openssl-prebuild/linux_amd64/ssl/share/man/man3/EVP_SIGNATURE_free.3

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.IX Title "EVP_SIGNATURE_FREE 3"
.TH EVP_SIGNATURE_FREE 3 "2020-03-02" "3.0.0-dev" "OpenSSL"
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.nh
.SH "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
\&\- Functions to manage EVP_SIGNATURE algorithm objects
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/evp.h>
\&
\& EVP_SIGNATURE *EVP_SIGNATURE_fetch(OPENSSL_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(OPENSSL_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);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fIEVP_SIGNATURE_fetch()\fR fetches the implementation for the given
\&\fBalgorithm\fR from any provider offering it, within the criteria given
by the \fBproperties\fR.
The algorithm will be one offering functions for performing signature related
tasks such as signing and verifying.
See \*(L"Fetching algorithms\*(R" in \fIprovider\fR\|(7) for further information.
.PP
The returned value must eventually be freed with \fIEVP_SIGNATURE_free()\fR.
.PP
\&\fIEVP_SIGNATURE_free()\fR decrements the reference count for the \fB\s-1EVP_SIGNATURE\s0\fR
structure. Typically this structure will have been obtained from an earlier call
to \fIEVP_SIGNATURE_fetch()\fR. If the reference count drops to 0 then the
structure is freed.
.PP
\&\fIEVP_SIGNATURE_up_ref()\fR increments the reference count for an \fB\s-1EVP_SIGNATURE\s0\fR
structure.
.PP
\&\fIEVP_SIGNATURE_is_a()\fR returns 1 if \fIsignature\fR is an implementation of an
algorithm that's identifiable with \fIname\fR, otherwise 0.
.PP
\&\fIEVP_SIGNATURE_provider()\fR returns the provider that \fIsignature\fR was fetched from.
.PP
\&\fIEVP_SIGNATURE_do_all_provided()\fR traverses all \s-1SIGNATURE\s0 implemented by all
activated roviders in the given library context \fIlibctx\fR, and for each of the
implementations, calls the given function \fIfn\fR with the implementation method
and the given \fIarg\fR as argument.
.PP
\&\fIEVP_SIGNATURE_number()\fR returns the internal dynamic number assigned to
\&\fIsignature\fR.
.PP
\&\fIEVP_SIGNATURE_names_do_all()\fR traverses all names for \fIsignature\fR, and calls
\&\fIfn\fR with each name and \fIdata\fR.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIEVP_SIGNATURE_fetch()\fR returns a pointer to an \fB\s-1EVP_SIGNATURE\s0\fR for success
or \fB\s-1NULL\s0\fR for failure.
.PP
\&\fIEVP_SIGNATURE_up_ref()\fR returns 1 for success or 0 otherwise.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\*(L"Fetching algorithms\*(R" in \fIprovider\fR\|(7), \s-1\fIOSSL_PROVIDER\s0\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
The functions described here were added in OpenSSL 3.0.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.