References of "Damodaran, Aditya Shyam Shankar 50033262"      in Complete repository Arts & humanities   Archaeology   Art & art history   Classical & oriental studies   History   Languages & linguistics   Literature   Performing arts   Philosophy & ethics   Religion & theology   Multidisciplinary, general & others Business & economic sciences   Accounting & auditing   Production, distribution & supply chain management   Finance   General management & organizational theory   Human resources management   Management information systems   Marketing   Strategy & innovation   Quantitative methods in economics & management   General economics & history of economic thought   International economics   Macroeconomics & monetary economics   Microeconomics   Economic systems & public economics   Social economics   Special economic topics (health, labor, transportation…)   Multidisciplinary, general & others Engineering, computing & technology   Aerospace & aeronautics engineering   Architecture   Chemical engineering   Civil engineering   Computer science   Electrical & electronics engineering   Energy   Geological, petroleum & mining engineering   Materials science & engineering   Mechanical engineering   Multidisciplinary, general & others Human health sciences   Alternative medicine   Anesthesia & intensive care   Cardiovascular & respiratory systems   Dentistry & oral medicine   Dermatology   Endocrinology, metabolism & nutrition   Forensic medicine   Gastroenterology & hepatology   General & internal medicine   Geriatrics   Hematology   Immunology & infectious disease   Laboratory medicine & medical technology   Neurology   Oncology   Ophthalmology   Orthopedics, rehabilitation & sports medicine   Otolaryngology   Pediatrics   Pharmacy, pharmacology & toxicology   Psychiatry   Public health, health care sciences & services   Radiology, nuclear medicine & imaging   Reproductive medicine (gynecology, andrology, obstetrics)   Rheumatology   Surgery   Urology & nephrology   Multidisciplinary, general & others Law, criminology & political science   Civil law   Criminal law & procedure   Criminology   Economic & commercial law   European & international law   Judicial law   Metalaw, Roman law, history of law & comparative law   Political science, public administration & international relations   Public law   Social law   Tax law   Multidisciplinary, general & others Life sciences   Agriculture & agronomy   Anatomy (cytology, histology, embryology...) & physiology   Animal production & animal husbandry   Aquatic sciences & oceanology   Biochemistry, biophysics & molecular biology   Biotechnology   Entomology & pest control   Environmental sciences & ecology   Food science   Genetics & genetic processes   Microbiology   Phytobiology (plant sciences, forestry, mycology...)   Veterinary medicine & animal health   Zoology   Multidisciplinary, general & others Physical, chemical, mathematical & earth Sciences   Chemistry   Earth sciences & physical geography   Mathematics   Physics   Space science, astronomy & astrophysics   Multidisciplinary, general & others Social & behavioral sciences, psychology   Animal psychology, ethology & psychobiology   Anthropology   Communication & mass media   Education & instruction   Human geography & demography   Library & information sciences   Neurosciences & behavior   Regional & inter-regional studies   Social work & social policy   Sociology & social sciences   Social, industrial & organizational psychology   Theoretical & cognitive psychology   Treatment & clinical psychology   Multidisciplinary, general & others     Showing results 1 to 9 of 9 1 Protocols for Stateful Zero-KnowledgeDamodaran, Aditya Shyam Shankar Doctoral thesis (2022)Privacy preserving protocols typically involve the use of Zero Knowledge (ZK) proofs, which allow a prover to prove that a certain statement holds true, to a verifier, without revealing the witness ... [more ▼]Privacy preserving protocols typically involve the use of Zero Knowledge (ZK) proofs, which allow a prover to prove that a certain statement holds true, to a verifier, without revealing the witness (secret information that allows one to verify whether said statement holds true) to the verifier. This mechanism allows for the participation of users in such protocols whilst preserving the privacy of sensitive personal information. In some protocols, the need arises for the reuse of the information (or witnesses) used in a proof. In other words, the witnesses used in a proof must be related to those used in previous proofs. We propose Stateful Zero Knowledge (SZK) data structures, which are primitives that allow a user to store state information related to witnesses used in proofs, and then prove subsequent facts about this information. Our primitives also decouple state information from the proofs themselves, allowing for modular protocol design. We provide formal definitions for these primitives using a composable security framework, and go on to describe