.\" $OpenBSD: OPENSSL_config.3,v 1.16 2023/11/19 21:01:27 tb Exp $
.\" full merge up to: OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
.\"
.\" This file is a derived work.
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.\" Copyright (c) 2018 Ingo Schwarze <schwarze@openbsd.org>
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.\" The original file was written by Dr. Stephen Henson <steve@openssl.org>.
.\" Copyright (c) 2004 The OpenSSL Project.  All rights reserved.
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.Dd $Mdocdate: November 19 2023 $
.Dt OPENSSL_CONFIG 3
.Os
.Sh NAME
.Nm OPENSSL_config ,
.Nm OPENSSL_no_config
.Nd simple crypto and ssl library configuration
.Sh SYNOPSIS
.In openssl/conf.h
.Ft void
.Fo OPENSSL_config
.Fa "const char *appname"
.Fc
.Ft void
.Fn OPENSSL_no_config void
.Sh DESCRIPTION
.Fn OPENSSL_config
initializes the crypto library and calls
.Xr CONF_modules_load_file 3
with the standard configuration file and the given
.Fa appname .
If
.Fa appname
is
.Dv NULL ,
then the default name
.Sy openssl_conf
is used.
Any errors are ignored.
Further calls to
.Fn OPENSSL_config
have no effect.
.Pp
.Fn OPENSSL_no_config
suppresses the loading of the standard configuration file, so that any
future calls to
.Fn OPENSSL_config
or to
.Xr OPENSSL_init_crypto 3
will ensure the library is initialized but no configuration
file will be loaded.
.Pp
Calling these functions is optional.
All required initialization of the crypto libraries happens
automatically when needed.
.Pp
To use a non-standard configuration file, refer to
.Xr CONF_modules_load_file 3 .
.Pp
Internally,
.Fn OPENSSL_config
calls
.Xr OPENSSL_init_crypto 3
and
.Xr OPENSSL_load_builtin_modules 3 .
.Pp
If an application is compiled with the preprocessor symbol
.Dv OPENSSL_LOAD_CONF
#define'd,
.Xr OpenSSL_add_all_algorithms 3
automatically calls
.Fn OPENSSL_config .
.Pp
Applications should free up configuration at application closedown by
calling
.Xr CONF_modules_free 3 .
.Sh FILES
.Bl -tag -width /etc/ssl/openssl.cnf -compact
.It Pa /etc/ssl/openssl.cnf
standard configuration file
.El
.Sh SEE ALSO
.Xr CONF_modules_free 3 ,
.Xr CONF_modules_load_file 3 ,
.Xr crypto 3 ,
.Xr OPENSSL_load_builtin_modules 3 ,
.Xr OPENSSL_VERSION_NUMBER 3 ,
.Xr openssl.cnf 5 ,
.Xr x509v3.cnf 5
.Sh HISTORY
.Fn OPENSSL_config
and
.Fn OPENSSL_no_config
first appeared in OpenSSL 0.9.7 and have been available since
.Ox 3.2 .