Wednesday, September 13, 2017
Tools for Internet anonymity
Tools for Internet anonymity
In my previous post I wrote about the hacktivist group Anonymous and the importance of anonymity, which is the key for proper function of the group. To stay anonymous most of the members use Tor, so I�m going to write about Tor and one more tool used for internet anonymity, I2P, with the main goal of clearing some differences between those two.
The Onion Router, aka Tor (Figure 1) is free software which aims to allow its users to be untraceable on the internet. It attempts to do so by connecting their devices to the Tor network before forwarding their request to the actual destination. The Tor network is a volunteer network, consisting of several relays used to conceal a users location. Data packets in the Tor network dont use a direct path from source to destination; instead they use a randomly chosen pathway. To create a pathway, a circuit of encrypted connections through relays is build. Each relay decrypts a layer of encryption. That way every relay knows only from which relay it got data from and which relay its giving the data to. The final relay decrypts the innermost layer of encryption and sends the original data to its destination without revealing the source. There are sites that cant be accessed via Google but can be reached with Tor, such as .onion sites. These sites are short-lived and one must be up to date to know which sites are still working. For that reason, there are several .onion directories which contain many links to active sites, such as ahmia.fi.
The Onion Router, aka Tor (Figure 1) is free software which aims to allow its users to be untraceable on the internet. It attempts to do so by connecting their devices to the Tor network before forwarding their request to the actual destination. The Tor network is a volunteer network, consisting of several relays used to conceal a users location. Data packets in the Tor network dont use a direct path from source to destination; instead they use a randomly chosen pathway. To create a pathway, a circuit of encrypted connections through relays is build. Each relay decrypts a layer of encryption. That way every relay knows only from which relay it got data from and which relay its giving the data to. The final relay decrypts the innermost layer of encryption and sends the original data to its destination without revealing the source. There are sites that cant be accessed via Google but can be reached with Tor, such as .onion sites. These sites are short-lived and one must be up to date to know which sites are still working. For that reason, there are several .onion directories which contain many links to active sites, such as ahmia.fi.
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| Figure 1. Tor logo |
One thing to keep in mind is that Tor only protects your location, not information. It does not prevent you from sharing information that can be traced back to you. One such case is of Ross Ulbricht, the founder of Silk Road, a famous darkweb marketplace. The site relied on Tor to hide its users, and bitcoin as a currency, since it leaves no trail just like cash. The site was run by Ulbricht for two years, and became quite big before the government discovered him by connecting some old forum posts indirectly promoting Silk Road to his name. That and several other seemingly insignificant personal details, like references to works of the same Austrian economist, connected the accounts to him and led to his arrest.
An alternative to Tor is I2P or The Invisible Internet Project (Figure 2). Its main goal is also user anonymity but it achieves it in a slightly different way. I2P is an overlay network on top of the Internet. By default every computer that connects to the I2P network is not only a user but also a node (�router�), which means other users� traffic is relayed through it. That way the user�s traffic is mixed in and hidden. I2P uses a tunnel mechanism, with separate inbound and outbound tunnels, and the tunnels are often switched which prevents long-term interception. The transmitted information itself is encrypted on every hop, another layer within each tunnel, and a final layer from peer to peer. Just like with Tor, there are sites only accessible using I2P, called eepsites. For distributing routing and contact information securely, I2P uses its own network database. Each router is identified by a cryptographic Router Identity. These routers communicate with transport mechanisms like TCP and UDP. Client applications have their own cryptographic identifier which enables them to send and receive messages. Clients can connect to any router and lease tunnels that will be used for receiving and sending messages. Data sent is encrypted through three layers, used to verify the delivery of the message to the recipient; tunnel encryption where every message going through the tunnel is encrypted by the tunnel gateway to the tunnel endpoint; and inter router transport layer encryption.
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| Figure 2. I2P logo |
There are several differences between Tor and I2P. For example, Tor uses a centralized server for acquiring the information about nodes of the network, which leaves it vulnerable to DOS attacks, while on the other hand I2P passes the information from peer to peer, continuously updating the hash table called netDb. Next, since users on the Tor network only send their own traffic into the network, they are susceptible to correlation attacks, but I2P users relay general traffic and it masks their own. But for the same reason, Tor users have very low bandwidth overhead, since they do not have to act as a relay for other users� traffic like I2P users. Tor is also better built for scaling, so it does not suffer from growing user numbers, while I2P still has to address slowdown problems caused by a large user population. The I2P designers themselves admit that Tor is also more widespread, giving it more attention in the academic community, has more users and more funding.
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