V. Ch. Venkaiah

Multi-Stage Multi-Secret Sharing Schemes Based on Chinese Remainder Theorem

One secret sharing scheme that uses the Mignottes sequence and another secret sharing scheme that uses the Asmuth-Bloom sequence are proposed in this paper. Both the secret sharing schemes are based on the Chinese Remainder Theorem (CRT). Novelty of the two proposed schemes is that the shares of the participants are reusable i.e. same shares are applicable even with a new secret. Also only one share needs to be kept by each participant even for the muslti-secret sharing scheme. Further, the schemes are capable of verifying the honesty of the participants including the dealer. Correctness of the proposed schemes is discussed and show that the proposed schemes are computationally secure.

Computationally perfect compartmented secret sharing schemes based on MDS codes

Two compartmented secret sharing schemes are proposed in this paper. Constructions of the proposed schemes are based on the maximum distance separable (MDS) codes. One of the proposed schemes is perfect in classical sense and the other scheme, what we call, is computationally perfect. By computationally perfect, we mean, an authorised set can always reconstruct the secret in polynomial time whereas for an unauthorised set this is computationally hard. This is in contrast to some of the existing schemes in the literature, in which an authorised set can recover the secret only with certain probability. Also, in our schemes unlike in some of the existing schemes, the size of the ground field need not be extremely large. One of the proposed schemes is shown to be ideal and the information rate for the other scheme is 1/2. Both the schemes are efficient and require O ( mn 3 ), where n is the number of participants and m is the number of compartments.

Computationally Perfect Secret Sharing Scheme Based on Error-Correcting Codes

In this paper, we propose a secret sharing scheme for compartmented access structure with lower bounds. Construction of the scheme is based on the Maximum Distance Separable (MDS) codes. The proposed scheme is ideal and computationally perfect. By computationally perfect, we mean, an authorized set can always reconstruct the secret in polynomial time whereas for an unauthorized set this is computationally hard. This is in contrast to some of the existing schemes in the literature, in which an authorized set can recover the secret only with certain probability. Also, in our scheme unlike in some of the existing schemes, the size of the ground field need not be extremely large. This scheme is efficient and requires O(mn 3), where n is the number of participants and m is the number of compartments.

Sequential secret sharing scheme based on Chinese remainder theorem

Multilevel Sequential secret sharing scheme is a composition of multilevel threshold secret sharing and multi-stage multi-secrets sharing scheme. In this scheme, shareholders are partitioned into multiple subsets. Each subset will have multi-secrets. Shareholders in each subset could reconstruct many secrets in the consecutive stage if t or more number of shares are available. In addition, a lower level subset can use higher level subset shares to reconstruct the secret. Verification is provided to detect cheating in the proposed scheme. This scheme is unconditionally secure and it is efficient.

Sequential Secret Sharing Scheme Based on Level Ordered Access Structure

In Software Industry an application can be released to production only after it has gone through Unit testing, followed by Integration testing, then System testing and finally Acceptance testing. Note here that without the completion of unit testing, integration testing cannot be started and similarly without the completion of integration testing, system testing cannot be started and so on. That is the ordering is important. To realize this or similar kind of activity we need a hierarchial access structure that has in built ordering among the levels. Existing access structures fail to realize this scenario as they are short of enforcing the required ordering. The purpose of this pa- per is to propose an access structure that caters to this kind of scenarios and come up with schemes that realize this access structure. We call this new access structure as Level Ordered Access Structure (LOAS) and the schemes that realize this access structure as Level Ordered Secret Sharing (LOSS) schemes.

New secret sharing scheme for multipartite access structures with threshold changeability

A secret sharing method that realizes a variation of the multipartite access structure is proposed in this paper. The method indirectly distributes shares of the main secret with one random secret among a set of players. Again the shares of some unknown random secrets are calculated by the players and shared among themselves. At each level, the players can change their threshold to any arbitrary value dynamically. Each subset of the players can only recover the secret corresponding to their own level. The main secret will be retrieved by any level players if and only if all the secrets in other levels are first recovered. The access structure that our scheme realizes is such that the players of different levels calculate secrets individually but to recover the main secret cooperation of players from all the levels are required.

Node Authentication Using BLS Signature in Distributed PKI Based MANETs

Authenticating a node in mobile ad-hoc networks is a challenging task due to their dynamic and resource constraint infrastructure. For this purpose, MANETS adopt two kinds of approaches Public key cryptography and identity-based cryptography. In Public Key Infrastructure (PKI), Certificate Authority (CA) is responsible for key management. In order to adapt it to MANET, the job of the CA must be distributed. The master secret key is shared among the nodes of the MANET, to self-organize the network without a central authority.The key is shared based on Shamir secret sharing scheme with bivariate polynomial to make the MANET fully self-managed by nodes.In this paper, we considered PKI based scenario and proposed a new scheme to authenticate a node using BLS signature which is light weight compared to the existing schemes thus making it suitable for MANET.

Ideal and Computationally Perfect Secret Sharing Schemes for Generalized Access Structures

A secret sharing scheme is proposed in this paper. The scheme is ideal and uses computationally perfect concept. It uses a one way function and realizes generalized access structure. The scheme is useful for non-ideal access structures. For example, Stinson [14] has identified eighteen possible non-isomorphic monotone access structures with four participants. Fourteen of them admit ideal and perfect secret sharing schemes. The remaining four cannot be made both perfect and ideal. By making use of the computationally perfect concept, we propose ideal scheme for those four access structures.

Lightweight Cryptography for Distributed PKI Based MANETS

Because of lack of infrastructure and Central Authority(CA), secure communication is a challenging job in MANETs. A lightweight security solution is needed in MANET to balance its nodes resource tightness and mobility feature. The role of CA should be decentralized in MANET because the network is managed by the nodes themselves without any fixed infrastructure and centralized authority. In this paper, we created a distributed Public Key Infrastructure (PKI) using Shamir secret sharing mechanism which allows the nodes of the MANET to have a share of its private key. The traditional PKI protocols require centralized authority and heavy computing power to manage public and private keys, thus making them not suitable for MANETs. To establish a secure communication for the MANET nodes, we proposed a lightweight crypto protocol which requires limited resources, making it suitable for MANETs.

On the Construction and Performance of LDPC Codes

Low-Density-Parity-Check (LDPC) codes are excellent error correcting codes performing very close to the Shannon’s limit, enabling efficient and reliable communication. Ever since their importance was known, a lot of research has gone into the construction/designing of efficient LDPC codes. Many different construction methods have been proposed so far. This paper explores some of these construction methods and includes their performance results on the Additive White Gaussian Noise (AWGN) channel. In particular, LDPC code construction using cage graphs and permutation matrices are investigated. Irregular LDPC codes have been constructed from regular LDPC codes using an expansion method, followed by their code rate comparison.