Mitsuri Matsui

Bio: Mitsuri Matsui is an academic researcher from Mitsubishi Electric. The author has contributed to research in topics: Linear cryptanalysis & Block cipher. The author has an hindex of 2, co-authored 2 publications receiving 244 citations.

New structure of block ciphers with provable security against differential and linear cryptanalysis

Abstract: We introduce a methodology for designing block ciphers with provable security against differential and linear cryptanalysis. It is based on three new principles: change of the location of round functions, round functions with recursive structure, and substitution boxes of different sizes. The first realizes parallel computation of the round functions without losing provable security, and the second reduces the size of substitution boxes; moreover, the last is expected to make algebraic attacks difficult. We also give specific examples of practical block ciphers that are provably secure under an independent subkey assumption and are reasonably fast in hardware as well as in software implementation.

New Structure of Block Ciphers with Provable Security against Differential and Linear Cryptanalysis

Abstract: We introduce a methodology for designing block ciphers with provable security against differential and linear cryptanalysis. It is based on three new principles: change of the location of round functions, round functions with recursive structure, and substitution boxes of different sizes. The first realizes parallel computation of the round functions without losing provable security, and the second reduces the size of substitution boxes; moreover, the last is expected to make algebraic attacks difficult. We also give specific examples of practical block ciphers that are provably secure under an independent subkey assumption and are reasonably fast in hardware as well as in software implementation.

Fast Software Encryption

Abstract: RC6 has been submitted as a candidate for the Advanced Encryption Standard (AES). Two important features of RC6 that were absent from its predecessor RC5 are a quadratic function and a fixed rotation. By examining simplified variants that omit these features we clarify their essential contribution to the overall security of RC6.

Twofish : A 128-bit block cipher

Abstract: Twofish is a 128-bit block cipher that accepts a variable-length key up to 256 bits. The cipher is a 16-round Feistel network with a bijective F function made up of four key-dependent 8-by-8-bit S-boxes, a fixed 4-by-4 maximum distance separable matrix over GF(2), a pseudo-Hadamard transform, bitwise rotations, and a carefully designed key schedule. A fully optimized implementation of Twofish encrypts on a Pentium Pro at 17.8 clock cycles per byte, and an 8-bit smart card implementation encrypts at 1660 clock cycles per byte. Twofish can be implemented in hardware in 14000 gates. The design of both the round function and the key schedule permits a wide variety of tradeoffs between speed, software size, key setup time, gate count, and memory. We have extensively cryptanalyzed Twofish; our best attack breaks 5 rounds with 2 chosen plaintexts and 2 effort.

New Block Encryption Algorithm MISTY

Abstract: We propose secret-key cryptosystems MISTY1 and MISTY2, which are block ciphers with a 128-bit key, a 64-bit block and a variable number of rounds. MISTY is a generic name for MISTY1 and MISTY2. They are designed on the basis of the theory of provable security against differential and linear cryptanalysis, and moreover they realize high speed encryption on hardware platforms as well as on software environments. Our software implementation shows that MISTY1 with eight rounds can encrypt a data stream in CBC mode at a speed of 20Mbps and 40Mbps on Pentium/100MHz and PA-7200/120MHz, respectively. For its hardware performance, we have produced a prototype LSI by a process of 0.5Μ CMOS gate-array and confirmed a speed of 450Mbps. In this paper, we describe the detailed specifications and design principles of MISTY1 and MISTY2.

KLEIN: a new family of lightweight block ciphers

Abstract: Resource-efficient cryptographic primitives are essential for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while its hardware implementation can be compact as well.

KLEIN: A New Family of Lightweight Block Ciphers

Abstract: Resource-efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role as a building block for security protocols. In this paper, we describe a new family of lightweight block ciphers named KLEIN, which is designed for resource-constrained devices such as wireless sensors and RFID tags. Compared to the related proposals, KLEIN has advantage in the software performance on legacy sensor platforms, while its hardware implementation can be compact as well.