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

Abstract

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 introduced 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.

FPGA implementation of an optimized A5/3 encryption algorithm

“…The future works will mainly focus on the robustness enhancement of the KASUMI encryption algorithm, which is still largely used in countries using UMTS mobile networks. To achieve this objective, we consider this proposed optimized-architecture which can be combined with previous works [6][7][8] to increase data protection against the usual cryptanalysis attacks.…”

“…They where cryptanalyzed a few years later [1][2][3][4] and replaced by the A5/3 algorithm which was also cryptanalyzed [5]. However, considering that the A5/3 algorithm is until widely used in Universal Mobile Telecommunication Systems (UMTS) networks (to perform the f8 confidentiality and f9 integrity functions), investigations are still proposed to improve the security optimization of the KASUMI algorithm [6][7][8]. Therefore, A5/3 optimization is yet very relevant.…”

FPGA implementation of an enhanced chaotic-KASUMI block cipher

“…However, in the last decade KASAUMI security was the object of many cryptanalyzed attacks as mentioned in [3][4][5][6][7][8][9]. But, investigations are still proposed to improve the security and resistance of the KASUMI algorithm [10][11][12]. For this reason, we decided to try proposing a solution aiming to recover this problem.…”