Dissertation and Thesis
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Item Design, Analysis of Security and Cryptanalysis of Message Authentication Codes(Indian Statistical Institute, Kolkata, 2022-12) Talnikar, SupritaThis thesis is a compilation of various message authentication codes having beyond the birthday bound (BBB) security. Kicking off with preliminary development in chapter 1, it proceeds to introduce the nEHtM (nonce-based Enhanced Hash-then-Mask) MAC in chapter 2, which is BBB-secure when nonce misuse occurs, through the concept of faulty nonces. The construction is based on a single block cipher, used on the inputs after they undergo a domain-separation. Next, chapter 3 tackles the security and cryptanalysis of MAC constructions that use pseudorandom permutations as primitives by introducing the construction PDMMAC (Permutation-based Davies-Meyer MAC) and its variants. The work on obtaining pseudorandom functions from PRPs by [53] lead to our exploration of PRP-based MACs, and one of our constructions was inspired by the DWCDM of [62]. This was instrumental in the search for an inverse-free permutation-based MAC with a single instance of permutation. This is addressed in chapter 4 through the p-EDM (permutation-based Encrypted Davies-Meyer), which follows the trend of constructing n-bit to n-bit PRFs by summing smaller constructions such as the Even-Mansour and the Davies-Meyer, like the SoEM and SoKAC constructions of [53] and the PDMMAC and variant constructions of [47] before it. The BBB security is again tight. Two interesting treatments of the DbHtS construction [61] can be found in chapters 5 and 6. A permutation-based version, dubbed p-DbHtS (permutation- based Double-block Hash-then-Sum) is proven to possess BBB security and a matching attack provided. Finally, a block cipher-based version of the original construction is shown to have BBB security in the multi-user setting for underlying hash functions that are constructed without the use of block Ciphers. Furthermore, each chapter extends Patarin’s Mirror Theory to provide partial bounds for solutions to a system of affine bivariate equations and non-equations satisfying certain conditions.Item Analysis and Design of Quantum Secure Communication System(Indian Statistical Institute, Kolkata, 2022-08) Das, NayanaQuantum secure direct communication (QSDC) is an important branch of quantum cryptog- raphy, where one can transmit a secret message securely without encrypting it by a prior key. Quantum dialogue (QD) is a process of two way secure and simultaneous communication using a single channel and quantum conference (Q.Conf) is a process of securely exchanging messages between three or more parties, using quantum resources. Deterministic secure quan- tum communication (DSQC) is another class of quantum secure communication protocol, to transmit secret message without any shared key, where at-least one classical bit is required to decrypt the secret message. In the practical scenario, an adversary can apply detector-side- channel attacks to get some non-negligible amount of information about the secret message. Measurement-device-independent (MDI) quantum protocols can remove this kind of detector- side-channel attack, by introducing an untrusted third party (UTP), who performs all the measurements in the protocol with imperfect measurement devices. For secure communica- tion, identity authentication is always important as it prevents an eavesdropper to impersonate a legitimate party. The celebrated Clauser, Horne, Shimony, and Holt (CHSH) game model helps to perform the security analysis of many two-player quantum protocols. In this thesis, we perform analysis of several existing QSDC and QD protocols, and also design some new efficient protocols. We present new approaches of QSDC, QD and DSQC protocols with user authentication, some of them are MDI protocols. We analyze the security of a QSDC protocol, an MDI-QSDC protocol, and an MDI-QD protocol. We improve the previous protocols and propose some modifications of the above protocols. We also present a Q.Conf protocol by generalizing the previous MDI-QD protocol and using the algorithm of the Q.Conf protocol, we propose a quantum multi-party computation protocol to calculate the XOR value of multiple secret numbers. Next, we generalize the CHSH game, and we demonstrate how to distinguish between dimensions two and three for some special form of maximally entangled states using the generalized version of the CHSH game.Item Improving the efficiency of RLWE-based IPFE and its application on privacy-preserving biometrics(Indian Statistical Institute,Kolkata, 2021-07) Adhikary, SupriyaEncryption is a method with which one can securely share data over an insecure channel. The traditional public-key encryption follows an all-or-nothing approach where the receiver is either able to get the whole message using a key or nothing. In functional encryption (FE) it is possible to control the amount of information revealed to the receiver. The emerging use of cloud computing and a massive amount of collected data leaves us with a question of data privacy. For many applications, the regular notion of public-key encryption may be insufficient. For example, a hospital may want to share patients’ private healthcare data with researchers for analytics without disclosing patients’ private information. Functional Encryption can be very useful in such a scenario, where the authority(hospital) can provide a secret key skf to the researchers corresponding to a function f and the researcher can only get the evaluation f (x), so the researchers can compute on patients’ data without violating the privacy of the patients. The idea functional encryption was first introduced in terms of identity-based encryp- tion [6, 41], attribute-based encryption [38] and predicated encryption [22]. All of these extensions and their variants can be unified under the name Functional Encryption for an arbitrary function f . Inner Product Functional Encryption (IPFE) is one of the variants of FE. IPFE has been instantiated based on different assumptions like decisional Diffie- Hellman(DDH), learning with errors (LWE) assumptions [3, 4]. The first IPFE scheme based on RLWE assumption has recently been introduced by Mera et al. [29]. RLWE schemes tend to be efficient but the main bottlenecks in any RLWE scheme are Gaussian sampling and large polynomial multiplication. These are the reasons concerning performance loss in these schemes. Improvements are required to these operations for better performance. Our primary objective in this thesis is two fold (a) Improving the efficiency of RLWE-based IPFE [29]: One of the basic obser- vations that we can have here is that we can run most of the sections in the scheme parallelly without getting any changes in the result. We have used OpenMP to im- plement a multi-threaded implementation of the scheme. This allows this code to run parallelly on multiple cores simultaneously and improve the performance.Another aspect of performance optimization is AVX2 implementation. Intel Advanced Vector Extensions (AVX) is a vector processor for doing single instruction multiple data (SIMD) operations on Intel architecture CPUs. They were first supported by i Intel with the Haswell processor, which shipped in 2013. We propose a fast vectorized polynomial multiplication using intel AVX2. (b) Privacy preserving biometric authentication : We introduce an IPFE-based privacy-preserving biometric authentication protocol. We use the optimized IPFE library developed in this work. We then show the difference between using this IPFE- based protocol and a similar HE-based approach of the protocol.