A local copy of OpenSSL from GitHub
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Pauli 31656f2785 Add invalid input length error 3 months ago
.github CI: remove spurious blank lines 4 months ago
Configurations Add multilib to the NonStop configuration definitions. 3 months ago
VMS VMS documentation fixes 10 months ago
apps CMS app: Fix new -wrap option 3 months ago
crypto Add invalid input length error 3 months ago
demos Add config_diagnostics to our configuration files. 4 months ago
dev Ensure ordinals are created during release process 5 months ago
doc Fix documentation referring to 'function code' 4 months ago
engines afalg: add some memory initialisation calls to pacify memory sanitisation. 5 months ago
external/perl Update the bundled external perl module Text-Template to version 1.56 2 years ago
fuzz Fix the error handling in i2v_AUTHORITY_KEYID 3 months ago
gost-engine@62583fb222 Updated gost-engine to latest commit from master branch 7 months ago
include Add invalid input length error 3 months ago
krb5@aa9b4a2a64 Update dependencies for krb5 external test 5 months ago
ms Update copyright year 8 months ago
os-dep Move Haiku configuration to separate config file to denote 6 years ago
providers Add invalid input length error 3 months ago
pyca-cryptography@0034926f2c update pyca-cryptography regression test suite 5 months ago
ssl Fix the array size of dtlsseq in tls1_enc 3 months ago
test test: add unit tests for TDES key wrap 3 months ago
tools Move some OpenSSL perl utility functions to OpenSSL::Util 7 months ago
util Replace CONFIG_NOWAIT env var with -w option 4 months ago
wycheproof@2196000605 add wycheproof submodule 7 months ago
.gitattributes Remove the external BoringSSL test 8 months ago
.gitignore Add wrap.pl to .gitignore 5 months ago
.gitmodules add wycheproof submodule 7 months ago
ACKNOWLEDGEMENTS.md Fix issues reported by markdownlint 2 years ago
AUTHORS.md Add some missing committers to the AUTHORS list 10 months ago
CHANGES.md changes: add note about 3DES key wrap matching the standard 3 months ago
CONTRIBUTING.md Drop Travis 10 months ago
Configure Replace CONFIG_NOWAIT env var with -w option 4 months 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 1 year ago
INSTALL.md Replace CONFIG_NOWAIT env var with -w option 4 months ago
LICENSE.txt Rename NOTES*, README*, VERSION, HACKING, LICENSE to .md or .txt 1 year ago
NEWS.md news/changes: fix formatting nits 3 months ago
NOTES-ANDROID.md Unify the markdown links to the NOTES and README files 10 months ago
NOTES-DJGPP.md Unify the markdown links to the NOTES and README files 10 months ago
NOTES-NONSTOP.md Add multilib to the NonStop configuration definitions. 3 months ago
NOTES-PERL.md Fix issues found by md-nits 6 months ago
NOTES-UNIX.md Add a clarification to NOTES-UNIX.md 3 months ago
NOTES-VALGRIND.md Unify the markdown links to the NOTES and README files 10 months ago
NOTES-VMS.md Fix issues found by md-nits 6 months ago
NOTES-WINDOWS.md Fix issues found by md-nits 6 months ago
README-ENGINES.md README-ENGINES: fix the link to the provider API README 10 months ago
README-FIPS.md Add migration guide for 3.0 7 months ago
README-PROVIDERS.md Fix issues found by md-nits 6 months ago
README.md Unify the markdown links to the NOTES and README files 10 months ago
SUPPORT.md Fix SUPPORT.md for better readability 1 year ago
VERSION.dat Prepare for 3.0 beta 3 4 months ago
appveyor.yml Simplify AppVeyor configuration 7 months ago
build.info Building: Add necessary dependencies for linker scripts and .rc files 6 months ago
config config: Turn into a simple wrapper 1 year ago
config.com Update copyright year 1 year ago
configdata.pm.in configdata.pm: Allow extra arguments when --query is given. 6 months ago
e_os.h Remove I_CAN_LIVE_WITH_LNK4049 6 months ago


Welcome to the OpenSSL Project

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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.