Security researchers have a working prototype of an instant messaging application that aims to thoroughly obscure and scrub evidence that two parties have been chatting.
The Invisible.im project, which is looking for developers, aims to solve a difficult security problem of online messaging services: metadata, or information about other data that can give law enforcement and governments leads on people they're investigating.
Even if an IM conversation between two people is encrypted, a determination that two people merely communicated can be enough for authorities to ask a court for warrants for other information that could eventually compromise their conversations.
That information could come from buddy lists or instant messaging servers that broker conversations and log information.
"Invisible.im makes it possible for any member of the public to communicate with a journalist (or indeed, anyone) without leaving a retrospectively recoverable forensic trail behind on third-party servers," according to the project's website.
Invisible.im was launched by IT security analyst Patrick Gray; HD Moore, chief research officer of the security company Rapid7; the vulnerability researcher known as "The Grugq" and another researcher, Ducktor Richö.
The foundation of Invisible.im is built around XMPP, the widely used chat protocol. But rather than using servers across the Internet to broker the transfer of messages, Invisible.im sets up a local XMPP server on a user's computer.
That local XMPP server then connects to a TOR hidden service. TOR is short for The Onion Router, an anonymity network that encrypts Internet traffic in order to give greater privacy to a Web browser. TOR can also be used to set up a "hidden" website, or one hosted on the network whose true IP address is masked.
Chats are encrypted using OTR, or Off The Record, an encryption plugin. Invisible.im will use "ephemeral" encryption keys for those OTR sessions, which are scrubbed when the chat session ends. Chats will also have another layer of encryption by virtue of using TOR.
An "anonymous" mode of Invisible.im will allow a person to contact another person, for example, by downloading Invisible.im and then entering the hidden service address of the person. The project is considering creating an address book so people can find the verifiable addresses of others they wish to contact.
A more secure mode will allow two people who have been cryptographically verified to chat. In that mode, "no one can tell they are on each other's 'buddy lists' or that they have ever had a conversation, let alone when," according to the project's website.
It means authorities will not be able to infer relationships between users of the program by passively observing internet traffic, it said.
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