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 has been floating
around the net for a few years. It includes 15
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.
There is no limit on the number of bits.
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 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
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
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
The MDC2 algorithm is patented by IBM.
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.
If you have any problems with OpenSSL then please take the following steps
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
Self-test report generated by 'make report'
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
Note that mail to openssl-bugs@openssl.org is recorded in the publicly
readable request tracker database and is forwarded to a public
mailing list. Confidential mail may be sent to openssl-security@openssl.org
(PGP key available from the key servers).
HOW TO CONTRIBUTE TO OpenSSL
----------------------------
Development is coordinated on the openssl-dev mailing list (see
would like to submit a patch, send it to openssl-dev@openssl.org with
the string "[PATCH]" in the subject. Please be sure to include a
textual explanation of what your patch does.
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 crypt@bis.doc.gov
(formerly BXA) with a copy to the ENC Encryption Request Coordinator;
please take some time to look at
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
# ./Configure dist; make clean