A local copy of OpenSSL from GitHub
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Tomas Mraz 2c181ac5a6 sm2: Cleanup handling of DIGEST and DIGEST_SIZE parameters 1 year ago
.github Explicitly enable or disable fips if it is or is not relevant for the test 1 year ago
Configurations build.info: add the Perl wrapper to build generator programs on Windows 1 year ago
VMS VMS documentation fixes 2 years ago
apps Fix memory leak in load_key_certs_crls() when using stdin. 1 year ago
crypto CORE: Rework the pre-population of the namemap 1 year ago
demos Update copyright year 1 year ago
dev Update copyright year 2 years ago
doc Update OSSL_STORE_attach() documentation to indicate it increases the ref_count of the passed in bio 1 year ago
engines engine: fix double free on error path. 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 library context and property query support into the PKCS12 API 1 year ago
krb5@3195e18f66 Update krb5 module to latest release 1 year ago
ms Update copyright year 1 year ago
os-dep Move Haiku configuration to separate config file to denote 6 years ago
providers sm2: Cleanup handling of DIGEST and DIGEST_SIZE parameters 1 year ago
pyca-cryptography@62124e673a updated pyca/cryptography submodule version 1 year ago
ssl Defer Finished MAC handling until after state transition 1 year ago
test acvp: fix the no-acvp_test build 1 year ago
tools Update copyright year 1 year ago
util Add library context and property query support into the PKCS12 API 1 year ago
wycheproof@2196000605 add wycheproof submodule 1 year ago
.gitattributes Remove the external BoringSSL test 1 year ago
.gitignore Resurrect and modernize C++Builder config 1 year ago
.gitmodules add wycheproof submodule 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 2 years ago
CHANGES.md Document the API breaking constification changes 1 year ago
CONTRIBUTING.md Drop Travis 2 years ago
Configure acvp: fix the no-acvp_test build 1 year ago
FAQ.md doc: introduce some minimalistic markdown without essential changes 3 years ago
HACKING.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2 years ago
INSTALL.md acvp: fix the no-acvp_test build 1 year ago
LICENSE.txt Rename NOTES*, README*, VERSION, HACKING, LICENSE to .md or .txt 2 years ago
NEWS.md Prepare for 3.0 alpha 16 1 year ago
NOTES-ANDROID.md Unify the markdown links to the NOTES and README files 2 years ago
NOTES-DJGPP.md Unify the markdown links to the NOTES and README files 2 years ago
NOTES-NONSTOP.md Rewrite the HPE NonStop Notes file in Markdown with more explanations. 2 years ago
NOTES-PERL.md Added Perl installation instructions to NOTES-PERL.md for HPE NonStop. 1 year ago
NOTES-UNIX.md Unify the markdown links to the NOTES and README files 2 years ago
NOTES-VALGRIND.md Unify the markdown links to the NOTES and README files 2 years ago
NOTES-VMS.md Reformat some NOTES and README files 2 years 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 2 years ago
README-FIPS.md README-FIPS: document the installation of the FIPS provider 1 year ago
README-PROVIDERS.md Add a skeleton README-PROVIDERS file 2 years ago
README.md Unify the markdown links to the NOTES and README files 2 years ago
SUPPORT.md Fix SUPPORT.md for better readability 2 years ago
VERSION.dat Prepare for 3.0 alpha 16 1 year ago
appveyor.yml appveyor.yml: clarify conditions for building the plain configuration 1 year ago
build.info Build resource files 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 Avoid #include with inline function on C++Builder 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.