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Todd Short 25959e04c3 Optimize session cache flushing
Sort SSL_SESSION structures by timeout in the linked list.
Iterate over the linked list for timeout, stopping when no more
session can be flushed.
Do SSL_SESSION_free() outside of SSL_CTX lock
Update timeout upon use

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8687)
2021-06-10 18:32:25 +10:00
.github Add md-nits task 2021-06-04 13:04:18 +10:00
Configurations Add aix64-gcc-as architecture and p2align callback 2021-06-08 18:52:53 +10:00
VMS VMS documentation fixes 2021-02-12 15:57:25 +01:00
apps APPS: Restore the possibility to combine -pubout with -text 2021-06-10 08:34:09 +02:00
crypto Fix use after free in OSSL_HTTP_REQ_CTX_set1_req() 2021-06-10 18:27:15 +10:00
demos Add an EVP demo for signatures using EC 2021-06-03 15:21:17 +10:00
dev Refer to the migration guide rather than the wiki in our announcements 2021-05-20 11:58:29 +01:00
doc Optimize session cache flushing 2021-06-10 18:32:25 +10:00
engines afalg: fix coverity 1485661 improper use of negative value 2021-06-08 19:32:17 +10:00
external/perl Update the bundled external perl module Text-Template to version 1.56 2019-09-12 12:53:32 +02:00
fuzz fuzz: remove TODOs 2021-06-02 16:30:15 +10:00
gost-engine@62583fb222 Updated gost-engine to latest commit from master branch 2021-05-07 15:43:26 +02:00
include Optimize session cache flushing 2021-06-10 18:32:25 +10:00
krb5@3195e18f66 Update krb5 module to latest release 2021-04-19 11:46:39 -07:00
ms Update copyright year 2021-04-22 14:38:44 +01:00
os-dep Move Haiku configuration to separate config file to denote 2016-05-19 22:39:52 +02:00
providers Decoding PKCS#8: separate decoding of encrypted and unencrypted PKCS#8 2021-06-09 17:00:10 +02:00
pyca-cryptography@62124e673a updated pyca/cryptography submodule version 2021-04-27 19:09:03 +10:00
ssl Optimize session cache flushing 2021-06-10 18:32:25 +10:00
test Optimize session cache flushing 2021-06-10 18:32:25 +10:00
tools Move some OpenSSL perl utility functions to OpenSSL::Util 2021-05-19 10:13:02 +02:00
util util: convert SHA* one shots back to being functions 2021-06-10 14:18:06 +10:00
wycheproof@2196000605 add wycheproof submodule 2021-04-27 19:09:03 +10:00
.gitattributes Remove the external BoringSSL test 2021-03-26 14:24:06 +01:00
.gitignore Ignore the threadstest_fips executable 2021-05-26 22:08:10 +10:00
.gitmodules add wycheproof submodule 2021-04-27 19:09:03 +10:00
.travis-apt-pin.preferences Fix travis clang-3.9 builds 2017-06-23 17:57:02 +01:00
.travis-create-release.sh Remove all 'make dist' artifacts 2018-11-23 12:40:32 +01:00
ACKNOWLEDGEMENTS.md Fix issues reported by markdownlint 2020-05-08 16:22:02 +02:00
AUTHORS.md Add some missing committers to the AUTHORS list 2021-02-02 16:45:44 +01:00
CHANGES.md changes: fix woring that mentions SHA* one shot functions are deprecated 2021-06-10 14:18:06 +10:00
CONTRIBUTING.md Drop Travis 2021-01-25 13:41:23 +01:00
Configure Configure: variable expand GENERATE values too 2021-06-02 08:18:47 +02:00
FAQ.md doc: introduce some minimalistic markdown without essential changes 2020-02-26 21:04:38 +01:00
HACKING.md Fix many MarkDown issues in {NOTES*,README*,HACKING,LICENSE}.md files 2020-07-05 11:29:43 +02:00
INSTALL.md Add --banner config option 2021-05-14 08:35:11 +02:00
LICENSE.txt Rename NOTES*, README*, VERSION, HACKING, LICENSE to .md or .txt 2020-07-05 11:29:43 +02:00
NEWS.md Prepare for 3.0 beta 1 2021-05-20 14:30:39 +01:00
NOTES-ANDROID.md Unify the markdown links to the NOTES and README files 2021-02-12 20:41:32 +01:00
NOTES-DJGPP.md Unify the markdown links to the NOTES and README files 2021-02-12 20:41:32 +01:00
NOTES-NONSTOP.md DOC: Slightly improve the documentation of BIO_lookup() and related functions 2021-05-29 07:47:03 +02:00
NOTES-PERL.md Fix issues found by md-nits 2021-05-28 11:14:46 +02:00
NOTES-UNIX.md Unify the markdown links to the NOTES and README files 2021-02-12 20:41:32 +01:00
NOTES-VALGRIND.md Unify the markdown links to the NOTES and README files 2021-02-12 20:41:32 +01:00
NOTES-VMS.md Fix issues found by md-nits 2021-05-28 11:14:46 +02:00
NOTES-WINDOWS.md Fix issues found by md-nits 2021-05-28 11:14:46 +02:00
README-ENGINES.md README-ENGINES: fix the link to the provider API README 2021-02-15 19:33:53 +01:00
README-FIPS.md Add migration guide for 3.0 2021-05-20 08:44:08 +01:00
README-PROVIDERS.md Fix issues found by md-nits 2021-05-28 11:14:46 +02:00
README.md Unify the markdown links to the NOTES and README files 2021-02-12 20:41:32 +01:00
SUPPORT.md Fix SUPPORT.md for better readability 2020-11-14 16:42:41 +01:00
VERSION.dat Prepare for 3.0 beta 1 2021-05-20 14:30:39 +01:00
appveyor.yml Simplify AppVeyor configuration 2021-05-01 13:13:11 +10:00
build.info Build resource files 2021-04-19 11:05:54 +02:00
config config: Turn into a simple wrapper 2020-06-28 18:34:36 +02:00
config.com Update copyright year 2020-07-16 14:47:04 +02:00
configdata.pm.in configdata.pm: Allow extra arguments when --query is given. 2021-05-29 11:02:37 +02:00
e_os.h Remove I_CAN_LIVE_WITH_LNK4049 2021-06-09 18:01:22 +10:00


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.