Muladi Muladi, Soraya N. Mustika, Achamd Hamdan, Abd Kadir Mahamad, Anik Nur Handayani, Satrio Dwi Sanjaya
Salsa20 and Chacha20 are two stream ciphers developed using bit permutation processes on keystream matrices. Both are also known as Latin dance stream ciphers based on the nature of the bit rotation in words to the right or left. Chacha20 is a stream cipher that has been widely implemented to improve data security from cryptanalysis attacks. Many studies have demonstrated the strength of this cipher, but improvements are needed to anticipate vulnerabilities from different types of attacks. This study further develops both stream ciphers by modifying the Quarter Round (QR) function. The modifications made include changing the rotation constant by using prime numbers (13, 11, 7, 5), tested through simulations using Matlab and statistical tests using the NIST Statistical Test Suite (NSTS). The results showed that the proposed rotation constants of (13, 11, 7, 5) have 25% faster encryption time and 44% decryption time compared to (16, 12, 8, 7) in Chacha20/20 with almost equal symbol diffusion characteristics. © 2025 IEEE.
State University of Malang, Electronic System Eng. Study Program, Malang, Indonesia; University Tun Hussein Onn, Fac. of Electronic and Electrical Eng., Batu Pahat, Malaysia; National Yang Ming Chiao Tung Univ., Hsinchu City, Taiwan
