
Research
Research Interests
My research interests lie in the field of information security and include:
 Cryptology, especially design and cryptanalysis of symmetrickey ciphers
 Malicious software (malware) analysis
 Software copy protection and digital watermarking
 Network security
 Digital forensics and investigation
I am the coordinator of the Information Security Research Group (ISRG).
Research Papers
Refereed Publications
 F. Mirza and S. Murphy, “An Observation on the Key Schedule of Twofish”, 2nd Advanced Encryption Standard (AES) Workshop Proceedings, Rome, 1999. [slides from my presentation at the University of Bergen, Norway]
The 16byte block cipher Twofish was proposed as a candidate for the Advanced Encryption Standard (AES). This paper notes the following two properties of the Twofish key schedule. Firstly, there is a nonuniform distribution of 16byte whitening subkeys. Secondly, in a reduced (fixed Feistel round function) Twofish with an 8byte key, there is a nonuniform distribution of any 8byte round subkey. An example of two distinct 8byte keys giving the same round subkey is given.
 S. R. Blackburn, K. Brincat, F. Mirza, and S. Murphy, “Cryptanalysis of ‘Labyrinth’ Stream Cipher”, IEE Electronics Letters, 38(12):12201221, 1998.
The paper cryptanalyses the stream cipher Labyrinth, a cipher recently proposed by Bo Lin and Simon Shepherd. Given only 2^{30} known bits of keystream, the 119bit key of Labyrinth is recovered in under a second of computation using a DEC Alpha.
Other Papers
 F. Mirza, “Block Ciphers and Cryptanalysis”, March 1998.
This report gives a basic introduction to block cipher design and analysis. The concepts and design principles of block ciphers are explained, particularly the class of block ciphers known as Feistel ciphers. Some modern block cipher cryptanalysis methods are demonstrated by applying them to variants of a weak Feistel cipher called Simplified TEA (STEA), which is based on the Tiny Encryption Algorithm (TEA).
 F. Mirza, “Linear and SBox Pairs Cryptanalysis of the Data Encryption Standard”, April 1997.
DES was developed by IBM in the early 1970's, and is currently the most widelyused data encryption algorithm. However, for over 12 years since its standardisation in 1977, nobody had found a method of breaking DES. Now, 20 years later, there are three published methods of finding the key in less time than exhaustive keysearch. In this report, we provide descriptions of DES and two of the most recent attacks on DES. We will show how DES can be implemented in the C programming language, and optimised to run efficiently on 32bit computers. We also implement algorithms from the two cryptanalysis methods, and provide experimental proof that the attacks work.

