OPENSSL_CONFIG(3ossl)

💖 OPENSSL_CONFIG 💖

okay bestie, gather round, because we're talking about OPENSSL_config and OPENSSL_no_config — the "simple OpenSSL configuration functions" from the OpenSSL manual, page OPENSSL_CONFIG(3ossl). yes they're deprecated. no we're not ignoring them. let's get into it 🎀

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✨ SYNOPSIS ✨

#include <openssl/conf.h>

🚨 bestie alert 🚨 the following functions have been deprecated since OpenSSL 1.1.0, and can be hidden entirely by defining OPENSSL_API_COMPAT with a suitable version value — go peek at openssl_user_macros(7) for the deets.

void OPENSSL_config(const char *appname);
void OPENSSL_no_config(void);

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🌸 DESCRIPTION 🌸

okay so OPENSSL_config() configures OpenSSL using the standard openssl.cnf and reads from the application section appname. and if appname is NULL? then it just uses the default section, openssl_conf. iconic default behavior honestly. 💅

and here's the tea: errors are silently ignored. like, fully silent. not a peep. 😭 and calling it multiple times has no effect — multiple calls have no effect, periodt.

then we've got OPENSSL_no_config() which disables configuration. and if you call it before OPENSSL_config(), no configuration takes place at all. gone. nada. 🙈

one more thing — if the application is built with OPENSSL_LOAD_CONF defined, then a call to OpenSSL_add_all_algorithms() will implicitly call OPENSSL_config() first. sneaky little chain reaction, love that for it ✨

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👑 NOTES 👑

OPENSSL_config() is designed to be a very simple "call it and forget it" function. it's lowkey giving set-it-and-forget-it energy. and honestly? it is however much better than nothing. 🫶

but if your application needs finer control over its configuration functionality, you should use the configuration functions such as CONF_modules_load() directly. this function is deprecated and its use should be avoided. like, avoid it avoid it. instead, applications should call CONF_modules_load() during initialization — that is, before starting any threads. no cap. 🧵❌

so why is calling the OpenSSL configuration routines advisable at all? several reasons, bestie. for example, to load dynamic ENGINEs from shared libraries (DSOs). 🔥 however — very few applications currently support the control interface, and so very few can load and use dynamic ENGINEs. equally, in future more sophisticated ENGINEs will require certain control operations to customize them. and here's the slay: if an application calls OPENSSL_config(), it doesn't need to know or care about ENGINE control operations, because they can be performed by editing a configuration file. main character energy fr fr 💜

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🌈 ENVIRONMENT 🌈

• OPENSSL_CONF — the path to the config file. 👀 but heads up: ignored in set-user-ID and set-group-ID programs.

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💀 RETURN VALUES 💀

neither OPENSSL_config() nor OPENSSL_no_config() return a value. that's it. that's the whole section. void behavior, zero notes. 💅

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🦋 SEE ALSO 🦋

• config(5)
• CONF_modules_load_file(3)

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⭐ HISTORY ⭐

the OPENSSL_no_config() and OPENSSL_config() functions were deprecated in OpenSSL 1.1.0 by OPENSSL_init_crypto(). rest in peace to a real one 🕊️

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🎀 COPYRIGHT 🎀

Copyright 2004-2020 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 <https://www.openssl.org/source/license.html>.

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and that's the whole vibe check bestie 💖 this was version 3.5.9, dated 2026-09-29, from the OpenSSL girlies themselves. stay deprecated, stay iconic, mwah 💋🌸