Rosemary Koikara | Christ University, Bangalore, India (original) (raw)

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Papers by Rosemary Koikara

arXiv (Cornell University), Jul 5, 2024

대한전자공학회 학술대회, Nov 1, 2016

The Journal of Korean Institute of Communications and Information Sciences

Advanced Science Letters, 2016

Lecture Notes in Electrical Engineering, 2014

ABSTRACT Distributed Image Steganography (DIS) is a method of hiding secret information in multip... more ABSTRACT Distributed Image Steganography (DIS) is a method of hiding secret information in multiple carrier images, making it more difficult to trace than conventional steganographic techniques, and requiring a collection of affected images for the retrieval of the secret data. In this paper we concentrate on performing DIS on grayscale images using Block-DCT (Discrete Cosine Transformation). Distributed Image Steganography using Block-DCT adds to the security of DIS by embedding the secret data in the Frequency Domain. This makes the carrier images more immune to various steganalysis attacks as the secret data is more evenly distributed amongst the pixels of the carrier images making it more difficult to determine its existence. We use parity check in order to compensate for round-off errors that are typically associated with DCT.

Secret sharing is one of the branches of threshold cryptography. Secret sharing is intended to se... more Secret sharing is one of the branches of threshold cryptography. Secret sharing is intended to secure a secret key s among a group G with n participants. Thus, the secret key s can be reconstructed by collecting shares of t or more participants. Recently, the secret sharing concept has been applied in securing DNSsec root key. However, the idea of DNSsec root key security is based on Shamir’s (t, n)-secret sharing scheme and has implemented a smart card as a media to store the share information. To improve the system, we have considered Yang et al.’s scheme, one of the earlier practical secret sharing, to apply in DNSsec. By combining these two systems, we propose a biometrics-based practical secret sharing for DNSsec to resolve the problem with the storage media used. Also, we improve the drawbacks of Yang et al.’s scheme by producing a more efficient and asynchronous reconstruction phase compared to other secret sharing. Furthermore, it is applicable to the DNSsec system. Keywords...

A secret sharing scheme is a technique in which a dealer distributes shares of a secret to variou... more A secret sharing scheme is a technique in which a dealer distributes shares of a secret to various participants in such a way that only authorized subsets of the participants belonging to the appropriate access structures can reconstruct the secret. (k, n)-threshold secret sharing was first introduced by Shamir and Blakley separately in 1979. Apart from this, there are various threshold secret sharing schemes that differ in the types of access structures. In this paper, we propose a scheme for threshold secret sharing that uses three-dimensional cellular automata (3D-CA). The secret is considered to be one of the initial configurations of the 3D-CA. An update mechanism in conjunction with various rules is used to create transitions in the configurations of the 3D-CA. These configurations of the CA are the shares that are distributed among the participants. During the reconstruction of the secret, k consecutive shares are required to successfully reconstruct the secret. This scheme i...

(t, n)-threshold secret sharing was first introduced by Shamir and Blakley separately in 1979. Ap... more (t, n)-threshold secret sharing was first introduced by Shamir and Blakley separately in 1979. Apart from this, there are threshold secret sharing schemes which use the Chinese Remainder Theorem (CRT). The above mentioned are three of the most extensively researched tools used for designing a (t, n)-threshold secret sharing scheme. In this paper we propose a scheme for Multilevel Threshold Secret Image Sharing using the CRT. Multilevel Threshold Secret Sharing (MTSS) is a generalization of the classical secret sharing scheme. In MTSS various participants are classified into levels and the secret is reconstructed from the shares submitted by participants depending on the various levels. Every level has a separate threshold such that a higher level will have a threshold value smaller than that of the threshold of a lower level. Now, participants in each level can reconstruct the secret if the number of shares available is equal to or greater than the threshold of that level. Higher level shares may be used to reconstruct a secret along with lower level shares depending on certain rules. Here, we use Chinese remainder theorem based on Asmuth-Bloom's scheme to perform MTSS in which the secret is an image. The use of Asmuth-Bloom's SS makes this scheme unconditionally secure. Our proposed scheme is the first time the CRT is being used for multilevel threshold secret image sharing.

Cellular Automata (CA) is used in pseudo-random number generators (PRNG) to produce high-rate ran... more Cellular Automata (CA) is used in pseudo-random number generators (PRNG) to produce high-rate random numbers. The randomness of such numbers directly depends upon the CA rules and the number of neighbor cells. The two-dimensional (2D) CA has several limitations such as, finding the best CA rules, boundary cell problems, etc. To address the problems existing in the 2D CA, we propose a random number generator based on 3D cellular automata. The proposed generator is based on rule numbers 43, 85, 170, and 201, and incremental boundary conditions. The rules are randomly changed after each cycle depending on a clock bit mechanism. The output bits are then passed to the Diehard and ENT test suites to test its randomness [1]. The results reveal that the bit stream generated by the proposed scheme passes all the tests present in the test suites.

