Revisiting Dedicated and Block Cipher based Hash Functions

A hash function maps a variable length input into a fixed length output. The hash functions that are used in the information security related applications are referred as cryptographic hash functions. Hash functions are being used as building blocks of many complex cryptographic mechanisms and protocols. Construction of a hash function consists of two components. First component is a compression function and the second component is a domain extender. The various hash function design philosophies try to design the compression function from different angles. Two major categories of hash functions are: dedicated hash functions, and block cipher-based hash functions. These two kinds of design philosophies have been revisited in this paper. Two dedicated has functions from MD4 family - MD4, and SHA-256 constructions have been detailed in this paper. To limit the scope of this paper in this framework, discussions on attacks on hash functions, and SHA-3 finalists have been excluded here. Keywords

Deterministic Merging of Blocks in Combinatorial Design based Key Predistribution in Distributed Wireless Sensor Network

Sensor nodes have severe constraints in terms of its resources such as processing power, memory, communication range, battery power. Due to wireless nature of communication between nodes in a wireless sensor network, any attacker can intercept the communicating messages between sensor nodes. So the need for securing these messages is obvious. Due to resource constraints of sensor nodes, public key cryptography can’t be employed for securing the communication as public key cryptography demands much computational effort. So, private key cryptography is natural choice for securing the communication in wireless sensor network. Key predistribution has become obvious choice for distributing keys in sensor nodes for secured communication in a wireless sensor network. A pool of keys is first taken, and then a set of keys from this key pool is installed in every sensor node before their deployment. The keys predistributed to a particular sensor node can be drawn from the key pool probabilistically or deterministically. Combinatorial design which was originated as a branch of statistics and later found its vast application in coding theory and of late in cryptography plays a vital role in deterministic key predistribution. The connectivity and resiliency offered by some combinatorial design based key predistribution schemes can be sometimes offered by merging of blocks and then assign these merged blocks to sensor nodes. The question is how to choose blocks for merging? There is a prior general work on merging of blocks which has been studied on transversal design based key predistribution scheme. This approach is not deterministic, but heuristic. A deterministic algorithm for merging of blocks has been proposed. The orthogonal array based key predistribution scheme has been studied in detail and the non suitability of merging approach to improve its performance has been shown. In addition, a key establishment algorithm for transversal design based key predistribution scheme has been proposed

Key Predistribution Schemes in Distributed Wireless Sensor Network using Combinatorial Designs Revisited

A Sensor Node in Wireless Sensor Network has very limited resources such as processing capability, memory capacity, battery power, and communication capability. When the communication between any two sensor nodes are required to be secured, the symmetric key cryptography technique is used for its advantage over public key cryptography in terms of requirement of less resources. Keys are pre-distributed to each sensor node from a set of keys called key pool before deployment of sensors nodes. Combinatorial design helps in a great way to determine the way keys are drawn from the key pool for distributing to individual sensor nodes. We study various deterministic key predistribution techniques that are based on combinatorial design

A Deterministic Approach of Merging of Blocks in Transversal Design based Key Predistribution

Transversal Design is a well known combinatorial design that has been used in deterministic key predistribution scheme. Merging of blocks in a design sometimes helps to obtain a key predistribution scheme with better performance. A deterministic merging strategy to merge the blocks has been discussed. Also, a simple key establishment method for transversal design based key predistribution scheme has been discussed

Weakness of Key Predistribution Scheme Proposed by J. Dong et al.

A Sensor Node in Wireless Sensor Network has very limited resources such as processing capability, memory capacity, battery power, and communication capability. When the communication between any two sensor nodes are required to be secured, the symmetric key cryptography technique is used for its advantage over public key cryptography in terms of requirement of less resources. Keys are pre-distributed to each sensor node from a set of keys called key pool before deployment of sensors nodes. Combinatorial design helps in a great way to determine the way keys are drawn from the key pool for distributing to individual sensor nodes. J. Dong et al proposed a key predistribution scheme based on orthogonal array. We present the weakness of this predistribution scheme

Characterization of nanodiamonds for metamaterial applications

Several different types of nanodiamonds were characterized in order to find the best sample to be used in further experiments with metamaterials. In this work we present the results of optical analysis of aqueous suspensions containing nanodiamonds, SEM analysis of diamond particles dispersed on silicon substrates and measurements of photoluminescence from defects in nanodiamonds