ChaCha: Development and modification of Salsa20 in modern cryptographic systems

Abstract

The study reviewed the ChaCha20 stream cypher as the successor to the Salsa20 algorithm, emphasising development, technical features, and application in modern cryptosystems. The research relevance is determined by the widespread implementation of ChaCha20 in security protocols (TLS 1.3, VPN, etc.) due to its high performance in software implementations and resistance to cryptanalysis. The study aimed to analyse the evolution of ChaCha Salsa20, compare it with other cyphers, and summarise the latest achievements in terms of modifications and performance. The study used methods of analysing literary sources and experimental data on the speed and resistance of cyphers. The main results included a highlighted history of ChaCha’s creation based on Salsa20 and improving diffusion per round, a detailed description of the algorithm’s structure (4×4 state matrix, addition-rotation-XOR operations) and its cryptographic strength (no practical attacks on the full 20-round version). The advantages of ChaCha20 over the Advanced Encryption Standard (AES) in a software environment are demonstrated; in particular, on platforms without AES hardware acceleration, ChaCha20 runs up to 3 times faster with an equivalent level of security. The implementation of ChaCha20-Poly1305 in TLS and WireGuard is considered, as well as the use of XChaCha for extended nonces and the Adiantum algorithm for disk encryption on mobile devices. Modern modifications of ChaCha (e.g., increasing the number of rounds) and their impact on performance and security were analysed. The practical value of the review is determined by a summary of modern experience with ChaCha20, which can be used for the ion of cryptographic algorithms in resource-constrained systems and for further research in the field of stream cyphers.