 Hi, I'm Johan Damen and I want to draw your attention to our paper German on the deck. This is the paper we submitted to Asia-Crypt and it got happily accepted and it will be presented by one of our co-authors, Sjil van Asch, on Wednesday at 8.50 in the ballroom B in the session on symmetric crypto. It's a joint work with old-time collaborator Ronny van Keer, the catch-up team, Seth Hoffert, who also is in our team since a few years and has always great ideas. Bachelor student Norika Bakueti, who was at Radboot and did an internship and whose internship led to this work, and last but not least, Sjil van Asch, who will actually present the paper. Okay, what is it about? It's about refactoring symmetric crypto. Let's take a look at a metaphor. A metaphor for the field of symmetric crypto is this sea landscape. So we have two worlds, actually, and the first world is above the water, and that's a world where everything is nice and clean, and the world base itself on ideal primitives. And these ideal primitives, they're represented by the water surface, so the water surface is nice and smooth. And if that is the case, then we can do nice things about the water, like make provably secure schemes, and these schemes, for their provable security, they base themselves on some assumptions on the water surface, so on the primitives, and the primitives are typically a block cipher. It's like dominantly the block cipher. But under the water, there is another world. And that is the world of cryptanalysis, of people that try to find weaknesses in block ciphers, try to specify attacks, or try to prove properties of block ciphers. And these are two different worlds, and it's a nice interface, and this interface has given us a lot of nice modes, and also nice block ciphers, and it divides the world of symmetric crypto into nice parts. But there are some constructions that do not fit this nice image. And one such construction is something, I go back to my work with Vincent Hyman, as you know we did together the AES, but later we did some other work, and one of these other things was Pelikan Mach. And Pelikan Mach is a Mach function based on AES, Heindalen, that only requires four rounds per additional block of plaintext. So additional block of message to Mach, and so it's about two and a half times faster than AES. So the problem of this construction is it cannot be reduced to the PRP security of AES, but you have to really do cryptanalysis. But the gain is that you get much more efficient Mach function. Another example is the monkey duplex. So monkey duplex. In general the duplex can be proven secure if you assume a random permutation, if you believe that such a thing exists, it's a kind of controversial issue. But monkey duplex is not anymore because you use different number of rounds and there's no way you can model this underlying permutation as being ideal. The monkey duplex is serial, more parallel function is farfalle, so it's a construction to build a function with variable length input and variable length output based on a permutation, in this case symbolized by F. And it has also several instances, cravat and zoof, cravat based on the Kacak F permutation and Kacak P permutation, and zoof based on Zudu are more recent permutations, a bit more lightweight. And all these things they require for their security cryptanalysis. So we thought maybe it's a good idea to kind of put the border elsewhere and put the border at a level where the underlying primitive can handle variable length messages and make one function like that and build modes on top of that. And this interface is a deck function. So a deck function is something that takes as input a sequence of strings of all arbitrary length and generates an output string also of arbitrary length. And using this deck function, we can build very efficient modes and these modes can be proven secure with reasonably simple proofs, assuming that the underlying deck function is hard to distinguish from a random oracle. And that is actually what the paper is about, that's also what the talk is about. I hope we will show up in large numbers, thank you.