Grover on Korean Block Ciphers

• Published in: Applied sciences Vol. 10; no. 18; p. 6407
• Main Authors: Jang, Kyoungbae, Choi, Seungju, Kwon, Hyeokdong, Kim, Hyunji, Park, Jaehoon, Seo, Hwajeong
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01-09-2020
• Subjects: Algorithms; block ciphers; CHAM; Computers; Cryptography; Grover search algorithm; HIGHT; Internet of Things; LEA; Lightweight; quantum circuits; Quantum computers; Quantum computing; Qubits (quantum computing); Search algorithms; Security; Software
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app10186407

The Grover search algorithm reduces the security level of symmetric key cryptography with n-bit security level to O(2n/2). In order to evaluate the Grover search algorithm, the target block cipher should be efficiently implemented in quantum circuits. Recently, many research works evaluated required quantum resources of AES block ciphers by optimizing the expensive substitute layer. However, few works were devoted to the lightweight block ciphers, even though it is an active research area, nowadays. In this paper, we present optimized implementations of every Korean made lightweight block ciphers for quantum computers, which include HIGHT, CHAM, and LEA, and NSA made lightweight block ciphers, namely SPECK. Primitive operations for block ciphers, including addition, rotation, and exclusive-or, are finely optimized to achieve the optimal quantum circuit, in terms of qubits, Toffoli gate, CNOT gate, and X gate. To the best of our knowledge, this is the first implementation of ARX-based Korean lightweight block ciphers in quantum circuits.