<http://www.cypherpunks.ca/otr/>
Off-the-Record Messaging News - Downloads - Mailing Lists - Documentation - Frequently Asked Questions - Press Off-the-Record (OTR) Messaging allows you to have private conversations over instant messaging by providing: Encryption No one else can read your instant messages. Authentication You are assured the correspondent is who you think it is. Deniability 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. News 24 Feb 2005 otrproxy-0.2.0 released. Changes from 0.1.x: * There's now a GUI! See the README for more details. 23 Feb 2005 gaim-otr 2.0.1 released. Changes from 2.0.0: * Removed people without fingerprints from the Known Fingerprints list. * The column heads in the Known Fingerprints list cause sorting to happen in the expected way. 22 Feb 2005 Nikita made a 0.1.2 version of otrproxy for OSX. Changes from 0.1.1: * AIM screen names should be compared case- and space- insensitively. 16 Feb 2005 Version 2.0.1 of libotr released. Changes from 2.0.0: * Don't send encrypted messages to a buddy who has disconnected his private connection with us. * Don't show the user the "the last message was resent" notice if the message has never actually been sent before. * Fix a crash bug that happened when messages were retransmitted under certain circumstances. More News... Downloads 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 2.0.1. README Source code (2.0.1) Compressed tarball (sig) Fedora Core 3 SRPM [Note that if you're compiling from source on win32, you may need to make this patch to libgcrypt-1.2.1.] Linux/x86 (2.0.1) Debian testing/unstable Debian testing/unstable dev package Fedora Core 3 RPM Fedora Core 3 dev RPM Linux/x86_64 (2.0.1) Fedora Core 3 RPM Fedora Core 3 dev RPM OTR plugin for gaim This is a plugin for gaim 1.x which implements Off-the-Record Messaging over any IM network gaim supports. The current version is 2.0.1. You may need the above library packages. README Source code (2.0.1) Compressed tarball (sig) Fedora Core 3 SRPM Linux/x86 (2.0.1) Debian testing/unstable (Debian stable does not have the required 1.x version of gaim) Fedora Core 3 RPM Linux/x86_64 (2.0.1) Fedora Core 3 RPM Windows (2.0.1) Win32 installer (sig) OTR localhost AIM proxy 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 0.2.0, 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. README Source code (0.2.0) Compressed tarball (sig) Fedora Core 3 SRPM Linux/x86 (0.2.0) Debian testing/unstable Fedora Core 3 RPM Windows (0.2.0) Win32 installer (sig) OSX (0.2.0) OSX package Mailing Lists 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. Documentation Here are some documents and papers describing OTR. The WPES presentation is quite useful to get started. * Protocol description * The WPES 2004 version of our paper * Our WPES presentation (Powerpoint) * Our WPES presentation (PDF) Frequently Asked Questions What implementations of Off-the-Record Messaging are there? Right now, there's the plugin for gaim, which is supported on Linux and Windows. There's also the OTR proxy, which is supported on Linux, Windows, and OSX. 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 gaim-otr plugin, and the OTR proxy are licensed under version 2 of the GNU General Public License. How is this different from the gaim-encryption plugin? The gaim-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 gaim-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). Is your question not here? Ask on the otr-users mailing list! Nikita Borisov, Ian Goldberg -- ----------------- R. A. Hettinga <mailto: [EMAIL PROTECTED]> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire' --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]