BitTorrent, Inc.

BitTorrent, Inc. is developing a serverless instant messaging system that relies on public key encryption to protect the privacy of communications, identifying users not with traditional usernames but with cryptographic key pairs.
The company, which develops the BitTorrent peer-to-peer protocol as well as the BitTorrent and μTorrent file sharing software, announced the forthcoming chat software in September and revealed some details on how it will work in a blog post today. It reads:

With BitTorrent Chat, there aren’t any “usernames” per se. You don’t login in the classic sense. Instead, your identity is a cryptographic key pair. To everyone on the BitTorrent Chat network at large, you ARE your public key.

This means that, if you want, you can use Chat without telling anyone who you are. Two users only need to exchange each other’s public keys to be able to chat.
Using public key encryption provides us with a number of benefits.

The most obvious is the ability to encrypt messages to your sender using your private key and their public key. But in public key encryption, if someone gains access to your private key, all of your past (and future) messages could be decrypted and read. In Chat, we are implementing forward secrecy. Every time you begin a conversation with one of your contacts, a temporary encryption key will be generated. Using each of your keypairs, this key will be generated for this one conversation and that conversation only, and then deleted forever.

Underlying this system is a Distributed Hash Table (DHT) which finds IP addresses, removing the need for a central server to route messages, the company explained.

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