Title: ANONYMITY LAYER

Anonymity Layer

On top of this base layer lays the anonymity-preserving transport layer that is in terms of GNUnet terminology the GNUnet’s anonymity protocol or GAP, in short. GAP is mainly useful for requesting files in an anonymous manner. By anonymity in terms of GAP we address the state in which an adversary is not able to prove (with likelihood greater than p) that a user is sender or recipient, respectively, of a message, which has been transmitted through the GNUnet network. This needs to hold even if the adversary is able to eavesdrop all connections within the network or able to alter transmitted data. Additionally, the anonymity must not be broken, if a set of members of the GNUnet network, which might be of almost arbitrary size, collaborates with the adversary, that is providing data to the adversary or be controlled by him.

Essentially, anonymity of a user is achieved by rerouting the requests and responses over different users of the GNUnet. In contrast to the proxy approach where anonymity for users is achieved by means of rerouting traffic over a third party, GNUnet is more similar to the Crowds approach. Anonymity for a user in GNUnet is achieved by acting as relay for other users. Own messages can then be hidden in foreign traffic. 

In order to achieve anonymity, that is p<1, a user needs to receive messages from at least one neighbour which does not collaborate with the adversary. In that case, the adversary cannot be sure, whether the data received from the user has been initiated by the user herself or is a rerouted data from another user. This is achieved due to encryption on GNUnet’s base layer.