A local copy of OpenSSL from GitHub
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Richard Levitte d8c1cafbbc VMS documentation fixes 9 months ago
.github CI: add a non-caching CI loop 8 months ago
Configurations VMS documentation fixes 8 months ago
VMS VMS documentation fixes 8 months ago
apps Deprecate the libssl level SRP APIs 8 months ago
boringssl@2070f8ad91 Update ossl_config.json for later BoringSSL commit 5 years ago
crypto Use ERR_R_*_LIB instead of ERR_LIB_* as reason code for sub-libraries 8 months ago
demos Update copyright year 1 year ago
dev dev/release.sh: Fix typo 9 months ago
doc DOCS: Update the internal documentation on EVP_PKEY. 8 months ago
engines ERR: Rebuild all generated error headers and source files 9 months ago
external/perl Update the bundled external perl module Text-Template to version 1.56 2 years ago
fuzz Add OID for draft-ietf-opsawg-finding-geofeeds detached CMS signature 8 months ago
gost-engine@b008f2a0ff Update gost-engine to fix API rename 1 year ago
include Deprecate the libssl level SRP APIs 8 months ago
krb5@890ca2f401 Update the krb5 submodule 2 years ago
ms Unify all assembler file generators 2 years ago
os-dep Move Haiku configuration to separate config file to denote 6 years ago
providers Use ERR_R_*_LIB instead of ERR_LIB_* as reason code for sub-libraries 8 months ago
pyca-cryptography@09403100de Update the pyca-cryptography submodule 3 years ago
ssl Use ERR_R_*_LIB instead of ERR_LIB_* as reason code for sub-libraries 8 months ago
test Deprecate the libssl level SRP APIs 8 months ago
tools Following the license change, modify the boilerplates in util/, tools/ 3 years ago
util Deprecate the libssl level SRP APIs 8 months ago
.gitattributes TEST: Make our test data binary 11 months ago
.gitignore Fix some missed usage of DEFINE_LHASH_OF() 12 months ago
.gitmodules GOST external tests 1 year ago
.travis-apt-pin.preferences Fix travis clang-3.9 builds 4 years ago
.travis-create-release.sh Remove all 'make dist' artifacts 3 years ago
ACKNOWLEDGEMENTS.md Fix issues reported by markdownlint 1 year ago
AUTHORS.md Add some missing committers to the AUTHORS list 9 months ago
CHANGES.md Update documentation following deprecation of SRP 8 months ago
CONTRIBUTING.md Drop Travis 9 months ago
Configure Deprecate the low level SRP APIs 8 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 VMS documentation fixes 8 months ago
LICENSE.txt Rename NOTES*, README*, VERSION, HACKING, LICENSE to .md or .txt 1 year ago
NEWS.md Prepare for 3.0 alpha 12 9 months ago
NOTES-Android.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 1 year ago
NOTES-DJGPP.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 1 year ago
NOTES-NONSTOP.md Rewrite the HPE NonStop Notes file in Markdown with more explanations. 12 months ago
NOTES-Perl.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 1 year ago
NOTES-Unix.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 1 year ago
NOTES-VMS.md VMS documentation fixes 8 months ago
NOTES-Valgrind.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 1 year ago
NOTES-Windows.txt Fix markdown nits in NOTES-Windows.txt 1 year ago
README-Engine.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 1 year ago
README-FIPS.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 1 year ago
README.md Update copyright year 9 months ago
SUPPORT.md Fix SUPPORT.md for better readability 11 months ago
VERSION.dat Prepare for 3.0 alpha 12 9 months ago
appveyor.yml {.travis,ci,appveyor}.yml: Make minimal config consistent, add no-deprecated no-ec no-ktls no-siv 11 months ago
build.info Configuration: ensure that 'no-tests' works correctly 8 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.in, util/dofile.pl: Make a HERE document stricter. 12 months ago
e_os.h Implement OpenSSL secure memory for Windows 1 year 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.