People trying to communicate across oppressive national firewalls could be interested in ScatterChat, a secure IM (instant messaging) application developed by an international group of hackers, human rights activists, lawyers and security experts.

The application is based on the open-source Gain IM client and uses the anonymous Tor network to offer secure end-to-end encryption for both chat and file transfers, the developer group Hacktivisimo said on Friday.

It's designed for "nontechnical human rights activists and political dissidents" but could also be also useful for corporate environments and other settings where privacy is important, according to the groups' website. The software was launched at the Hope (Hackers On Planet Earth) conference, which ended on Sunday in New York City.

The anonymity and encryption provided by ScatterChat ensures that both the identities and messages of users "remain a mystery", lead developer J Salvatore Testa said in a statement.

ScatterChat, which uses a technique called "onion routing" to hide the computers taking part in a secure conversation, is immune to replay attacks, supports Perfect Forward Secrecy, and features limited message deniability properties, according to its website.

Additional information is available here.