Technical Details on BitTorrent Secure P2P Chat

BitTorrent has provided technical details on the implementation of the BitTorrent Chat cryptographically protected P2P service, which is now in closed alpha testing . Its main advantage is the absence of a central server, so that messages are transmitted directly from the sender's device to the subscriber's device without intermediaries.

Only the search for a destination is carried out through the DHT network. For comparison, in traditional IM services, both the search for the recipient and the content of the message are transmitted through a central server.


')
The public request for creating a cryptographically secure, reliable chat is stronger than ever. Various commercial companies are trying to implement it, and we should not forget that BitTorrent is also a commercial American company. Nevertheless, they set a goal to create a reliable technology that can become the standard for secure communications. “In the end, we realized that we have a unique experience in creating such a platform,” the company writes in the official blog.

BitTorrent Chat will use asymmetric cryptography to protect the privacy of the user. In this case, the concept of "user name" is not used at all, the system does not have an authorization procedure in the classical sense, with a user name and password. Instead, each user generates a unique pair of private and public keys. For all users of the BitTorrent Chat network, you are your public key . In other words, you can use chat completely anonymously. Two users only need to exchange public keys to establish a secure communication channel.

The use of asymmetric cryptography in P2P chat gives several advantages. The main thing - a reliable and convenient way to encrypt messages using the private key. The problem is that if someone extracts your private key, it can decrypt the archive of old (and future) messages. Fortunately, BitTorrent has implemented a forward secrecy system. At the beginning of each conversation, a temporary cryptographic key is generated. It is created on the basis of your secret and public key, and after the conversation is deleted forever.

The key technology behind BitTorrent Chat is the DHT (distributed hash table) - a distributed hash table for translating users' public keys into IP addresses. Here it works the same as in popular torrent clients like µTorrent. Recent versions of DHT support encryption to protect sensitive information that is transmitted to the network. Read more about DHT here .