A local copy of OpenSSL from GitHub
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
Tanzinul Islam 5fee3fe276 Support DLL builds + Fix C RTL variants 2 years ago
.github Github workflows: re-implement a no-shared build 1 year ago
Configurations Support DLL builds + Fix C RTL variants 1 year ago
VMS VMS documentation fixes 1 year ago
apps Add "origin" field to EVP_CIPHER, EVP_MD 1 year ago
crypto Support DLL builds + Fix C RTL variants 1 year ago
demos Fix typo in aesccm.c 1 year ago
dev Update copyright year 1 year ago
doc Add DHX FIPS 186-4 domain parameter validation example 1 year ago
engines Add "origin" field to EVP_CIPHER, EVP_MD 1 year ago
external/perl Update the bundled external perl module Text-Template to version 1.56 3 years ago
fuzz Add a local perl module to get year last changed 1 year ago
gost-engine@28a0a19354 CI: add job with external tests 1 year ago
include Add "origin" field to EVP_CIPHER, EVP_MD 1 year ago
krb5@890ca2f401 Update the krb5 submodule 3 years ago
ms Unify all assembler file generators 3 years ago
os-dep Move Haiku configuration to separate config file to denote 6 years ago
providers Do IV reset also for DES and 3DES implementations 1 year ago
pyca-cryptography@e09cd90f77 CI: add job with external tests 1 year ago
ssl Add "origin" field to EVP_CIPHER, EVP_MD 1 year ago
test Add test for the IV handling of DES based ciphers 1 year ago
tools Update copyright year 1 year ago
util Add "origin" field to EVP_CIPHER, EVP_MD 1 year ago
.gitattributes Remove the external BoringSSL test 1 year ago
.gitignore Resurrect and modernize C++Builder config 1 year ago
.gitmodules Remove the external BoringSSL test 1 year ago
.travis-apt-pin.preferences Fix travis clang-3.9 builds 5 years ago
.travis-create-release.sh Remove all 'make dist' artifacts 4 years ago
ACKNOWLEDGEMENTS.md Fix issues reported by markdownlint 2 years ago
AUTHORS.md Add some missing committers to the AUTHORS list 1 year ago
CHANGES.md Change the default MANSUFFIX 1 year ago
CONTRIBUTING.md Drop Travis 1 year ago
Configure Configure: Check if 128-bit integers are supported by compiler 1 year ago
FAQ.md doc: introduce some minimalistic markdown without essential changes 2 years ago
HACKING.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
INSTALL.md Moved build instructions from the man page 1 year ago
LICENSE.txt Rename NOTES*, README*, VERSION, HACKING, LICENSE to .md or .txt 2 years ago
NEWS.md Update KTLS documentation 1 year ago
NOTES-ANDROID.md Unify the markdown links to the NOTES and README files 1 year ago
NOTES-DJGPP.md Unify the markdown links to the NOTES and README files 1 year ago
NOTES-NONSTOP.md Rewrite the HPE NonStop Notes file in Markdown with more explanations. 2 years ago
NOTES-PERL.md Reformat some NOTES and README files 1 year ago
NOTES-UNIX.md Unify the markdown links to the NOTES and README files 1 year ago
NOTES-VALGRIND.md Unify the markdown links to the NOTES and README files 1 year ago
NOTES-VMS.md Reformat some NOTES and README files 1 year ago
NOTES-WINDOWS.md Support DLL builds + Fix C RTL variants 1 year ago
README-ENGINES.md README-ENGINES: fix the link to the provider API README 1 year ago
README-FIPS.md Update README-FIPS.md 1 year ago
README-PROVIDERS.md Add a skeleton README-PROVIDERS file 1 year ago
README.md Unify the markdown links to the NOTES and README files 1 year ago
SUPPORT.md Fix SUPPORT.md for better readability 2 years ago
VERSION.dat Prepare for 3.0 alpha 15 1 year ago
appveyor.yml appveyor.yml: clarify conditions for building the plain configuration 1 year ago
build.info Configuration: ensure that 'no-tests' works correctly 1 year ago
config config: Turn into a simple wrapper 2 years ago
config.com Update copyright year 2 years ago
configdata.pm.in configdata.pm.in, util/dofile.pl: Make a HERE document stricter. 2 years ago
e_os.h Update copyright year 1 year ago


