Bimal K. Roy

Progress in Cryptology —INDOCRYPT 2000

The correlation of a Boolean function with its variables is closely related to the correlation attack on stream cipher. The Walsh transformation is the main tool to study the correlation of Boolean functions. The Walsh transformation of a Boolean function with r variables has 2 coefficients. Let k denote the number of non–zero coefficients of the Walsh Transformations. The paper studies the functions with 1 ≤ k ≤ 8. It is proved that the functions with k = 1 are the linear functions only, there are no functions with k = 2, 3, 5, 6, 7, and finally we construct all functions with k = 4 or 8. keywords: Boolean function, correlation, Walsh transformation, stream cipher

A key pre-distribution scheme for wireless sensor networks: merging blocks in combinatorial design

In this paper, combinatorial design followed by randomized merging strategy is applied to key pre-distribution in sensor nodes. A transversal design is used to construct a (v, b, r, k) configuration and then randomly selected blocks are merged to form the sensor nodes. We present detailed mathematical analysis of the number of nodes, number of keys per node and the probability that a link gets affected if certain number of nodes are compromised. The technique is tunable to user requirements and it also compares favourably with state of the art design strategies. An important feature of our design is the presence of more number of common keys between any two nodes. Further, we study the situation when properly chosen blocks are merged to form sensor nodes such that the number of intra-node common key is minimized. We present a basic heuristic for this approach and show that it provides slight improvement in terms of certain parameters than our basic random merging strategy.

Progress in Cryptology - INDOCRYPT 2009

Post-Quantum Cryptology.- Secure Parameters for SWIFFT.- FSBday.- Key Agreement Protocols.- Reusing Static Keys in Key Agreement Protocols.- A Study of Two-Party Certificateless Authenticated Key-Agreement Protocols.- Side Channel Attacks.- Fault Analysis of Rabbit: Toward a Secret Key Leakage.- On Physical Obfuscation of Cryptographic Algorithms.- Cache Timing Attacks on Clefia.- Symmetric Cryptology.- Software Oriented Stream Ciphers Based upon FCSRs in Diversified Mode.- On the Symmetric Negabent Boolean Functions.- Improved Meet-in-the-Middle Attacks on AES.- Hash Functions.- Related-Key Rectangle Attack of the Full HAS-160 Encryption Mode.- Second Preimage Attack on SHAMATA-512.- Towards Secure and Practical MACs for Body Sensor Networks.- Indifferentiability Characterization of Hash Functions and Optimal Bounds of Popular Domain Extensions.- A Distinguisher for the Compression Function of SIMD-512.- Number Theoretic Cryptology.- Sampling from Signed Quadratic Residues: RSA Group Is Pseudofree.- Software Implementation of Pairing-Based Cryptography on Sensor Networks Using the MSP430 Microcontroller.- A New Hard-Core Predicate of Pailliers Trapdoor Function.- Lightweight Cryptology.- Private Interrogation of Devices via Identification Codes.- RFID Distance Bounding Multistate Enhancement.- Two Attacks against the F f RFID Protocol.- Signature Protocols.- Efficient Constructions of Signcryption Schemes and Signcryption Composability.- On Generic Constructions of Designated Confirmer Signatures.- Verifiably Encrypted Signatures from RSA without NIZKs.- Identity Based Aggregate Signcryption Schemes.- Multiparty Computation.- Round Efficient Unconditionally Secure MPC and Multiparty Set Intersection with Optimal Resilience.- Non-committing Encryptions Based on Oblivious Naor-Pinkas Cryptosystems.- Oblivious Multi-variate Polynomial Evaluation.

Key pre-distribution using partially balanced designs in wireless sensor networks

We propose two deterministic key predistribution schemes in a wireless sensor network (WSN), in which sensor nodes are deployed randomly. Both the schemes are based on combinatorial designs, called partially balanced incomplete block designs (PBIBD). An important feature of our scheme is that every pair of nodes within communication range can communicate directly, making communication faster and efficient. The number of keys per node is of the order of

Key predistribution using combinatorial designs for grid-group deployment scheme in wireless sensor networks

\sqrt N

Key predistribution using partially balanced designs in wireless sensor networks

, where

Key Predistribution Schemes Using Codes in Wireless Sensor Networks

N

Combinatorial batch codes: A lower bound and optimal constructions

is the number of nodes in the network. Our second design has the added advantage that we can introduce new nodes in the network keeping the key pool fixed. This makes the network scalable. We study the resiliency of the network under node compromise and show that our designs give better results than the existing ones.

A new black and white visual cryptographic scheme for general access structures

We propose a new grid-group deployment scheme in wireless sensor networks. We use combinatorial designs for key predistribution in sensor nodes. The deployment region is divided into square regions. The predistribution scheme has the advantage that all nodes within a particular region can communicate with each other directly and nodes which lie in a different regions can communicate via special nodes called agents which have more resources than the general nodes. The number of agents in a region is always three, whatever the size of the network. We give measures of resiliency taking the Lee distance into account. Apart from considering the resiliency in terms of fraction of links broken, we also consider the resiliency as the number of nodes and regions disconnected when some sensor are compromised. This second measure, though very important, had not been studied so far in key predistribution schemes which use deployment knowledge. We find that the resiliency as the fraction of links compromised is better than existing schemes. The number of keys preloaded in each sensor node is much less than all existing schemes and nodes are either directly connected or connected via two hop paths. The deterministic key predistribution schemes result in constant-time computation overhead for shared key discovery and path key establishment.

Application of least squares method in matrix form: simultaneous determination of ibuprofen and paracetamol in tablets

We propose two deterministic key predistribution schemes in a Wireless Sensor Network (WSN), in which sensor nodes are deployed randomly. Both the schemes are based on Partially Balanced Incomplete Block Designs (PBIBD). An important feature of our scheme is that every pair of nodes can communicate directly, making communication faster and efficient. The number of keys per node is of the order of √N, where N is the number of nodes in the network. Our second design has the added advantage that we can introduce new nodes in the network keeping the key pool fixed. We study the resiliency of the network under node compromise and show that our designs give better results than the existing ones.