Howard M. Heys

Learn More
In this paper, we present a detailed tutorial on linear cryptanalysis and differential cryptanalysis, the two most significant attacks applicable to symmetric-key block ciphers. The intent of the paper is to present a lucid explanation of the attacks, detailing the practical application of the attacks to a cipher in a simple, conceptually revealing manner(More)
In information security, message authentication is an essential technique to verify that received messages come from the alleged source and have not been altered. A key element of authentication schemes is the use of a message authentication code (MAC). One technique to produce a MAC is based on using a hash function and is referred to as an HMAC. Message(More)
In this paper we examine a class of product ciphers referred to as substitution-permutation networks. We investigate the resistance of these cryptographic networks to two important attacks: differential cryptanalysis and linear cryptanalysis. In particular, we develop upper bounds on the differential characteristic probability and on the probability of a(More)
In this paper, we examine the digital hardware design and implementation of a novel compact block cipher, referred to as PUFFIN, that is suitable for embedded applications. An implementation of PUFFIN targeted to ASIC technology is considered. The proposed block cipher is designed to have a 64-bit block size, a 128-bit key, and is capable of both encryption(More)
Abstract — This paper develops analytical models for the avalanche characteristics of a class of block ciphers usually referred to as substitution-permutation encryption networks or SPNs. An SPN is considered to display good avalanche characteristics if a one bit change in the plaintext input is expected to result in close to half the ciphertext output bits(More)
In this paper, we examine the energy efficiency of symmetric key cryptographic algorithms applied in wireless sensor networks (WSNs) and in our study we consider both stream ciphers and block ciphers. We derive the computational energy cost of the ciphers under consideration by comparing the number of CPU cycles required to perform encryption. After(More)
In this paper, we present a new block cipher, referred as PUFFIN2, that is designed to be used with applications requiring very low circuit area. PUFFIN2 is designed to be implemented exclusively with CMOS technologies and in a serialized architecture, so that the maximum reuse of hardware components is achieved resulting in a very compact implementation.(More)
Linear feedback shift registers (LFSRs) and nonlinear feedback shift registers (NLFSRs) are major components of stream ciphers. It has been shown that, under certain idealized assumptions, LFSRs and LFSR-based stream ciphers are susceptible to cryptanalysis using simple power analysis (SPA). In this paper, we show that simple power analysis can be(More)
In this Letter, we examine the application of linear cryptanalysis to the RC5 private-key cipher and show that there are expected to be weak keys for which the attack is applicable to many rounds. It is demonstrated that, for the 12-round nominal RC5 version with a 64-bit block size and a 128-bit key, there are 2 28 weak keys for which only about 2 17 known(More)