Lecture Notes Cryptographic Protocols

ii iii Preface In this course, we focus on asymmetric techniques for cryptographic protocols, also considering proofs of security for various constructions. Motivating example: 'Sinterklaaslootjes trekken' is a Dutch tradition for buying presents and writing little poems, see, The same tradition is also known as " Secret Santa " , and a lot of websites and programs are available to help people doing such drawings over the internet, see, e.g., the " Secret Santa Name Picker " at http://www.tenasoft.com/secretsanta/. The interesting question is how to do this securely?! That is, without trusting the website or program providing this service, but with the guarantee that indeed a random drawing is performed, corresponding to a random permutation without fixed points, and such that each participant learns nothing except who he or she is a Secret Santa for. To be elaborated. Bibliographic notes flagged with a sign in the margin (like this paragraph) still need to checked/extended. Text still to be extended at a few places.