Improved 2-round collision attack on IoT hash standard ASCON-HASH

Lightweight cryptography algorithms are a class of ciphers designed to protect data generated and transmitted by the Internet of Things. They typically have low requirements in terms of storage space and power consumption, and are well-suited for resource-limited application scenarios such as embedded systems, actuators, and sensors. The NIST-approved competition for lightweight cryptography aims to identify lightweight cryptographic algorithms that can serve as standards. Its objective is to enhance data security in various scenarios. Among the chosen standards for lightweight cryptography, ASCON has been selected. ASCON-HASH is a hash function within the ASCON family. This paper presents a detailed analysis of the differential characteristics of ASCON-HASH, utilizing the quadratic S-box. Additionally, we employ message modification techniques and ultimately demonstrate a non-practical collision attack on the 2-round ASCON-HASH, requiring a time complexity of 2⁹⁸ hash function calls.