Arpita Maitra

Eavesdropping in semiquantum key distribution protocol

Abstract In semiquantum key-distribution (Boyer et al.) Alice has the same capability as in BB84 protocol, but Bob can measure and prepare qubits only in { | 0 〉 , | 1 〉 } basis and reflect any other qubit. We study an eavesdropping strategy on this scheme that listens to the channel in both the directions. With the same level of disturbance induced in the channel, Eve can extract more information using our two-way strategy than what can be obtained by the direct application of one-way eavesdropping in BB84.

A Resilient Quantum Secret Sharing Scheme

A resilient secret sharing scheme is supposed to generate the secret correctly even after some shares are damaged. In this paper, we show how quantum error correcting codes can be exploited to design a resilient quantum secret sharing scheme, where a quantum state is shared among more than one parties.

Efficient quantum algorithms to construct arbitrary Dicke states

In this paper, we study several quantum algorithms toward the efficient construction of arbitrary arbitrary Dicke state. The proposed algorithms use proper symmetric Boolean functions that involve manipulation with Krawtchouk polynomials. Deutsch–Jozsa algorithm, Grover algorithm, and the parity measurement technique are stitched together to devise the complete algorithm. In addition to that we explore how the biased Hadamard transformation can be utilized into our strategy, motivated by the work of Childs et al. (Quantum Inf Comput 2(3):181–191, 2002).

Another Look at Symmetric Incoherent Optimal Eavesdropping against BB84

The BB84 protocol is used by Alice (the sender) and Bob (the receiver) to settle on a secret classical bit-string by communicating qubits over an insecure quantum channel where Eve (the Eavesdropper) can have access. In this paper, we revisit a well known eavesdropping technique against BB84. We claim that there exist certain gaps in understanding the existing eavesdropping strategy in terms of cryptanalytic view and we try to bridge those gaps in this paper.

On Universality of Quantum Fourier Transform

A methodology is presented to obtain the basis of qudits which are admissible to quantum Fourier transform (QFT) in the sense that the set of such kets are related by the QFT in the same way as the kets of the computational basis. We first study this method for qubits to characterize the ensemble that works for the Hadamard transformation (QFT for two dimension). In this regard we identify certain incompleteness in the result of Maitra and Parashar (Int. J. Quantum Inform. 4 (2006) 653). Next we characterize the ensemble of qutrits for which QFT is possible. Further, some theoretical results related to higher dimensions are also discussed. Considering the unitary matrix Un related to QFT, the issue boils down to the problem of characterizing matrices that commute with Un.

Collaborative Information Service - Privacy Algebra for User Defined Security

With the increased activity over the internet and globalization of the market economy collaborative computing becomes an important area of research. Security is an increasing concern because of chances of malicious elements breaching the network of collaborating partners. Further the level of mutual belief among the collaborators would not be identical and may change with experience. Thus the concept of user defined flexible security requirements arose. The idea of user defined privacy template was brought in IRaaS (Information Retrieval as a Service) (Pal and Bose 2013) which is a flexible system of information services to customers who seek information from various sources through a service provider. The idea was further extended to CIS (Collaborative Information Service) (Pal and Bose 2016) which provides a framework for general information exchange activities (not restricted to retrievals only) for a set of collaborating partners. The current work extends CIS by introducing privacy algebra to be applied on templates to get a concise expression of privacy restrictions. CIS is a step towards a privacy aware collaborative computing problem.