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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Relative Compromise Of Statistical Databases, M Miller, Jennifer Seberry
Relative Compromise Of Statistical Databases, M Miller, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
Statistical databases are databases in which only statistical type of queries are allowed. The results of the statistical queries are intended for statistical use only. However, it has been shown that using only statistical queries it is often possible to infer an individuals's value of a protected field (e.g, using various types of trackers). In such a case we say that the database has been (positively) compromised. Various types of compromise have been studied but until now attention has centred on the inference of exact information from permitted queries. In this paper we introduce a new type of compromise, the …
Sbibd(4k², 2k² + K, K² + K) And Hadamard Matrices Of Order 4k² With Maximal Excess Are Equivalent, Jennifer Seberry
Sbibd(4k², 2k² + K, K² + K) And Hadamard Matrices Of Order 4k² With Maximal Excess Are Equivalent, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
We show that an SBIBD(4k², 2k² + k, k² + k) is equivalent to a regular Hadamard matrix of order 4k² which is equivalent to an Hadamard matrix of order 4k² with maximal excess. We find many new SBIBD(4k², 2k² + k, k² + k) including those for even k when there is an Hadamard matrix of order 2k (in particular all 2k ≤ 210) and k є {1, 3, 5,...,29,33,...,41,45,51,53,61,...69,75,81,83,89,95,99,625,32m,25. 32m, m ≥ 0}.
User Unique Identification, Terry Jones, Mike Newberry, Jennifer Seberry
User Unique Identification, Terry Jones, Mike Newberry, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
Traditionally, users have been authenticated by asking them to provide some form of password. This password has been stored securely in the computer and used to check the identity of the user at various times, such as when they first log on. However such authentication only proves that the challenged user knows the password - it doesn't identify the user. This has often been a security problem in time-shared computer installations, when unauthorised users (the proverbial "hackers") have obtained the passwords of valid users and used these to penetrate the site's security. This has led to much work to identify …
A Survey Of Base Sequences, Disjoint Complementary Sequences And Od(4t; T, T, T, T), Gavin Cohen, David Rubie, Jennifer Seberry, Christos Koukouvinos, Stratis Kounias, Mieko Yamada
A Survey Of Base Sequences, Disjoint Complementary Sequences And Od(4t; T, T, T, T), Gavin Cohen, David Rubie, Jennifer Seberry, Christos Koukouvinos, Stratis Kounias, Mieko Yamada
Faculty of Informatics - Papers (Archive)
We survey the existence of base sequences, that is four sequences of lengths m + p, m + p, m, m, p odd with zero auto correlation function which can be used with Yang numbers and four disjoint complementary sequences (and matrices) with zero non-periodic (periodic) autocorrelation function to form longer sequences. We survey their application to make orthogonal designs OD(4t; t, t, t, t). We give the method of construction of OD(4t; t, t, t, t) for t = 1,3,..., 41, 45,...,65, 67, 69, 75, 77, 81, 85, 87, 91, 93, 95, 99, 101, 105, 111, 115, 117, 119, …
Experience Of Using A Type Signature Password System For User Authentication In A Heavily Used Computing Environment, Mike Newberry, Jennifer Seberry
Experience Of Using A Type Signature Password System For User Authentication In A Heavily Used Computing Environment, Mike Newberry, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
This paper describes a user authentication system based around the user's type signature, a statistical measure of the user's typing style. It was tested on two heavily loaded computers.
A Multilevel Encryption Scheme For Database Security, Thomas Hardjono, Jennifer Seberry
A Multilevel Encryption Scheme For Database Security, Thomas Hardjono, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
An encryption scheme is proposed which allows a hierarchical organization of keys used to encrypt and decrypt data stored in databases. The scheme uses the same method as the RSA cryptosystem [RISH78] to encrypt and decrypt data, with additional restrictions on the availability of the encryption information to the public. Its security is based on the Discrete Logarithm problem [DIHE76] which is known to be NPI. Each user is issued a key which is used for decryption and user clearance verification.
Pseudo-Random Sequence Generators Using Structured Noise, R S. Safavi-Naini, Jennifer Seberry
Pseudo-Random Sequence Generators Using Structured Noise, R S. Safavi-Naini, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
Stream ciphers use the output of a Pseudo-Random (PR) generator to mask the information stream. The security of these cipher systems ultimately depends on the structure of the PR generator. There are some minimum necessary criteria such as long period, flat statistical distribution and high linear complexity that the PR generator of a stream cipher system should satisfy to resist the basic cryptanalytic attacks on such systems. We propose a class of PR generators using the coset elements of a Reed-Muller code. The linear Complexity of these generators is analysed and conditions that assure the highest possible linear complexity for …
Cryptographic Techniques, Jennifer Seberry
Cryptographic Techniques, Jennifer Seberry
Faculty of Informatics - Papers (Archive)
The public key cryptosystem published by Diffie and Hellman in 1976 is still of great interest today. Of the public key systems that have been proposed the RSA scheme of Rivest, Shamir and Adelman is of most current interest. We shall briefly describe this system (more can be found in references 2 and 7) and then describe a method to obtain suitable primes for use in the scheme.
Products Of Hadamard Matrices, Williamson Matrices And Other Orthogonal Matrices Using M-Structures, Jennifer Seberry, Mieko Yamada
Products Of Hadamard Matrices, Williamson Matrices And Other Orthogonal Matrices Using M-Structures, Jennifer Seberry, Mieko Yamada
Faculty of Informatics - Papers (Archive)
The new concept of M-structures is used to unify and generalize a number of concepts in Hadamard matrices including Williamson matrices, Goethals-Seidel matrices, Wallis-Whiteman matrices and generalized quaternion matrices. The concept is used to find many new symmetric Williamson-type matrices, both in sets of four and eight, and many new Hadamard matrices. We give as corollaries "that the existence of Hadamard matrices of orders 4g and 4h implies the existence of an Hadamard matrix of order 8gh" and "the existence of 'Williamson type matrices of orders u and v implies the existence of 'Williamson type matrices of order 2uu". This …