In Pursuit of Privacy: An Introduction to Anonymization Technologies

Privacy in the age of pervasive computing and networking is a very hard topic to fully grasp. Any serious attempt at discussing it must take many different angles into account. User interactions grow richer month after month, and due to Big Data techniques, more information about each individual is known to third parties than to the person in question themselves; this is illustrated in the concept of inverse privacy [4]. What is a user to do to keep at least a basic expectation of privacy? Due to the pervasive analysis, a user can only expect their actions to remain private by becoming anonymous-By incorporating into their everyday activities Privacy Enhancement Technologies (PETs) that avoid each of their actions to be linked into a wide-encompassing profile. Anonymity is often achieved via confusion and blending in the crowd: If a person wants their messages to be concealed, they usually first need to identify and use an active network carrying traffic in which to hide; implementations starting with Chaum’s mix networks [2] expressly assume an existing level of traffic needed for anonymous messages to be hidden. Mix networks are based on public key cryptography, first delineated in 1976 [3]. In a nutshell, each message is encrypted with the public key of several intermediaries, forming a route that must be followed in order to reach its destination. That is, having users A, B, C, D and E, each of whom has an asymmetric key pair {KA, KA}, {KB, KB} etc. and denoting encryption and decryption of a clear-text message M to a secret-containing cyphertext S respectively as S=Enc(M; KA) (which anybody can do, as the public key KA is known by every actor) and M=Dec(S; KA) (which only A can perform, as only this actor has knowledge of KA).