The application of coding theory to security scenarios is studied. Authentication systems are introduced that are based on algebraic codes and provide high protection against an intruder's impersonation and substitution attacks. It is shown that a subliminal channel can be embedded into these systems and that there is a trade-off between the authentication capability, subliminal capacity and er...

shah ismail established a dynasty in iran on the premises of nationality and religion. to establish national unity in iran, he announced shia as the official religion. his goal was to strengthen iranian national bonds. the presence of uzbeks in the east and ottomans in the west made it necessary that iranian people reinforce their feeling of patriotism and love for they homeland. shah ismail be...

The Bluetooth standard has a provision for mutual authentication of connecting devices but not their actual users and allows access control during connection setup only. We propose a user authorization and pairing (UAP) application, that has the ability to perform authentication and authorization of users using role based model. The pairing procedure, which exchanges link key between devices, i...

In this paper, information theoretic cryptography is discussed based on conditional Rényi entropies. Our discussion focuses not only on cryptography but also on the definitions of conditional Rényi entropies and the related information theoretic inequalities. First, we revisit conditional Rényi entropies, and clarify what kind of properties are required and actually satisfied. Then, we propose ...

Recent development in the Internet and Web based technologies require faster communication of multimedia data in a secure form. A number of encryption schemes for MPEG have been proposed. In this paper, we evaluate the compression performance of JPEG which has been encrypted with the zig-zag permutation algorithm, suggest a security enhancement to the scheme, and propose an alternative to entro...

The ways the threshold parameter can be modified after the setup of a secret sharing scheme is the main theme of this work. The considerations are limited to the case when there are no secure channels. First we motivate the problem and discuss methods of threshold change when the dealer is still active and can use broadcasting to implement This work was supported by the European Commission unde...

With the advent of Internet image authentication has become a central part of research in security. Since JPEG has recommended discrete cosine transform as one of the steps in image compression systems, a hash function which utilizes discrete cosine decomposition is desirable. In this paper, we propose a discrete cosine based hash function which distinguishes acceptable level of compression fro...