TORFone - voice add-on for TorChat
The fundamental right to privacy, guaranteed by the Fifth and Fourteenth Amendments to the U. S. Constitution, protects against unwarranted invasions of privacy by federal or state entities, or arms thereof.
Internet telephony is now an important part of people communications and should be protected from intruders, collecting information about you. I had an idea to use the old PGPFone designed by Philip Zimmermann for these purposes by adding the possibility to use The Onion Router anonymizer to ensure anonymity of callers. I did some tests to adopt VoIP transport to TOR tunnels and eventually made acceptable alpha release. Now the beta version is available which includes an improved cryptography, new voice codecs and lot of other new features.
As a result, the TORFone was designed to communicate voice via Internet (make phone calls to the addressee) similarly to Skype but with the following differences:
1. TORFone is an open source project, therefore it indicates no "backdoors" and allows quick fixing of potential vulnerabilities.
2. TORFone is fully portable (it can be run from a flash carrier or virtual TrueCrypt-disk and leaves no residue in the system) and works with all versions of Win32 from Windows 98, has very low system requirements (above PI 233 MHz 32M RAM). It saves bandwidth (required from only 2 kbit/s each side using low-bitrates codecs).
3. TORFone is decentralized, i.e. it does not use an external server and does not require pre-registration number.
4. TORFone provides full confidentiality (by using DH-4096 to match the session key, AES-256-OCB to encrypt the voice traffic and PKDF2+HMAC for autentification). The attacker who mirrors the traffic is unable to listen to the conversation and is not able to decode it later even if he gains access to the computers of participants.
5. Caller and callee are completely anonymous to each other and to outside observers (a call is made on Tor hidden service user).
6. Calls using TORFone are hidden to the outside observer because the TORFone can use the Tor network as a transport layer. Since Tor can simulate usual HTTPS-connections using Tor bridges, the same level of indistinguishability may be provied also for TORFone traffic. If TORFone is used without anonymity by making direct connection thorugh Internet, it still may be resistant against some type of DPI because TORFone uses its own protocol (not RTP/ZRTP), which can work over both TCP and UDP connection.
I think now that TORFone is one of the most anonymous and confidential tools for the Internet telephony. The payment for anonymity is voice latency up to 2-4 seconds (because traffic goes through a chain of few nodes located around the world). If anonymity is not required TORFone can work as a direct connection "point to point" using IP-adress / domain name which fully keeps the privacy. Can be used a direct TCP or UDP connection. Furthermore, first Tor may be used as SIP-server to connect to the hidden service of subscriber, and then for NAT traversal and installation secure UDP direct connection. TORFone also provides subscriber voice authentication to avoid attack "man in the middle" and authenticated using a preset phrases with the silent notification under pressure. Also TORFone can be used to exchange by personal data (such as files or short text messaging) safely.