OpenSSL Project Authors. All Rights Reserved. 110 111Licensed under the Apache License 2.0 (the "License"). You may not use 112this file except in compliance with the License. You can obtain a copy 113in the file LICENSE in the source distribution or at 114L<https://www.openssl.org/source/license.html>. 115 116=cut 117