In this paper, new software and hardware designs for the NTRU Public Key Cryptosystem are proposed. The first design attempts to improve NTRU's polynomial multiplication through applying techniques from the Chinese Remainder Theorem (CRT) to the convolution algorithm. Although the application of CRT shows promise for the creation of the inverse polynomials in the setup procedure, it does not provide any benefits to the procedures that are critical to the performance of NTRU (public key creation, encryption, and decryption). This research has identified that this is due to the small coefficients of one of the operands, which can be a common misunderstanding. The second design focuses on improving the performance of the polynomial multiplications within NTRU's key creation, encryption, and decryption procedures through hardware. This design exploits the inherent parallelism within a polynomial multiplication to make scalability possible. The advantage scalability provides is that it allows the user to customize the design for low and high power applications. In addition, the support for arbitrary precision allows the user to meet the desired security level. The third design utilizes the Montgomery Multiplication algorithm to develop an unified architecture that can perform a modular multiplication for GF(p) and GF(2^k) and a polynomial multiplication for NTRU. The unified design only requires an additional 10 gates in order for the Montgomery Multiplier core to compute the polynomial multiplication for NTRU. However, this added support for NTRU presents some restrictions on the supported lengths of the moduli and on the chosen value for the residue for the GF(p) and GF(2^k) cases. Despite these restrictions, this unified architecture is now capable of supporting public key operations for the majority of Public-Key Cryptosystems.

Abstract not available

In this thesis, we present a novel, elegant and simple method for secure transaction authentication and non-repudiation for trading multimedia content. Multimedia content can be video, images, text documents, music, or any form of digital signal, however here we will focus particular on still images with application to video. We will provide proof that not only can receiving parties within a transaction be untrustworthy, but the owner, or members within an owning party, also cannot be trusted. Known as the insider attack, this attack is particularly prevalent in multimedia transactions. Thus the focus of the thesis is on the prevention of piracy, with particular emphasis on the case where the owner of a document is assumed to be capable of deceit, placing the system under the assumption of mutual distrust. We will introduce a concept called staining, which will be used to achieve authentication and non-repudiation. Staining is composed of two key components: (1) public-key cryptography; and (2) steganographic watermarking. The idea is to watermark a multimedia document after encryption, thereby introducing a stain on the watermark. This stain is due to the non-commutative nature of the scheme, so that decryption will be imperfect, leaving a residue of the cryptographic process upon the watermark. Essentially, secrets from the owner (the watermark) and the receiver (the cryptographic key) are entangled rather than shared, as in most schemes. We then demonstrate our method using image content and will test several different common cryptographic systems with a spread-spectrum type watermark. Watermarking and cryptography are not usually combined in such a manner, due to several issues such as the rigid nature of cryptography. Contrary to the expectation that there will be severe distortions caused to the original document, we show that such an entanglement is possible without destroying the document under protection. We will then attack the most promising combination of systems by introducing geometric distortions such as rotation and cropping, as well as compressing the marked document, to demonstrate that such a method is robust to typical attacks. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1297339 / Thesis (Ph.D.) - University of Adelaide, School of Electrical and Electronic Engineering, 2007

This thesis investigates applications of puncturing in error-correction coding and physical layer security with an emphasis on binary and non-binary LDPC codes. Theoretical framework for the analysis of punctured binary LDPC codes at short block lengths is developed and a novel decoding scheme is designed that achieves considerably faster convergence than conventional approaches. Subsequently, optimized puncturing and shortening is studied for non-binary LDPC codes over binary input channels. Framework for the analysis of punctured/shortened non-binary LDPC codes over the BEC channel is developed, which enables the optimization of puncturing and shortening patterns. Insight from this analysis is used to develop algorithms for puncturing and shortening of non-binary LDPC codes at finite block lengths that perform well. It is confirmed that symbol-wise puncturing is generally bad and that bit-wise punctured non-binary LDPC codes can significantly outperform their binary counterparts, thus making them an attractive solution for future communication systems; both for error-correction and distributed compression. Puncturing is also considered in the context of physical layer security. It is shown that puncturing can be used effectively for coding over the wiretap channel to hide the message bits from eavesdroppers. Further, it is shown how puncturing patterns can be optimized for enhanced secrecy. Asymptotic analysis confirms that eavesdroppers are forced to operate at BERs very close to 0.5, even if their signal is only slightly worse than that of the legitimate receivers. The proposed coding scheme is naturally applicable at finite block lengths and allows for efficient, almost-linear time encoding. Finally, it is shown how error-correcting codes can be used to solve an open problem of compressing data encrypted with block ciphers such as AES. Coding schemes for multiple chaining modes are proposed and it is verified that considerable compression gains are attainable for binary sources.

Thesis (Ph.D.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references (leaf 130-140) and index.

