TOR BROWSER TECHNOLOGY

This blog is about the software and anonymity network. To know more about this,see The Tor Project, Inc.

 Tor is free software for enabling anonymous communication . Tor aims to conceal its users' identities and their online activity from surveillance and traffic analysis by separating identification and routing. This is done by passing the data through a circuit of at least three different routers. The data that passes through the network is encrypted, but at the beginning and end node, there is no encryption..

The Tor browser protects you by bouncing your communications around a distributed network of relays run by volunteers all around the world: it prevents somebody watching your Internet connection from learning what sites you visit, it prevents the sites you visit from learning your physical location, and it lets you access sites which are blocked.

Tor Browser lets you use Tor on Windows, Mac OS X, or Linux without needing to install any software. It can run off a USB flash drive, comes with a pre-configured web browser to protect your anonymity, and is self-contained.

Before getting into the actual topic first we need to question our Self why do we need Tor browser as we already n number of browsers like Chrome, Firefox, Opera etc., For this question as a blogger i can give you a single word answer that is we need anonymity. So, you may raise a another question why do we need anonymity?.

Why do we need anonymity?

·       To hide user identity from target web site

·       To hide browsing pattern from employer or ISP

·       To conceal our internet usage from hackers

·       To circumvent censorship

·       To hide user personal information

·       Freedom of Thought and Speech

·       Freedom of Social and Political Activities

       

    Fig: Graphical representation of Tor Network.

                                 R1,R2, R3, R4, R5, R6 are different routers through a request is passing from the client to server.
How Tor Works? --- Onion Routing,Integrity Checking,Node to Node Connection

•      A circuit is built incrementally one hop by one hop

•      Onion-like encryption

•      ‘Alice’ negotiates an AES key with each router

•      Messages are divided into equal sized cells

•      Each router knows only its predecessor and successor

•      Only the Exit router (OR3) can see the message, however it does not know where the message is from

  •      Onion routers communicate with one another, and with users’ OPs, via TLS connections with ephemeral keys. Traffic passes along these connections in fixed-size cells

           •      All data is sent in fixed size (bytes) cells

           •      Control cell commands:

     •      Padding, create, destroy

           •      Relay cell commands:

     •      Begin, data, connected, teardown, ...

Node to Node Connection

•      Tor implements Perfect Forward Secrecy (PFC) by using AES encryption

•      In AES (Advanced Encryption Standard), a private key is generated and shared between the two users, and from this key, session keys are generated

•      Original keypairs are only used for signatures (i.e. to verify the authenticity of messages).

Integrity Checking

•      Only done at the edges of a stream.

•      SHA-1 digest of data sent and received.

•      First 4 bytes of digest are sent with each message for verification.

Tor network overview

                                                     Fig: Commands in use for Tor Network.

TOR: Hidden Services

•      Location-hidden services allow a server to offer a TCP service without revealing its IP address.

•      Tor accommodates receiver anonymity by allowing location hidden services

•      Design goals for location hidden services

•      Access Control: filtering incoming requests

•      Robustness: maintain a long-term pseudonymous identity

•      Smear-resistance: against socially disapproved acts

•      Application transparency

•      Allows to access onion websites and deep web.

TOR: Limitations

•      DNS Leakage : the client reveals the destination to the DNS server during DNS resolution.

•      End-to-end timing correlation: An attacker watching patterns of traffic at the initiator and the responder will be able to confirm the correspondence with high probability.

•      Eavesdropping by exit nodes: Tor does not encrypt the traffic between an exit node and the  target server. Therefore a malicious exit node can observe traffic , identify user request and can send the wrong response.

•      Tor is slow: Traffic is bouncing through ORs and even on volunteers' computers in various  parts of the world. This may cause some bottleneck and network latency.

APPLICATIONS OF ANONYMOUS SYSTEMS ( TOR)

•      Privacy and security for Ordinary Internet Users:   it allows people to communicate with each other without necessarily revealing their personal network identification and without  being tracked by others.

•      Censorship resistance:  Tor provide a strong foundation for censorship resistance for people living under oppressive regimes that try to limit what their citizens can say and do on the Internet.

•      Corporate /Business : Corporate or business organizations may want to keep their data and transactions secure and secret from opponents who are regularly monitoring their activities . Anonymous systems can then be used to achieve untracebility.

Licit and illicit uses

•      Tor is increasingly in common use by victims of domestic violence and the social workers and agencies which assist them

•      A growing list of news organizations are using the SecureDrop software platform to accept material for publication in a manner intended to protect the anonymity of sources.

•      It is endorsed by civil liberties groups as a method for whistleblowers and human rights workers to communicate with journalists

•      Tor is used for matters that are, or may be, illegal in some countries, e.g., to gain access to censored information, to organize political activities, or to circumvent laws against criticism of heads of state.

•      Tor can be used for anonymous defamation, unauthorized leaks of sensitive information and copyright infringement, distribution of illegal sexual content, selling controlled substances, money laundering, credit card fraud, and identity theft.

•       Ironically, Tor has been used by criminal enterprises, hacktivism groups, and law enforcement agencies at cross purposes, sometimes simultaneously.

Dangers of using Tor Network

•      "The more you hide the more somebody wants to know why.“

•      While the inter-relay communications might be secure, the entry and exit nodes are vulnerable to packet sniffing and

•      The exit node decrypts the packet it received from its sibling on the chain of nodes and receives your full plaintext request. This can be easily seen by the operator of the exit node.

•      Running an exit node is dangerous as all exit traffic, legal and illegal, will be traced to your IP

•      Anyone using TOR network is on the NSA watch list under the Xkeyscore program.

                                         Fig: TOR usage across the world

CONCLUSION

              Researches in the last 30 years has made significant progress towards enabling private and anonymous communication on the Internet. With an increasing level of public awareness about threats to personal privacy, such as identity theft or online advertisers tracking user behavior, academic and public interest in anonymous communication systems is likely to continue to increase in the near future. As a result public and academic interest in improving existing systems for anonymity is also increasing. This may enable and encourage future global network design to include privacy and anonymity as fundamental property.

References

•      https://www.torproject.org/

•      https://en.wikipedia.org/wiki/Tor_(anonymity_network)

•      McCoy, Damon; Bauer, Kevin; Grunwald, Dirk; Kohno, Tadayoshi; Sicker, Douglas (2008)."Shining Light in Dark Places: Understanding the Tor Network". Proceedings of the 8th International Symposium on Privacy Enhancing Technologies. 8th International Symposium on Privacy Enhancing Technologies. Berlin, Germany: Springer-Verlag. pp. 63–76.

•       "Tor Project Form 990 2008". Tor Project. Tor Project. 2009. Retrieved 30 August 2014.

•      "Tor Project Form 990 2007". Tor Project. Tor Project. 2008. Retrieved 30 August 2014.

•       "Tor Project Form 990 2009". Tor Project. Tor Project. 2010. Retrieved 30 August 2014.

•      Samson, Ted (5 August 2013). "Tor Browser Bundle for Windows users susceptible to info-stealing attack". InfoWorld. 

•      Dingledine, Roger (7 April 2014). "OpenSSL bug CVE-2014-0160". Tor Project. 

•       Le Blond, Stevens; Manils, Pere; Chaabane, Abdelberi; Ali Kaafar, Mohamed; Castelluccia, Claude; Legout, Arnaud; Dabbous, Walid (March 2011). "One Bad Apple Spoils the Bunch: Exploiting P2P Applications to Trace and Profile Tor Users". 4th USENIX Workshop on Large-Scale Exploits and Emergent Threats (LEET '11). National Institute for Research in Computer Science and Control.