Integral Distinguishers of the Full-Round Lightweight Block Cipher SAT_Jo

Integral cryptanalysis based on division property is a powerful cryptanalytic method whose range of successful applications was recently extended through the use of Mixed-Integer Linear Programming (MILP). Although this technique was demonstrated to be efficient in specifying distinguishers of reduced round versions of several families of lightweight block ciphers (such as SIMON, PRESENT, and few others), we show that this method provides distinguishers for a full-round block cipher SAT_Jo. SAT_Jo cipher is very similar to the well-known PRESENT block cipher, which has successfully withstood the known cryptanalytic methods. The main difference compared to PRESENT, which turns out to induce severe weaknesses of SAT_Jo algorithm, is its different choice of substitution boxes (S-boxes) and the bit-permutation layer for the reasons of making the cipher highly resource-efficient. Even though the designers provided a security analysis of this scheme against some major generic cryptanalytic methods, an application of the bit-division property in combination with MILP was not considered. By specifying integral distinguishers for the full-round SAT_Jo algorithm using this method, we essentially disapprove its use in intended applications. Using a 30-round distinguisher, we also describe a subkey recovery attack on the SAT_Jo algorithm whose time complexity is about 2 66 encryptions (noting that SAT_Jo is designed to provide 80 bits of security). Moreover, it seems that the choice of bit-permutation induces weak division properties since replacing the original bit-permutation of SAT_Jo by the one used in PRESENT immediately renders integral distinguishers inefficient.

Fast Search of Lightweight Block Cipher Primitives via Swarm-like Metaheuristics for Cyber Security

With the construction and improvement of 5G infrastructure, more devices choose to access the Internet to achieve some functions. People are paying more attention to information security in the use of network devices. This makes lightweight block ciphers become a hotspot. A lightweight block cipher with superior performance can ensure the security of information while reducing the consumption of device resources. Traditional optimization tools, such as brute force or random search, are often used to solve the design of Symmetric-Key primitives. The metaheuristic algorithm was first used to solve the design of Symmetric-Key primitives of SKINNY. The genetic algorithm and the simulated annealing algorithm are used to increase the number of active S-boxes in SKINNY, thus improving the security of SKINNY. Based on this, to improve search efficiency and optimize search results, we design a novel metaheuristic algorithm, named particle swarm-like normal optimization algorithm (PSNO) to design the Symmetric-Key primitives of SKINNY. With our algorithm, one or better algorithm components can be obtained more quickly. The results in the experiments show that our search results are better than those of the genetic algorithm and the simulated annealing algorithm. The search efficiency is significantly improved. The algorithm we proposed can be generalized to the design of Symmetric-Key primitives of other lightweight block ciphers with clear evaluation indicators, where the corresponding indicators can be used as the objective functions.