Από τότε που ολοένα και περισσότερα εμπιστευτικά δεδομένα ανταλλάσσονται με ηλεκτρονικό τρόπο η ανάγκη για προστασία των δεδομένων αυτών γίνεται ολοένα και μεγαλύτερη. Στις πραγματικές εφαρμογές όπου χρησιμοποιούνται συστήματα κρυπτογραφίας παρατηρούνται νέες τεχνικές επίθεσης πέρα από αυτές που στηρίζονται στην μαθηματική ανάλυση. Εφαρμογές τόσο σε υλικό όσο και σε λογισμικό, παρουσιάζουν ένα αχανές πεδίο από επιθέσεις. Οι Side-Channel-Attacks εκμεταλλεύονται πληροφορίες που διαρρέουν από μια συσκευή κρυπτογράφησης. Μάλιστα από την μέρα που εμφανίστηκε μία συγκεκριμένη μέθοδος επίθεσης, προσελκύει ολοένα και μεγαλύτερο ενδιαφέρον. Πρόκειται για την Διαφορική Ανάλυση Ισχύος (Differential Power Analysis (DPA)) που πρωτοπαρουσιάστηκε από την Cryptography Research. Η DPA χρησιμοποιεί την πληροφορία που διαρρέει από μια συσκευή κρυπτογράφησης, και πρόκειται για την κατανάλωση ισχύος. Μία λιγότερο δυνατή παραλλαγή της DPA είναι η Simple Power Analysis (SPA), που παρουσιάστηκε επίσης από την Cryptography Research. Βασικός στόχος της DPA είναι να μετρηθεί με ακρίβεια η κατανάλωση ισχύος του συστήματος. Έπειτα απαιτείται η γνώση του αλγόριθμου που εκτελείται από την συσκευή, ενώ τέλος απαραίτητο είναι ένα σύνολο από γνωστά κρυπτογραφήματα ή αυθεντικά μηνύματα. Η στρατηγική της επίθεσης απαιτεί την μέτρηση πολλών δειγμάτων και στην συνέχεια την διαίρεσή τους σε δύο ή περισσότερα σύνολα με βάση ενός κανόνα . Εν συνεχεία στατιστικές μέθοδοι χρησιμοποιούνται για την επιβεβαίωση του κανόνα αυτού. Αν και μόνο αν ο κανόνας αυτός είναι σωστός τότε μπορούμε να παρατηρήσουμε αξιοπρόσεκτες τιμές στην στατιστική ανάλυση. Σκοπός της εργασίας αυτής είναι να καθορίσουμε με περισσότερες λεπτομέρειες την DPA, να αναπτύξουμε ένα περιβάλλον που θα πραγματοποιεί την επίθεση αυτή, σε μια υλοποίηση του DES (Data Encryption Standard) αλγόριθμου κρυπτογράφησης με την χρήση FPGA Board και να γίνει πειραματική εκτίμηση. / -

This thesis explores architectural level optimizations to make secure systems more efficient, secure and affordable. It extends prior work for secure architecture in several areas. It proposes a new combined memory encryption and authentication scheme which uses very small on-chip storage area and incurs much less performance overhead compared with prior work. In addition, the thesis studies the issues of applying architectural support for data security to distributed shared memory systems. It presents a scheme which is scalable with large-scale systems and only introduces negligible performance overhead for confidentiality and integrity protection. Furthermore, the thesis also investigates another source of reducing performance overhead in secure systems through optimizing on-chip caching schemes and minimizing off-chip communications.

Title from screen page; viewed 10 Oct 2005. / Thesis (PhD)--Macquarie University, Division of Information and Communication Sciences, Dept. of Computing, 2004. / Bibliography: leaves 163-175. / Introduction -- Cryptographic essentials -- Multicast: structure and security -- Authentication of multicast streams -- Authentication of concast communication -- Authentication of transit flows -- One-time signatures for authenticating group communication -- Authentication of anycast communication -- Authentication of joining operation - Conclusion and future directions. / Electronic publication; full text available in PDF format. / Multicast is a relatively new and emerging communication mode in which a sender sends a message to a group of recipients in just one connection establishment... reducing broadband overhead and increasing resource utilization in the already congested and contented network... The focus of the research in this area has been in two directions: first, building an efficient routing infrastructure, and secondly, building a sophisticated security infrastructure. The focus of this work is on the second issue. / An ideal authenticated multicast environment ... provides authenticity for all the communication operations in the system... We ... propose a comprehensive solution to the problem ... for all its possible operations... 1. one-to-one (or joining mode) 2. one-to-many (or broadcast mode) 3. many-to-one (or concast mode) 4. intermediate (or transit mode) ... We study the ... mode known as anycast, in which a server is selected from a group of servers. Further we develop ... schemes for group-based communication exploiting the distinct features of one-time signatures... cover situations when a threshold number of participants are involved and ... where a proxy signer is required. / Electronic reproduction. / Mode of access: World Wide Web. / Also available in a print form

Thesis (M.Comp.Sc.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: leaf 66-72.

Thesis (M.Comp.Sc.)--University of Wollongong, 2005. / Typescript. This thesis is subject to a 6 month embargo (12/12/05 to 12/06/06) and may only be viewed and copied with the permission of the author. For further information please Contact the Archivist. Includes bibliographical references: leaf 65-72.