constructions that securely realize these definitions. These primitives can be used as modular building blocks to attenuate the security guarantees of existing protocols in literature, to construct privacy preserving protocols that allow for the collection of statistics about secret information, and to build protocols for other schemes that may benefit from this technique, such as those that involve access control and oblivious transfer. We describe several such protocols in this thesis. We also provide computational cost measurements for our primitives and protocols by way of implementations, in order to show that they are practical for large data structure sizes. We finally provide a notation and a compiler that takes as input a ZK proof represented by said notation and outputs a secure SZK protocol, allowing for a layer of abstraction so that practitioners may specify the security properties and the data structures they wish to use, and be presented with a ready to use implementation without needing to deal with the theoretical aspects of these primitives, essentially bridging the gap between theoretical cryptographic constructions and their implementation. This thesis conveys the results of FNR CORE Junior project, Stateful Zero Knowledge. [less ▲]Detailed reference viewed: 37 (8 UL) A Compiler for Stateful Zero Knowledge Data StructuresDamodaran, Aditya Shyam Shankar ; Rial, Alfredo Software (2022)Detailed reference viewed: 30 (3 UL) Implementations for Unlinkable Updatable Hiding Databases and Privacy-Preserving Loyalty ProgramsDamodaran, Aditya Shyam Shankar ; Rial, Alfredo Software (2021)Detailed reference viewed: 59 (8 UL) Unlinkable Updatable Hiding Databases and Privacy-Preserving Loyalty ProgramsDamodaran, Aditya Shyam Shankar ; Rial, Alfredo in Proceedings on Privacy Enhancing Technologies (2021, July), 2021(3), 95-121Loyalty programs allow vendors to profile buyers based on their purchase histories, which can reveal privacy sensitive information. Existing privacy friendly loyalty programs force buyers to choose ... [more ▼]Loyalty programs allow vendors to profile buyers based on their purchase histories, which can reveal privacy sensitive information. Existing privacy friendly loyalty programs force buyers to choose whether their purchases are linkable. Moreover, vendors receive more purchase data than required for the sake of profiling. We propose a privacy-preserving loyalty program where purchases are always unlinkable, yet a vendor can profile a buyer based on her purchase history, which remains hidden from the vendor. Our protocol is based on a new building block, an unlinkable updatable hiding database (HD), which we define and construct. HD allows the vendor to initialize and update databases stored by buyers that contain their purchase histories and their accumulated loyalty points. Updates are unlinkable and, at each update, the database is hidden from the vendor. Buyers can neither modify the database nor use old versions of it. Our construction for HD is practical for large databases. [less ▲]Detailed reference viewed: 106 (25 UL) Implementations for Unlinkable Updatable Databases and Oblivious Transfer with Access ControlDamodaran, Aditya Shyam Shankar ; Rial, Alfredo Software (2020)Detailed reference viewed: 22 (3 UL) Implementations for UC Updatable Databases and ApplicationsDamodaran, Aditya Shyam Shankar ; Rial, Alfredo Software (2020)Detailed reference viewed: 25 (2 UL) UC Updatable Databases and ApplicationsDamodaran, Aditya Shyam Shankar ; Rial, Alfredo in 12th International Conference on Cryptology (2020)We define an ideal functionality $\Functionality_{\UD}$ and a construction $\mathrm{\Pi_{\UD}}$ for an updatable database ($\UD$). $\UD$ is a two-party protocol between an updater and a reader. The ... [more ▼]We define an ideal functionality $\Functionality_{\UD}$ and a construction $\mathrm{\Pi_{\UD}}$ for an updatable database ($\UD$). $\UD$ is a two-party protocol between an updater and a reader. The updater sets the database and updates it at any time throughout the protocol execution. The reader computes zero-knowledge (ZK) proofs of knowledge of database entries. These proofs prove that a value is stored at a certain position in the database, without revealing the position or the value. (Non-)updatable databases are implicitly used as building block in priced oblivious transfer, privacy-preserving billing and other privacy-preserving protocols. Typically, in those protocols the updater signs each database entry, and the reader proves knowledge of a signature on a database entry. Updating the database requires a revocation mechanism to revoke signatures on outdated database entries. Our construction $\mathrm{\Pi_{\UD}}$ uses a non-hiding vector commitment (NHVC) scheme. The updater maps the database to a vector and commits to the database. This commitment can be updated efficiently at any time without needing a revocation mechanism. ZK proofs for reading a database