Welcome to the OpenSSL Project

openssl logo

github actions ci badge appveyor badge

OpenSSL is a robust, commercial-grade, full-featured Open Source Toolkit for the Transport Layer Security (TLS) protocol formerly known as the Secure Sockets Layer (SSL) protocol. The protocol implementation is based on a full-strength general purpose cryptographic library, which can also be used stand-alone.

OpenSSL is descended from the SSLeay library developed by Eric A. Young and Tim J. Hudson.

The official Home Page of the OpenSSL Project is www.openssl.org.

Table of Contents


The OpenSSL toolkit includes:

  • libssl an implementation of all TLS protocol versions up to TLSv1.3 (RFC 8446).

  • libcrypto a full-strength general purpose cryptographic library. It constitutes the basis of the TLS implementation, but can also be used independently.

  • openssl the OpenSSL command line tool, a swiss army knife for cryptographic tasks, testing and analyzing. It can be used for

    • creation of key parameters
    • creation of X.509 certificates, CSRs and CRLs
    • calculation of message digests
    • encryption and decryption
    • SSL/TLS client and server tests
    • handling of S/MIME signed or encrypted mail
    • and more...


For Production Use

Source code tarballs of the official releases can be downloaded from www.openssl.org/source. The OpenSSL project does not distribute the toolkit in binary form.

However, for a large variety of operating systems precompiled versions of the OpenSSL toolkit are available. In particular on Linux and other Unix operating systems it is normally recommended to link against the precompiled shared libraries provided by the distributor or vendor.

For Testing and Development

Although testing and development could in theory also be done using the source tarballs, having a local copy of the git repository with the entire project history gives you much more insight into the code base.

The official OpenSSL Git Repository is located at git.openssl.org. There is a GitHub mirror of the repository at github.com/openssl/openssl, which is updated automatically from the former on every commit.

A local copy of the Git Repository can be obtained by cloning it from the original OpenSSL repository using

git clone git://git.openssl.org/openssl.git

or from the GitHub mirror using

git clone https://github.com/openssl/openssl.git

If you intend to contribute to OpenSSL, either to fix bugs or contribute new features, you need to fork the OpenSSL repository openssl/openssl on GitHub and clone your public fork instead.

git clone https://github.com/yourname/openssl.git

This is necessary, because all development of OpenSSL nowadays is done via GitHub pull requests. For more details, see Contributing.

Build and Install

After obtaining the Source, have a look at the INSTALL file for detailed instructions about building and installing OpenSSL. For some platforms, the installation instructions are amended by a platform specific document.

Specific notes on upgrading to OpenSSL 3.0 from previous versions, as well as known issues are available on the OpenSSL 3.0 Wiki page.


Manual Pages

The manual pages for the master branch and all current stable releases are available online.


There is a Wiki at wiki.openssl.org which is currently not very active. It contains a lot of useful information, not all of which is up to date.


OpenSSL is licensed under the Apache License 2.0, which means that you are free to get and use it for commercial and non-commercial purposes as long as you fulfill its conditions.

See the LICENSE.txt file for more details.


There are various ways to get in touch. The correct channel depends on your requirement. see the SUPPORT file for more details.


If you are interested and willing to contribute to the OpenSSL project, please take a look at the CONTRIBUTING file.


A number of nations restrict the use or export of cryptography. If you are potentially subject to such restrictions you should seek legal advice before attempting to develop or distribute cryptographic code.


Copyright (c) 1998-2021 The OpenSSL Project

Copyright (c) 1995-1998 Eric A. Young, Tim J. Hudson

All rights reserved.