Advances in Information Security, Privacy, and Ethics, 2020

In secret sharing, a secret is distributed between various participants in a manner that an autho... more In secret sharing, a secret is distributed between various participants in a manner that an authorized group of participants in the appropriate access structures can recover this secret. However, a dealer might get corrupted by adversaries and may influence this secret sharing or the reconstruction process. Verifiable secret sharing (VSS) overcomes this issue by adding a verifiability protocol to the original secret sharing scheme. This chapter discusses a computationally secure publicly verifiable secret sharing scheme constructed using the three-dimensional cellular automata (3D CA). The initial configuration of the 3D CA is the secret. The following configurations are devised to be the shares distributed among the participants. Update mechanisms and various rules make it hard for an adversary to corrupt or duplicate a share. To make it even more efficient, the authors added a verifiability layer such that a dealer posts a public share and a private share to each shareholder. The NIST test suite has been used to calculate the randomness of the shares.

Advances in Intelligent Systems and Computing, 2015

The Gilgit manuscripts belong to fifth century A.D. and are oeuvre of texts which deal with Buddh... more The Gilgit manuscripts belong to fifth century A.D. and are oeuvre of texts which deal with Buddhist work. It is one of the oldest manuscripts in the world and is considered to be a milestone in the history of Buddhist works in India. It is a collection of both official and unofficial Buddhist works which are believed to have helped in the evolution of many literatures including Chinese, Japanese, and Sanskrit. Since this manuscript is almost seventeen centuries old it has not been able to fully decipher the text yet. It has been laminated by the National Archives of India which proves it is one of the most important literatures concerning India. In this paper, we perform character-based image segmentation on Gilgit manuscript in order to simplify and to better identify character in the image of the manuscript. The employed method gives an accuracy of nearly 87 %.

International Journal of Engineering Research and, 2015

In this paper we are concerned with securing a secret image in such a way that only the sender an... more In this paper we are concerned with securing a secret image in such a way that only the sender and receiver know that a secret has been hidden in an image. Data hiding techniques are generally used to carry out this task. In this paper a data hiding scheme in the frequency domain using block-DCT is proposed. The aim of this scheme is to improve the data hiding capacity while maintaining the quality of the stego image. We use block-DCT to transform the cover image into the frequency domain. The block-DCT gives extra security to the secret image as the embedding is done on the DCT transformed coefficients of the cover image and not directly onto the pixels of the cover image as is done with data hiding in the spatial domain. In the frequency domain we quantize the cover image before the embedding process is carried out. The proposed scheme uses base notation to perform the data hiding. This scheme improves the quality of stego image, the data hiding capacity and also, the secret image is completely reconstructed. Index terms-Data Hiding, steganography, frequency domain, block-DCT, information and data security. I.

Secret sharing schemes are being widely used to distribute a secret between various participants ... more Secret sharing schemes are being widely used to distribute a secret between various participants so that an authorized subset of participants belonging to appropriate access structures can reconstruct this secret. However, a dealer might get corrupted by adversaries and may influence this secret sharing or the reconstruction process. Verifiable secret sharing (VSS) overcomes this issue by adding a verifiability protocol to the original secret sharing scheme. This article proposes a computationally secure publicly verifiable secret sharing scheme based on the three‐dimensional cellular automata (3D‐CA). Unlike the more widely used linear secret sharing schemes or secret sharing scheme based on the Chinese remainder theorem, our proposed scheme performs the secret sharing using 3D‐CA. The secret is considered one of the initial configurations of the 3D‐CA, and the following configurations are devised to be the shares distributed among the participants. Update mechanisms and various ru...

Proceedings of the 1st International Conference on Communication and Computer Engineering, Nov 2, 2014

Distributed Image Steganography (DIS) is a method of hiding secret information in multiple carrie... more Distributed Image Steganography (DIS) is a method of hiding secret information in multiple carrier images, making it more difficult to trace than conventional steganographic techniques, and requiring a collection of affected images for the retrieval of the secret data. In this paper we concentrate on performing DIS on grayscale images using Block-DCT (Discrete Cosine Transformation). Distributed Image Steganography using Block-DCT adds to the security of DIS by embedding the secret data in the Frequency Domain. This makes the carrier images more immune to various steganalysis attacks as the secret data is more evenly distributed amongst the pixels of the carrier images making it more difficult to determine its existence. We use parity check in order to compensate for round-off errors that are typically associated with DCT.