entry have communication and amortized computation cost independent of the database size. Therefore, $\mathrm{\Pi_{\UD}}$ is suitable for large databases. We implement $\mathrm{\Pi_{\UD}}$ and our timings show that it is practical. In existing privacy-preserving protocols, a ZK proof of a database entry is intertwined with other tasks, e.g., proving further statements about the value read from the database or the position where it is stored. $\Functionality_{\UD}$ allows us to improve modularity in protocol design by separating those tasks. We show how to use $\Functionality_{\UD}$ as building block of a hybrid protocol along with other functionalities. [less ▲]Detailed reference viewed: 194 (27 UL) Unlinkable Updatable Databases and Oblivious Transfer with Access ControlDamodaran, Aditya Shyam Shankar ; Rial, Alfredo in 25th Australasian Conference on Information Security and Privacy (2020)An oblivious transfer with access control protocol (OTAC) allows us to protect privacy of accesses to a database while enforcing access control policies. Existing OTAC have several shortcomings. First ... [more ▼]An oblivious transfer with access control protocol (OTAC) allows us to protect privacy of accesses to a database while enforcing access control policies. Existing OTAC have several shortcomings. First, their design is not modular. Typically, to create an OTAC, an adaptive oblivious transfer protocol (OT) is extended ad-hoc. Consequently, the security of the OT is reanalyzed when proving security of the OTAC, and it is not possible to instantiate the OTAC with any secure OT. Second, existing OTAC do not allow for policy updates. Finally, in practical applications, many messages share the same policy. However, existing OTAC cannot take advantage of that to improve storage efficiency. We propose an UC-secure OTAC that addresses the aforementioned shortcomings. Our OTAC uses as building blocks the ideal functionalities for OT, for zero-knowledge (ZK) and for an \emph{unlinkable updatable database} ($\UUD$), which we define and construct. $\UUD$ is a protocol between an updater $\fuudUpdater$ and multiple readers $\fuudReader_k$. $\fuudUpdater$ sets up a database and updates it. $\fuudReader_k$ can read the database by computing UC ZK proofs of an entry in the database, without disclosing what entry is read. In our OTAC, $\UUD$ is used to store and read the policies. We construct an $\UUD$ based on subvector commitments (SVC). We extend the definition of SVC with update algorithms for commitments and openings, and we provide an UC ZK proof of a subvector. Our efficiency analysis shows that our $\UUD$ is practical. [less ▲]Detailed reference viewed: 208 (42 UL) UC Priced Oblivious Transfer with Purchase Statistics and Dynamic PricingDamodaran, Aditya Shyam Shankar ; Dubovitskaya, Maria; Rial, Alfredo in Progress in Cryptology – INDOCRYPT 2019 (2019, December)Priced oblivious transfer (POT) is a cryptographic protocol that can be used to protect customer privacy in e-commerce applications. Namely, it allows a buyer to purchase an item from a seller without ... [more ▼]Priced oblivious transfer (POT) is a cryptographic protocol that can be used to protect customer privacy in e-commerce applications. Namely, it allows a buyer to purchase an item from a seller without disclosing to the latter which item was purchased and at which price. Unfortunately, existing POT schemes have some drawbacks in terms of design and functionality. First, the design of existing POT schemes is not modular. Typically, a POT scheme extends a k-out-of-N oblivious transfer (OT) scheme by adding prices to the items. However, all POT schemes do not use OT as a black-box building block with certain security guarantees. Consequently, security of the OT scheme needs to be reanalyzed while proving security of the POT scheme, and it is not possible to swap the underlying OT scheme with any other OT scheme. Second, existing POT schemes do not allow the seller to obtain any kind of statistics about the buyer's purchases, which hinders customer and sales management. Moreover, the seller is not able to change the prices of items without restarting the protocol from scratch. We propose a POT scheme that addresses the aforementioned drawbacks. We prove the security of our POT in the UC framework. We modify a standard POT functionality to allow the seller to receive aggregate statistics about the buyer's purchases and to change prices dynamically. We present a modular construction for POT that realizes our functionality in the hybrid model. One of the building blocks is an ideal functionality for OT. Therefore, our protocol separates the tasks carried out by the underlying OT scheme from the additional tasks needed by a POT scheme. Thanks to that, our protocol is a good example of modular design and can be instantiated with any secure OT scheme as well as other building blocks without reanalyzing security from scratch. [less ▲]Detailed reference viewed: 192 (54 UL) 1