Abhishek Parakh

Online data storage using implicit security

It is advantageous to use implicit security for online data storage in a cloud computing environment. We describe the use of a data partitioning scheme for implementing such security involving the roots of a polynomial in finite field. The partitions are stored on randomly chosen servers on the network and they need to be retrieved to recreate the original data. Data reconstruction requires access to each server, login password and the knowledge of the servers on which the partitions are stored. This scheme may also be used for data security in sensor networks and internet voting protocols.

Space efficient secret sharing for implicit data security

This paper presents a k-threshold computational secret sharing technique that distributes a secret S into shares of size |S|k-1, where |S| denotes the secret size. This bound is close to the space optimal bound of |S|k if the secret is to be recovered from k shares. In other words, our technique can be looked upon as a new information dispersal scheme that provides near optimal space efficiency. The proposed scheme makes use of repeated polynomial interpolation and has potential applications in secure information dispersal on the Web and in sensor networks.

A probabilistic quantum key transfer protocol

We propose a protocol to transfer a one-time pad (in a probabilistic manner) from Alice to Bob, over a public channel. The proposed protocol is unique because Bob merely acts as a receiver of the pad (secret key); that is, Bob does not need to send any message back to Alice unless he detects eavesdropping. Such a secure transfer of one-time pad, over public channel, is not possible in classical cryptography, and in quantum cryptography, all previous protocols require Bob to send almost as many messages back to Alice as she does to Bob to establish a key. Copyright

Oblivious Transfer Using Elliptic Curves

We introduce the idea of oblivious transfer to elliptic curve cryptography (ECC), which has the advantage of providing same security with a 160-bit key compared to 1024-bit key needed by RSA. Oblivious transfer forms the basis of numerous protocols which can all now be analogously developed in ECC using the algorithm we present in this paper. Also, we look into one of its important applications known as chosen one-out-of-two oblivious transfer and present a protocol for it using the algorithm we discuss

A Tree Based Recursive Information Hiding Scheme

This paper presents a k-out-of-n recursive information hiding scheme based on an n-ary tree data structure. In recursive hiding of information, the user encodes additional information in the shares of the secret, intended to be originally shared, without an expansion in the size of the latter. The proposed scheme has applications in secure distributed storage and information dispersal protocols. It may be used as a steganographic channel to transmit hidden information, which may be used for authentication and verification of shares and the reconstructed secret itself.

Recursive secret sharing for distributed storage and information hiding

This paper presents a recursive computational multi-secret sharing technique that hides k − 2 secrets of size b each into n shares of a single secret S of size b, such that any k of the n shares suffice to recreate the secret S as well as all the hidden secrets. This may act as a steganographic channel to transmit hidden information or used for authentication and verification of shares and the secret itself. Further, such a recursive technique may be used as a computational secret sharing technique that has potential applications in secure and reliable storage of information on the Web, in sensor networks and information dispersal schemes. The presented technique, unlike previous computational techniques, does not require the use of any encryption key or storage of public information.

An Efficient Quasigroup Block Cipher

Low powered devices, such as smart phones, tablets and sensors, present a particular challenge for advanced encryption systems. In this paper, we present a new quasigroup block encryption system that has low memory and computational requirements and hence suitable for low powered devices. We compare its performance against Advanced Encryption Standard-256 (AES-256) bit algorithm using the NIST statistical test suite (NIST-STS). Since it is well known that a good encryption algorithm must destroy any statistical properties of the input sequence and produce output close to a true random sequence, the NIST-STS suite results provide us a good test bench. In almost all tests from the suite, the proposed algorithm performs better than AES-256.

Matrix based key agreement algorithms for sensor networks

Communication between nodes in a sensor network is often secured by the use of symmetric keys installed on them before deployment. A more efficient method is to install sensors with a small amount of secret information that can be used to generate a pairwise common key when required. We propose new key agreement algorithms based on matrix factorization that requires a maximum of μ multiplications to generate a key, where M ≥ N is a system parameter and N is the total number of nodes in the network.

Efficient key management in sensor networks

We present an efficient key distribution scheme for sensor networks in which resource constraints and the possibility of node capture and malfunctions are considered. We deal with the problem of efficient routing and key distribution simultaneously. The resulting scheme is scalable and resilient to node captures and malfunctions. Under certain assumptions, the scheme has an upper bound of log2N on the diameter of the network and the number of keys required per node (where N is the number of nodes in the network).

Oblivious Transfer Based on Key Exchange

Abstract Key-exchange protocols have been overlooked as a possible means for implementing oblivious transfer (OT). In this article, we present protocols for mutual exchange of secrets, 1-out-of-2 OT and coin-flipping similar to the Diffie-Hellman protocol using the idea of obliviously exchanging encryption keys. Since the Diffie-Hellman scheme is widely used, our protocol may provide a useful alternative to the conventional methods for implementation of oblivious transfer and a useful primitive in building larger cryptographic schemes.