Reducing the time required by KASUMI to generate output by modifying the FL and FI functions

Raja Muthalagu, Subeen Jain
2018 Iran Journal of Computer Science  
KASUMI is an eight-round Fiestel network that produces 64-bit output data from 64-bit input data using a 128-bit key. Three functions, FL, FO, FI , are involved in each round and each function has its respective keys KL, KO, KI. This work proposed the modifications in existing KASUMI block cipher, which can reduce time delay for generating 64-bit encrypted data. Also, we proposed a modification in FL functions: FL(a) and FL(b) of the existing KASUMI block cipher. Rijndael's 32-bit S-box is
more » ... duced in FL (a) function of standard FL function so that it can only work with 16-bit data. The second modification is introduced in the FL(b) function by adding a third stage where XOR and shift operations are involved before the final concatenation of two 16-bit data inside the standard FL function. In addition, the FI function uses S7 and S9 tables only one time instead of two times in the existing KASUMI block cipher, which leads to reduce the overall time delay. The performance improvement of the proposed algorithm over the conventional algorithm is verified by simulation results.
doi:10.1007/s42044-018-0017-2 fatcat:s677n6ig7zaorftsbldwkmlk44