LILAC: THE SECOND GENERATION LIGHTWEIGHT LOW-LATENCY ANONYMOUS CHAT.

Abstract

Instant messaging is one of the most used modes of communication and there are many instant messaging systems available online. Studies from the Electronic Frontier Foundation show that there are only a few instant messengers that keep your messages safe by providing ,security and limited anonymity. Lilac, a Lightweight Low-latency Anonymous Chat, is a secure instant messenger that provides security as well as better anonymity to users as compared to other messengers. It is a browser-based instant messaging system that uses Tor like a model to protect user anonymity. Compared to existing messengers, LILAC protects the users from traffic analysis by implementing cover traffic. It is built on OTR (Off the Record) messaging to provide forward secrecy and implements Socialist Millionaire Protocol to guarantee the user authenticity. Unlike other existing instant messaging systems, it uses pseudonyms to protect user anonymity. Being a browser-based web application, it does not require any installation and it leaves no footprints to trace. It provides user to save contact details in a secure way, by an option to download the contacts in an encrypted file. This encrypted file can be used to restore the contacts later. In our experimentation with Lilac, we found the Round Trip Time (RTT) for a message is around 3.5 seconds which is great for a messenger that provides security and anonymity. Lilac is readily deployable on different and multiple servers. In this document, we provide in-depth details about the design, development, and results of LILAC.