Off-the-Record (OTR) Messaging allows you to have private conversations
over instant messaging by providing:
- No one else can read your instant messages.
- You are assured the correspondent is who you think it is.
- The messages you send do not have digital signatures that are
checkable by a third party. Anyone can forge messages after a
conversation to make them look like they came from you. However,
during a conversation, your correspondent is assured the messages
he sees are authentic and unmodified.
- Perfect forward secrecy
- If you lose control of your private keys, no previous conversation is compromised.
21 Oct 2014
- pidgin-otr 4.0.1 released
- This point-release includes the following updates:
- Fix max message size for Novell Groupwise
- New Czech, Finnish, Brazilian Portuguese, Norwegian Bokmål
translations. Updated French, Chinese
- The Windows binary has been linked with updated
versions of libotr, libgcrypt, and libgpg-error.
- libotr 4.1.0 released
- This minor-version update includes the following changes:
- Modernized autoconf build system
- Use constant-time comparisons where needed
- Use gcrypt secure memory allocation
- Correctly reject attempts to fragment a message into too many
- Fix a missing opdata when sending message fragments
- Don't lose the first user message when REQUIRE_ENCRYPTION is
- Fix some memory leaks
- Correctly check for children contexts' state when forgetting
- API Changes:
- Added API functions otrl_context_find_recent_instance
10 Oct 2014
- git repos and bugtracker now on otr.im
- We now link to the new git repositories and the bugtracker
on the community development site, otr.im.
28 Sept 2013
- Now running on a new server
- We've migrated the OTR website to a new and faster server.
(Updated 3 Oct 2013): The URL is now https://otr.cypherpunks.ca/,
as we have enabled TLS.
24 July 2013
- Now experimenting with Bitcoin for donations
- If you'd like to donate to the OTR project using Bitcoin,
bitcoin:14Tyk13ELKcRaJe1CfZE8f58QcBHfeV1tQ?label=OTR is ready to receive your support.
OTR library and toolkit
This is the portable OTR Messaging Library, as well as the toolkit to
help you forge messages. You need this library in order to use the other
OTR software on this page. [Note that some binary packages, particularly
Windows, do not have a separate library package, but just include the library
and toolkit in the packages below.] The current version is 4.1.0.
UPGRADING from version 3.2.x
- Source code (4.1.0)
- Compressed tarball
Java OTR library
This is the Java version of the OTR library. This is for developers of Java applications that want to add support for OTR. End users do not require this package. It's still early days, but you can download java-otr version 0.1.0 (sig).
OTR localhost AIM proxy
This software is no longer supported. Please use an IM client with native support for OTR.
This is a localhost proxy you can use with almost any AIM client in order
to participate in Off-the-Record conversations. The current version is
0.3.1, which means it's still a long way from done. Read the README
file carefully. Some things it's still missing:
- Username/password authentication to the proxy
- Having the proxy be able to use outgoing proxies itself
- Support for protocols other than AIM/ICQ
- Configurability of the proxy types and ports it uses
But it should work for most people. Please send feedback to the
otr-users mailing list
, or to the dev team
You may need the above library packages.
- Source code (0.3.1)
- Compressed tarball
- Windows (0.3.1)
- Win32 installer
- OS X (0.3.1)
- OS X package
If you use OTR software, you should join at least the otr-announce
mailing list, and possibly otr-users
(for users of OTR software) or otr-dev (for developers of OTR software) as well.
- What implementations of Off-the-Record Messaging are there?
- Please see our OTR-enabled software page.
The OTR functionality is separated into the
Off-the-Record Messaging Library (libotr), which is an LGPL-licensed
library that can be used to (hopefully) easily produce OTR plugins for
other IM software, or for other applications entirely.
- What is the license for the OTR software?
- The Off-the-Record Messaging Library is licensed under version 2.1
of the GNU Lesser General
Public License. The Off-the-Record Toolkit, the pidgin-otr plugin,
and the OTR proxy are licensed under version 2 of the GNU General Public
- How is this different from the pidgin-encryption plugin?
- The pidgin-encryption plugin provides encryption and authentication,
but not deniability or perfect forward secrecy. If an attacker or a
virus gets access to your machine, all of your past
pidgin-encryption conversations are retroactively compromised. Further,
since all of the messages are digitally signed, there is
difficult-to-deny proof that you said what you did: not what we want
for a supposedly private conversation!
- How is this different from Trillian's SecureIM?
- SecureIM doesn't provide any kind of authentication at all! You
really have no idea (in any kind of secure way) to whom you're speaking,
or if there is a "man in the middle" reading all of your messages.
- How is this different from SILC?
- SILC uses a completely separate network of servers and underlying
network protocol. In some environments, such as firewalled or corporate
setups, where a local proprietary IM protocol may be in use, SILC may
not be available. Further, in its normal mode of operation, all SILC messages
are shared with the SILC servers; if you want to send messages that can only
be read by the person with whom you're communicating, you need to either
(1) arrange a pre-shared secret in advance (which hampers perfect forward
secrecy), or (2) be able to do a direct peer-to-peer connection to the other
person's client, in order to do a key agreement (which may not be possible in
a NAT or firewall situation).
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