Alice in onion | Query4All

This thesis examines onion routing: how do different generations differ from each other and what kinds of data security threats onion routing has and what possibilities is there to defend against them and divides these attacks into categories. Cryptographic networks aim to create communication paths through internet that allow sending messages in a way that the origins of the message cannot be linked to its sender. Tor -application uses a technique called onion routing to encrypt messages. The technique gets its name from the data structure inside which information travels from sender to receiver. The machine that initiates the connection forms an onion routing path and wraps the message inside an onion before sending it down the path. An onion is formed from cryptographically encrypted layers that are peeled one by one by each router along the communication path. Tor aims to stay a low latency anonymity service and the technology has been designed with this principle in mind. Different defences like entry guards and bridges offer protection while keeping the computing cost of the network low. First version of onion routing was developed in 1996 and the last, third generation that is still under development was published in 2006. In this thesis we examine onion routing: how do different generations differ from each other and what kinds of data security threats onion routing has and what possibilities is there to defend against them. We discuss eight papers published in the recent years about theoretical attacks, meaning theoretical ways to break the security provided by onion routing technology and divide these attacks into categories. The categories we propose are: Entry and exit onion router selection attacks, Traffic and time analysis based attacks, Autonomous system level and global level attacks, and Software-level attacks.