Bit‐level evaluation of piccolo block cipher by satisfiability problem solver

In the field of symmetric key cryptography, security against distinguishing attacks is one crucial requirements. With advancements in computing capabilities and cryptanalysis techniques recent years, more efficient methods have been proposed for exploring distinguishers using Mixed-Integer Linear Programing (MILP) or satisfiability problem (SAT), thereby updating bounds various ciphers. Piccolo a lightweight block cipher at CHES 2011, with support 80-bit 128-bit keys. Designers undergone rough evaluation differential, impossible related-key differential attacks, based on nibble-wise estimations due to limitation computational resource. Here, authors perform bit-level evaluations integral by leveraging SAT-based approaches. For first time, succeed identifying optimal distinguisher 6 rounds single setting, 10/12 setting keys, respectively. find up 7 rounds. Although number attacked same as that previous attack, 56th ordered distinguisher, which enable reducing data complexity from 263 256. As result, 7-round differentials evaluation.