OSSL-GUIDE-INTRODUCTION(7ossl)

🌸 NAME 🌸

okay so bestie, welcome to ossl-guide-introduction — this is the OpenSSL Guide, and it's literally the introduction to OpenSSL. Manual page ossl-guide-introduction(7ossl), at your service 💅

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✨ WHAT IS OPENSSL? ✨

OpenSSL is a robust, commercial-grade, full-featured toolkit for general-purpose cryptography and secure communication. Like, the whole package. 🎀

Its features are made available via a command line application that lets users do all the cryptography-related things — generating keys, generating certificates, the works. On top of that, it supplies two libraries that application developers can use to implement cryptography-based capabilities and to securely communicate across a network. And finally, it's also got a set of providers that supply implementations of a broad set of cryptographic algorithms. It's giving full-stack, honestly. 👑

OpenSSL is fully open source. Version 3.0 and above are distributed under the Apache v2 license. periodt. 🌈

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🦋 GETTING AND INSTALLING OPENSSL 🦋

The OpenSSL Project develops and distributes the source code for OpenSSL. You can grab that source code from the OpenSSL website:

https://www.openssl.org/source

Many Operating Systems (notably Linux distributions) supply pre-built OpenSSL binaries either pre-installed or available via the package management system in use for that OS. So before you go attempting to build OpenSSL from source — bestie, please — check whether this already applies to you. 🙈

Some third parties also supply OpenSSL binaries (e.g. for Windows and some other platforms). The OpenSSL project maintains a list of these third parties here:

https://github.com/openssl/openssl/wiki/Binaries

🧚 Building from source

If you build and install OpenSSL from the source code, then you should download the appropriate files for the version you want to use from the link given above. Extract the contents of the tar.gz archive file that you downloaded into an appropriate directory. 📦

Inside that archive you'll find a file named INSTALL.md, which supplies detailed instructions on how to build and install OpenSSL from source. Make sure you read the contents of that file carefully in order to achieve a successful build — no cap, this part matters. 🔥

In the directory you'll also find a set of NOTES files that provide further platform-specific information. Make sure you carefully read the file appropriate to your platform. And as well as the platform-specific NOTES files, there's also a NOTES-PERL.md file that provides information about setting up Perl for use by the OpenSSL build system across multiple platforms. Slay, Perl. 🐪

⚠️ Sometimes you may want to build and install OpenSSL from source on a system which already has a pre-built version of OpenSSL installed on it via the Operating System package management system (for example, if you want to use a newer version of OpenSSL than the one supplied by your Operating System). In this case it is strongly recommended to install OpenSSL to a different location than where the pre-built version is installed. You should never replace the pre-built version with a different version — this may break your system. Like, genuinely. Do not do it. 💀

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🎀 CONTENTS OF THE OPENSSL GUIDE 🎀

The OpenSSL Guide is a series of documentation pages (starting with this one) that introduce some of the main concepts in OpenSSL. You can either read the guide end-to-end in order, or alternatively just skip to the parts most applicable to your use case. Note however that later pages may depend on and assume knowledge from earlier pages — so the skip-around route is valid but lowkey risky. 😭

The pages in the guide are as follows:

• ossl-guide-libraries-introduction(7): An introduction to the OpenSSL libraries
• ossl-guide-libcrypto-introduction(7): An introduction to libcrypto
• ossl-guide-libssl-introduction(7): An introduction to libssl
• ossl-guide-tls-introduction(7): An introduction to SSL/TLS in OpenSSL
• ossl-guide-tls-client-block(7): Writing a simple blocking TLS client
• ossl-guide-tls-client-non-block(7): Writing a simple nonblocking TLS client
• ossl-guide-tls-server-block(7): Writing a simple blocking TLS server
• ossl-guide-quic-introduction(7): An introduction to QUIC in OpenSSL
• ossl-guide-quic-client-block(7): Writing a simple blocking QUIC client
• ossl-guide-quic-server-block(7): Writing a simple blocking QUIC server
• ossl-guide-quic-multi-stream(7): Writing a simple multi-stream QUIC client
• ossl-guide-quic-server-non-block(7): Writing a simple nonblocking QUIC server
• ossl-guide-quic-client-non-block(7): Writing a simple nonblocking QUIC client
• ossl-guide-migration(7): Migrating from older OpenSSL versions

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💖 COPYRIGHT 💖

Copyright 2023-2025 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 page, bestie 🫶 this was version 3.5.9, dated 2026-09-29 — iconic, honestly. go build something secure 💜