Biclique Cryptanalysis of Reduced-Round Piccolo Block Cipher
Piccolo is a lightweight block cipher, with a fixed 64-bit block size and variable key length 80- or 128-bit, which was proposed at CHES 2011. The iterative structure of Piccolo is a variant of Generalized Feistel Network. The transformation utilizing different-size-word based permutation improves diffusion property of Piccolo and the simple key schedule algorithm reduces hardware costs. By analyzing the distribution of the subkeys, we present a biclique cryptanalysis of full round Piccolo-80 without postwhitening keys and 28-round Piccolo-128 without prewhitening keys. The attacks are respectively with data complexity of 248 and 224 chosen ciphertexts, and with time complexity of 278.95 and 2126.79 encryptions.
KeywordsLightweight block cipher Piccolo Meet-in-the-middle Biclique cryptanalysis Complexity
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