OpenSSL 0.9.8zh 3 Dec 2015
Copyright (c) 1998-2011 The OpenSSL Project
Copyright (c) 1995-1998 Eric A. Young, Tim J. Hudson
All rights reserved.
The OpenSSL Project is a collaborative effort to develop a robust,
commercial-grade, fully featured, and Open Source toolkit implementing the
Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1)
protocols as well as a full-strength general purpose cryptography library.
The project is managed by a worldwide community of volunteers that use the
Internet to communicate, plan, and develop the OpenSSL toolkit and its
OpenSSL is based on the excellent SSLeay library developed from Eric A. Young
and Tim J. Hudson. The OpenSSL toolkit is licensed under a dual-license (the
OpenSSL license plus the SSLeay license) situation, which basically means
that you are free to get and use it for commercial and non-commercial
purposes as long as you fulfill the conditions of both licenses.
The OpenSSL toolkit includes:
Implementation of SSLv2, SSLv3, TLSv1 and the required code to support
both SSLv2, SSLv3 and TLSv1 in the one server and client.
General encryption and X.509 v1/v3 stuff needed by SSL/TLS but not
actually logically part of it. It includes routines for the following:
libdes - EAY's libdes DES encryption package which was floating
around the net for a few years, and was then relicensed by
him as part of SSLeay. It includes 15 'modes/variations'
of DES (1, 2 and 3 key versions of ecb, cbc, cfb and ofb;
pcbc and a more general form of cfb and ofb) including desx
in cbc mode, a fast crypt(3), and routines to read
passwords from the keyboard.
RC2 encryption - 4 different modes, ecb, cbc, cfb and ofb.
Blowfish encryption - 4 different modes, ecb, cbc, cfb and ofb.
IDEA encryption - 4 different modes, ecb, cbc, cfb and ofb.
MD5 and MD2 message digest algorithms, fast implementations,
SHA (SHA-0) and SHA-1 message digest algorithms,
MDC2 message digest. A DES based hash that is popular on smart cards.
There is no limit on the number of bits.
There is no limit on the number of bits.
Diffie-Hellman key-exchange/key generation.
There is no limit on the number of bits.
X509 encoding/decoding into/from binary ASN1 and a PEM
based ASCII-binary encoding which supports encryption with a
private key. Program to generate RSA and DSA certificate
requests and to generate RSA and DSA certificates.
The normal digital envelope routines and base64 encoding. Higher
level access to ciphers and digests by name. New ciphers can be
loaded at run time. The BIO io system which is a simple non-blocking
IO abstraction. Current methods supported are file descriptors,
sockets, socket accept, socket connect, memory buffer, buffering, SSL
client/server, file pointer, encryption, digest, non-blocking testing
A dynamically growing hashing system
A simple stack.
A Configuration loader that uses a format similar to MS .ini files.
A command line tool that can be used for:
Creation of RSA, DH and DSA key parameters
Creation of X.509 certificates, CSRs and CRLs
Calculation of Message Digests
Encryption and Decryption with Ciphers
SSL/TLS Client and Server Tests
Handling of S/MIME signed or encrypted mail
Various companies hold various patents for various algorithms in various
locations around the world. _YOU_ are responsible for ensuring that your use
of any algorithms is legal by checking if there are any patents in your
country. The file contains some of the patents that we know about or are
rumored to exist. This is not a definitive list.
RSA Security holds software patents on the RC5 algorithm. If you
intend to use this cipher, you must contact RSA Security for
licensing conditions. Their web page is http://www.rsasecurity.com/.
RC4 is a trademark of RSA Security, so use of this label should perhaps
only be used with RSA Security's permission.
The IDEA algorithm is patented by Ascom in Austria, France, Germany, Italy,
Japan, the Netherlands, Spain, Sweden, Switzerland, UK and the USA. They
should be contacted if that algorithm is to be used; their web page is
NTT and Mitsubishi have patents and pending patents on the Camellia
algorithm, but allow use at no charge without requiring an explicit
licensing agreement: http://info.isl.ntt.co.jp/crypt/eng/info/chiteki.html
To install this package under a Unix derivative, read the INSTALL file. For
a Win32 platform, read the INSTALL.W32 file. For OpenVMS systems, read
Read the documentation in the doc/ directory. It is quite rough, but it
lists the functions; you will probably have to look at the code to work out
how to use them. Look at the example programs.
For some platforms, there are some known problems that may affect the user
or application author. We try to collect those in doc/PROBLEMS, with current
thoughts on how they should be solved in a future of OpenSSL.
See the OpenSSL website www.openssl.org for details of how to obtain
commercial technical support.
If you have any problems with OpenSSL then please take the following steps
- Download the current snapshot from ftp://ftp.openssl.org/snapshot/
to see if the problem has already been addressed
- Remove ASM versions of libraries
- Remove compiler optimisation flags
If you wish to report a bug then please include the following information in
any bug report:
- On Unix systems:
Self-test report generated by 'make report'
- On other systems:
OpenSSL version: output of 'openssl version -a'
OS Name, Version, Hardware platform
Compiler Details (name, version)
- Application Details (name, version)
- Problem Description (steps that will reproduce the problem, if known)
- Stack Traceback (if the application dumps core)
Report the bug to the OpenSSL project via the Request Tracker
(http://www.openssl.org/support/rt.html) by mail to:
In order to avoid spam, this is a moderated mailing list, and it might
take a day for the ticket to show up. (We also scan posts to make sure
that security disclosures aren't publically posted by mistake.) Mail to
this address is recorded in the public RT (request tracker) database (see
https://www.openssl.org/support/rt.html for details) and also forwarded
the public openssl-dev mailing list. Confidential mail may be sent to
email@example.com (PGP key available from the key servers).
Please do NOT use this for general assistance or support queries.
Just because something doesn't work the way you expect does not mean it
is necessarily a bug in OpenSSL.
You can also make GitHub pull requests. If you do this, please also send
mail to firstname.lastname@example.org with a link to the PR so that we can more easily
keep track of it.
HOW TO CONTRIBUTE TO OpenSSL
Development is coordinated on the openssl-dev mailing list (see
http://www.openssl.org for information on subscribing). If you
would like to submit a patch, send it to email@example.com with
the string "[PATCH]" in the subject. Please be sure to include a
textual explanation of what your patch does.
If you are unsure as to whether a feature will be useful for the general
OpenSSL community please discuss it on the openssl-dev mailing list first.
Someone may be already working on the same thing or there may be a good
reason as to why that feature isn't implemented.
Patches should be as up to date as possible, preferably relative to the
current Git or the last snapshot. They should follow our coding style
(see http://openssl.org/about/codingstyle.txt) and compile without
warnings using the --strict-warnings flag. OpenSSL compiles on many
varied platforms: try to ensure you only use portable features.
Note: For legal reasons, contributions from the US can be accepted only
if a TSU notification and a copy of the patch are sent to firstname.lastname@example.org
(formerly BXA) with a copy to the ENC Encryption Request Coordinator;
please take some time to look at
http://w3.access.gpo.gov/bis/ear/pdf/740.pdf (EAR Section 740.13(e))
for the details. If "your encryption source code is too large to serve as
an email attachment", they are glad to receive it by fax instead; hope you
have a cheap long-distance plan.
Our preferred format for changes is "diff -u" output. You might
generate it like this:
# cd openssl-work
# [your changes]
# ./Configure dist; make clean
# cd ..
# diff -ur openssl-orig openssl-work > mydiffs.patch