Mohammad Umar Siddiqi

Multiple error detection and correction based on redundant residue number systems

This paper presents some results on multiple error detection and correction based on the Redundant Residue Number System (RRNS). RRNS is often used in parallel processing environments because of its ability to increase the robustness of information passing between the processors. The proposed multiple error correction scheme utilizes the Chinese Remainder Theorem(CRT) together with a novel algorithm that significantly simplifies the error correcting process for integers. An extension of the scheme further reduces the computational complexity without compromising its error correcting capability. Proofs and examples are provided for the coding technique.

Cryptanalysis of two anonymous buyer-seller watermarking protocols and an improvement for true anonymity

By combining techniques of watermarking and fingerprinting, a sound buyer-seller watermarking protocol can address the issue of copyright protection in e-commerce. In this paper, we analyze the security of two recent anonymous buyer-seller watermarking protocols proposed by Ju et. al and Choi et. al respectively, and prove that they do not provide the features and security as claimed. In particular, we show that i) the commutative cryptosystem used in Choi et. al’s protocol fails to prevent the watermark certification authority (WCA) from discovering the watermark (fingerprint) chosen by the buyer; ii) for both protocols, the seller can discover the watermark chosen by the buyer if he colludes with the WCA. Hence, these protocols cannot guard against conspiracy attacks. We further show that these protocols only provide “partial” anonymity, ie. the buyer’s anonymity is guaranteed only if WCA is honest. Our results suggest that the security of these protocols must assume the honesty of WCA, contrary to the designers’ original claim. Finally, we propose a new anonymous buyer-seller watermarking protocol which is more secure and efficient, and provides true anonymity.

Incremental Hash Function Based on Pair Chaining & Modular Arithmetic Combining

Most of the hash functions using iterative constructions, are inefficient for bulk hashing of documents with high similarity. In this paper, we present a new approach to construct a cryptographic hash function called Pair Chaining & Modular Arithmetic Combining Incremental Hash Function (PCIHF). PCIHF has some attractive properties, which are incrementality and parallelizability. The security of PCIHF has also been analyzed comprehensively. Finally, we show that PCIHF is not only universal one-way but also collision-free.

Multiresolution motion estimation for low-rate video frame interpolation

Interpolation of video frames with the purpose of increasing the frame rate requires the estimation of motion in the image so as to interpolate pixels along the path of the objects. In this paper, the specific challenges of low-rate video frame interpolation are illustrated by choosing one well-performing algorithm for high-frame-rate interpolation (Castango 1996) and applying it to low frame rates. The degradation of performance is illustrated by comparing the original algorithm, the algorithm adapted to low frame rate, and simple averaging. To overcome the particular challenges of low-frame-rate interpolation, two algorithms based on multiresolution motion estimation are developed and compared on objective and subjective basis and shown to provide an elegant solution to the specific challenges of low-frame-rate video interpolation.

A Framework for Describing Block Cipher Cryptanalysis

Block ciphers provide confidentiality by encrypting confidential messages into unintelligible form, which are irreversible without knowledge of the secret key used. During the design of a block cipher, its security against cryptanalysis must be considered. History has shown that a cipher designed without an adequate treatment of this would often lead to flaws and attacks by other researchers, sometimes devastatingly so. The problem for an aspiring cipher designer is that there are no standard texts on block cipher cryptanalysis because it is a fast changing field. The commonly available references are academic journals and conference proceedings, which may not be easy to grasp for researchers new to cryptanalysis. This paper presents the Xi framework, which is designed to compactly describe the block cipher cryptanalysis techniques regardless of their individual differences. This provides the cryptanalyst with a general framework to describe attacks on block ciphers, with the additional capabilities of allowing specification of the technical details of each different type of attack and of comparison of their respective strengths. Comparing different distinguishes in this framework also allows us to see natural generalizations and trigger nice open problems. We then show how to apply this Xi framework to the description of various attacks on popular and recent block ciphers

Haar Transformation of Linear Boolean Function

Haar transform is known to have the smallest computational requirement with a considerable interest and attraction drawn towards its spectral properties of Boolean functions. This paper presents Haar transform of Linear Boolean functions, where by the discussion is based on the transformation from the Boolean domain to the Haar domain. The resulting spectrum is given with the corresponding calculations presented, while the analysis of the respective spectral coefficients and their general properties being explored. Furthermore, the general formulation and/or equation derivation for the transformation is introduced.

Collision probability of one-to-many reversible mapping for IPv6 address generation

The paper presents results of collision probability evaluation of a one-to-many reversible mapping between user space and IPv6 address space which is developed to improve of IPv6 addresses generation in a local area network (LAN). Each time a user accesses the network, a dynamic unicast IPv6 address is given via DHCPv6 (Dynamic Host Configuration Protocol for IPv6) server to protect users from unwanted behavior analysis exploiting IPv6 addresses, thus protecting user privacy. This IPv6 address is generated dynamically using CFB (Cipher Feedback) mode of AES (Advanced Encryption Standard) algorithm based on user identity. The dynamic address can be uniquely linked to user if the need arises to allow network administrator to identify user based on captured IPv6 address during any security event. Checksum has been used for validation of probability of coincidental match of randomly generated Interface Id or generated by some other mechanism. The collision probability of the one-to-many reversible mapping for stateful IPv6 address assignment is evaluated using birthday paradox. The results show that the collision probability is very small indeed. The one-to-many reversible mechanism may be incorporated as an extension to the current DHCPv6 software.

Low rate video frame interpolation - challenges and solution

The challenges specific to interpolation at low video frame rates are illustrated by choosing an algorithm that performs well at high frame rates and applying it to low frame rates. The performance is illustrated by comparing the original algorithm, the algorithm adapted to low frame rate particularities, and simple averaging. To overcome the particular challenges of low frame rates, two algorithms were developed and compared on objective and subjective bases and shown to provide elegant solutions to the specific challenges of low frame rate video interpolation.

Computational complexity and implementation aspects of the incremental hash function

This paper gives the computational complexity and practical implementation aspects of a newly introduced incremental hash function called pair chaining & modular arithmetic combining incremental hash function (PCIHF). The boundary conditions of the parameters involved in the update process of PCIHF are examined in depth. It is proved that these basic requirements can be fulfilled easily. It is shown that in applications involving more than one update process if the number of blocks to be replaced is no more than 1/4 of the message blocks needed, the PCIHF is more efficient than standard SHA-1. Finally, it is observed that the computational complexity of combining operation is also important to ensure the practicability of PCIHF.

Generation of IPv6 Addresses Based on One-to-Many Reversible Mapping Using AES

The proliferation of enterprise wireless network raises the security concern in any organization despite the unarguable benefits it brings about. At the same time, the initiative to migrate from IPv4 (Internet Protocol version four) to IPv6 (Internet Protocol version six) is gaining momentum across the globe to resolve the IP address depletion problem as well as reaping the benefit of it. This research proposes a new scheme to manage IPv6 addresses in an enterprise wireless local area network (WLAN) which may be incorporated into DHCPv6 (Dynamic Host Configuration Protocol for IPv6) software. In this scheme each user is assigned a dynamic IPv6 address that is generated cryptographically. Each time a user tries to access the network, different IPv6 address will be given which is generated using CFB (Cipher Feedback) mode of AES (Advanced Encryption Standard) algorithm, whereby there is a one-to-many reversible mapping between user and IPv6 addresses. In this way, it is possible for the network administrator to identify users in real time from their IPv6 address although a user’s IP address regularly changed. Dynamically changing IP address will impede an external network adversary’s effort to track user’s online behavior, thus enhancing privacy.