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.
Paul Yang e9aa4a16a6 refactor get params functions 2 years ago
.github Fix typos and repeated words 2 years ago
Configurations Configurations/unix-Makefile.tmpl: Don't specify headers twice 2 years ago
VMS Following the license change, modify the boilerplates in last few 4 years ago
apps apps/ocsp: Return non zero exit code with invalid certID 2 years ago
boringssl@2070f8ad91 Update ossl_config.json for later BoringSSL commit 5 years ago
crypto Address review comments 2 years ago
demos Update copyright year 2 years ago
dev dev/release.sh: Rework to be smoother 2 years ago
doc Add const to 'ppin' function parameter 2 years ago
engines Fix typo in bind_loader_attic comment 2 years ago
external/perl Update the bundled external perl module Text-Template to version 1.56 3 years ago
fuzz Fix safestack issues in cmp.h 2 years ago
gost-engine@b008f2a0ff Update gost-engine to fix API rename 2 years ago
include Add SM2 signature algorithm to default provider 2 years 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 refactor get params functions 2 years ago
pyca-cryptography@09403100de Update the pyca-cryptography submodule 4 years ago
ssl Support keys with RSA_METHOD_FLAG_NO_CHECK with OCSP sign 2 years ago
test Add SM2 signature algorithm to default provider 2 years ago
tools Following the license change, modify the boilerplates in util/, tools/ 4 years ago
util Fix merge error with libcrypto.num 2 years ago
.gitattributes Developer scripts: Release script 2 years ago
.gitignore Teach EdDSA signature algorithms about AlgorithmIdentifiers 2 years ago
.gitmodules GOST external tests 2 years 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
.travis.yml Travis: default to HARNESS_JOBS=4 2 years ago
ACKNOWLEDGEMENTS.md Fix issues reported by markdownlint 2 years ago
AUTHORS.md Fix issues reported by markdownlint 2 years ago
CHANGES.md Add a CHANGES entry for the safestack updates 2 years ago
CONTRIBUTING.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
Configure Add 'fips-securitychecks' option and plumb this into the actual fips checks 2 years 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 Add option to fipsinstall to disable fips security checks at run time. 2 years ago
LICENSE.txt Rename NOTES*, README*, VERSION, HACKING, LICENSE to .md or .txt 2 years ago
NOTES-Android.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
NOTES-DJGPP.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
NOTES-Perl.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
NOTES-Unix.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
NOTES-VMS.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
NOTES-Valgrind.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
NOTES-Windows.txt Fix markdown nits in NOTES-Windows.txt 2 years ago
NOTES.HPNS NonStop port updates for 3.0.0. 2 years ago
README-Engine.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
README-FIPS.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
README.md README.md: remove incorrect link to openssl.github.io 2 years ago
SUPPORT.md Fix issues reported by markdownlint 2 years ago
VERSION.dat Prepare for 3.0 alpha 7 2 years ago
appveyor.yml Prevent extended tests run unexpectedly in appveyor 2 years ago
build.info Update err.h to use the new lhash generation code 2 years 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: Don't try to quotify undefined values 3 years ago
e_os.h NonStop port updates for 3.0.0. 2 years ago


Welcome to the OpenSSL Project

openssl logo

travis 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 wiki.


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) 1998-2020 The OpenSSL Project

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

All rights reserved.