arXiv subjects

Kunal Dey

Publications and source records attributed to Kunal Dey.

6 recordsLinked to original sources

arXiv2026

Hierarchical Identity-Based Signature with Designated Aggregator from Lattices

In hierarchical organizations, authenticating data from multiple users can be complex and resource-intensive. Hierarchical Identity-Based Signature with Designated Aggregator (HIBS-DA) provides an efficient solution by allowing users at different levels to generate signatures that can be combined into a single, compact signature. We first introduce the HIBS-DA framework and present the {\em{first}} lattice-based construction of HIBS-DA. Our scheme allows users at different hierarchical levels to generate individual signatures that can be aggregated into a single, compact signature, reducing communication and verification costs. The proposed construction is secure, correct, and resistant to forgery, making it suitable for large-scale environments such as universities, corporations, and government agencies.

cs.CR↗

arXiv2026

Hybrid Encryption with Certified Deletion in Preprocessing Model

Certified deletion allows Alice to outsource data to Bob and, at a later time, obtain a verifiable guarantee that the file has been irreversibly deleted at her request. This functionality, while impossible using classical information alone, can be achieved using quantum information. Existing approaches rely either on one-time pad (OTP) encryption or on computational hardness assumptions that may be vulnerable to future advances in classical or quantum computing. In this work, we introduce and formalize hybrid encryption with certified deletion in the preprocessing model (pHE-CD) and propose two constructions. Each construction composes an information-theoretic key encapsulation mechanism (iKEM) with a data encapsulation mechanism that provides certified deletion (DEM-CD) security, offering different security guarantees depending on the properties of DEM-CD. When DEM-CD is one-time information-theoretically secure, the composition provides information-theoretic security for both encryption and certified deletion. When DEM-CD is computationally secure, the composed construction provides computationally secure (post-quantum) encryption and everlasting certified deletion, where confidentiality is computational until the deletion certificate is successfully verified. After successful verification, confidentiality becomes unconditional. That is, successful verification of the deletion certificate guarantees that the data has been removed information-theoretically from the adversary's view. Both pHE-CD constructions support the encryption of arbitrarily long messages. Construction 2 is key-efficient and uses a DEM-CD built from quantum coding and AES, providing quantum-safe security for encryption. We conclude by discussing the implications of our results and directions for future research.

cs.CR↗

arXiv2025

Secure Composition of Quantum Key Distribution and Symmetric Key Encryption

Quantum key distribution (QKD) allows Alice and Bob to share a secret key over an insecure channel with proven information-theoretic security against an adversary whose strategy is bounded only by the laws of physics. Composability-based security proofs of QKD ensure that using the established key with a one-time-pad encryption scheme provides information theoretic secrecy for the message. In this paper, we consider the problem of using the QKD established key with a secure symmetric key-based encryption algorithm and use an approach based on hybrid encryption to provide a proof of security for the composition. Hybrid encryption was first proposed as a public key cryptographic algorithm with proven security for messages of unrestricted length. We use an extension of this framework to correlated randomness setting (Sharifian et al. in ISIT 2021) to propose a quantum-enabled Key Encapsulation Mechanism (qKEM) and quantum-enabled hybrid encryption (qHE), and prove a composition theorem for the security of the qHE. We construct a qKEM with proven security using an existing QKD (Portmann et al. in Rev. of Mod. Physics 2022). Using this qKEM with a secure Data Encapsulation Mechanism (DEM), that can be constructed using a one-time symmetric key encryption scheme, results in an efficient encryption system for unrestricted length messages with proved security against an adversary with access to efficient computations on a quantum computer (i.e. post-quantum secure encryption without using any computational assumptions.)

quant-ph↗

arXiv2024

An Undeniable Signature Scheme Utilizing Module Lattices

An undeniable signature scheme is type of digital signature where the signer retains control over the signature's verifiability. Therefore with the approval of the signer, only an authenticated verifier can verify the signature. In this work, we develop a module lattice-based post-quantum undeniable signature system. Our method is based on the GPV framework utilizing module lattices, with the security assured by the hardness of the SIS and LWE problems. We have thoroughly proved all the desired securities for the proposed scheme. Finally, we have implemented our protocol for different sets of parameters. The purpose of opting a module variant rather than a ring variant is to provide greater flexibility in selecting parameters.

cs.CR↗

arXiv2024

Isogeny-based Post-Quantum Proxy Signature for Internet of Things

The rapid growth of the Internet of Things (IoT) introduces challenges in secure authentication and delegation due to the limited computational capabilities of devices. Proxy signature schemes offer an effective solution by enabling controlled delegation of signing rights to more capable entities, such as gateway nodes. However, most existing schemes rely on classical assumptions that are likely to be broken by quantum adversaries. In this work, we address these challenges by proposing an isogeny-based post-quantum proxy signature scheme, \textit{CSI-PS}. The scheme leverages the hardness of the Group Action Inverse Problem (GAIP) to ensure quantum-resistant security while maintaining efficiency suitable for resource-constrained environments. We further demonstrate its applicability in IoT architectures through a gateway-based delegation model. Our analysis shows that the proposed scheme strikes an effective balance between security and efficiency in terms of computation and communication overhead, along with provable security under the EUF-CMA notion.

cs.CR↗

arXiv2023

Flexible polar encoding for information reconciliation in QKD

Quantum Key Distribution (QKD) enables two parties to establish a common secret key that is information-theoretically secure by transmitting random bits that are encoded as qubits and sent over a quantum channel, followed by classical information processing steps known as information reconciliation and key extraction. Transmission of information over a quantum channel introduces errors that are generally considered to be due to the adversary's tempering with the quantum channel and needs to be corrected using classical communication over an (authenticated) public channel. Commonly used error-correcting codes in the context of QKD include cascade codes, low-density parity check (LDPC) codes, and more recently polar codes. In this work, we explore the applicability of designing of a polar code encoder based on a channel reliability sequence. We show that the reliability sequence can be derived and used to design an encoder independent of the choice of decoder. We then implement our design and evaluate its performance against previous implementations of polar code encoders for QKD as well as other typical error-correcting codes. A key advantage of our approach is the modular design which decouples the encoder and decoder design and allows independent optimization of each. Our work leads to more versatile polar code-based error reconciliation in QKD systems that would result in deployment in a broader range of scenarios.

quant-ph↗