NAME

       ossl-guide-introduction - OpenSSL Guide: An introduction to OpenSSL

WHAT IS OPENSSL?

       OpenSSL is a robust, commercial-grade, full-featured toolkit for general-purpose
       cryptography and secure communication. Its features are made available via a command line
       application that enables users to perform various cryptography related functions such as
       generating keys and certificates. Additionally it supplies two libraries that application
       developers can use to implement cryptography based capabilities and to securely
       communicate across a network.  Finally, it also has a set of providers that supply
       implementations of a broad set of cryptographic algorithms.

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

GETTING AND INSTALLING OPENSSL

       The OpenSSL Project develops and distributes the source code for OpenSSL. You can obtain
       that source code via 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. It
       is worth checking whether this applies to you before attempting to build OpenSSL from the
       source code.

       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 at
       <https://wiki.openssl.org/index.php/Binaries>.

       If you build and install OpenSSL from the source code then you should download the
       appropriate files for the version that 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 will find a file named INSTALL.md which will supply 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. In the directory
       you will also find a set of NOTES files that provide further platform specific
       information.  Make sure you carefully read the file appropriate to your platform. As well
       as the platform specific NOTES files there is also a NOTES-PERL.md file that provides
       information about setting up Perl for use by the OpenSSL build system across multiple
       platforms.

       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 as this may break your
       system.

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. The guide can either be read end-to-end in
       order, or alternatively you can simply skip to the parts most applicable to your use case.
       Note however that later pages may depend on and assume knowledge from earlier pages.

       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-multi-stream(7): Writing a simple multi-stream QUIC client
       ossl-guide-quic-client-non-block(7): Writing a simple nonblocking QUIC client
       ossl-guide-migration(7): Migrating from older OpenSSL versions

COPYRIGHT

       Copyright 2023-2024 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>.