Seminar on Security of Embedded Electronic Systems

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Guido Bertoni

Keccak, Permutation based crypto and security aspects

Permutation based cryptography is a recent chapter in the field of symmetric key primitives. There are different advantages in the use of permutation based cryptography. A single instance of a permutation can be used to cover all the needs of the symmetric key cryptography (encryption, key derivation, hash and full domain hash, authenticated encryption, MAC ). It is possible to trade dynamically security for performances without the need of changing the given permutation. The design of a permutation could be simpler compared to a block cipher, there is no need of having an efficient inverse. Protection against side channel attacks could be reached easily.

During the talk there will be an introduction of the sponge construction, motivation behind the proposal, how to use it in different context and an overview of other permutation based ciphers. A special focus will be dedicated to the side channel countermeasure aspects. Keccak and the recent proposals Ketje and Keyak are used as practical examples of permutation based algorithms.

The content of the talk is the result of a fruitful collaboration with Joan Daemen, Michael Peeters, Gilles Van Assche and Ronny Van Keer.