Narrow-Bicliques: Cryptanalysis of Full IDEA

摘要: We apply and extend the recently introduced biclique framework to IDEA for first time describe an approach noticeably speed-up key-recovery full 8.5 round IDEA. We also show that block cipher cryptanalysis not only obtains results on more rounds, but improves data complexities over existing attacks. consider 7.5 rounds of demonstrate a variant works with practical complexity. The conceptual contribution is narrow-bicliques technique: independent-biclique extended ways allow significantly reduced complexity everything else being equal. For this we use available degrees freedom as known from hash narrow relevant differential trails. Our high computational complexity, does threaten in any way, yet techniques are practically verified large extent.