Diffusion Analysis of F-function on KASUMI Algorithm
Rizki Yugitama, Bety Hayat Susanti, Magfirawaty Magfirawaty · ISICO 2013 · 2013
There are several aspects and criteria that should be considered for designing Feistel block cipher, including: block size, key si ze, number of rounds, subkey generation algorithm, round function, fast software encryption/decryption, and ease of analysis. The function F is the heart of Fe istel block ciphers. It provides confusion property that makes the relationship betw een ciphertext and encryption key as statistically complex as possible . One obvious property is that F must be nonlinear. The more non linear F, th e more difficult any type of cryptanalysis be. KASUMI is the Feistel block ciphe r that used in UMTS, GSM, and GPRS mobile communication systems. F-function component of KASUMI composed of FI, FL, and FO functions. In this paper, we analyzed the diffusion of F-funct ion of KASUMI to determine its cryptographic strength using Strict A valanche Criterion (SAC) and Bit Independence Criterion (BIC). The SAC test resul t showed that FIsubfunction has smallest relative error. Whilst, th e BIC test results show that FL-subfunction has a zero value.