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Tetsu IWATA Tohru YAGI Kaoru KUROSAWA
KASUMI is a block cipher which has been adopted as a standard of 3GPP. In this paper, we study the pseudorandomness of idealized KASUMI type permutations for adaptive adversaries. We show that ●the four-round version is pseudorandom and ●the six-round version is super-pseudorandom.
Tetsu IWATA Tohru YAGI Kaoru KUROSAWA
KASUMI is a blockcipher that forms the heart of the 3GPP confidentiality and integrity algorithms. In this paper, we study the security of the five-round KASUMI type permutations, and derive a highly non-trivial security bound against adversaries with adaptive chosen plaintext and chosen ciphertext attacks. To derive our security bound, we heavily use the tools from graph theory. However the result does not show its super-pseudorandomness, this gives us a strong evidence that the design of KASUMI is sound.