Update (Sept 21, 2018): Negligible functions map to the real positive numbers.
Oct 17: Update on the Exercise Sheet for clarity.
Oct 17: Second update on the Exercise Sheet for a nicer Feistel construction figure and correcting a typos in the definition of quadratic-key PRF: It was using the letter f in positions where it should use letter g.
Oct 17: Third update on the Feistel description.
This exercise sheet is aimed at helping to understand security models, i.e., encoding security properties as indistinguishability between two games. In particular, the goal is to understand the UNF-CMA model introduced in the lecture and the properties that it encodes. The exercise sheet discusses strengthenings and weakenings of the definition.
Oct 31: Minor update to clarify the definition of the first MAC scheme m' by using a for loop; added a missing prime
Nov 2: Added a missing \tau in the verification algorithm
This exercise sheet studies candidate constructions for authenticated encryption. The Lecture Notes 10 are highly relevant for this exercise sheet. Please check for updates of the Lecture Notes 10, since those updates might help with exercise 46/47.
Update Nov 21, 3:00PM: Fixed Error in Exercises 46 and 47, code
equivalence: The reduction Rx with oracle access should be code
equivalent to the game AE1s itself.