Research

Provable Security of Symmetric-Key Cryptography

My primary research interest is the provable security analysis of symmetric-key cryptographic modes using combinatorial techniques. My doctoral research focused on provable security against a classical adversary. At Inria, I started exploring the exciting new field of provable security against a quantum adversary, as part of the ERC project QUASYModo. At present I am studying proof frameworks for adapting classical counting techniques in post-quantum security proofs.

My complete academic CV (last updated in February 2026) can be found here: [PDF] link to CV. My publications are also listed on my DBLP page.

Publications

The Key Control Security of KDF Combiners.
SCN '26 (to appear).
ePrint

Pencil: A Domain-Extended Committing BBB PRF for Strengthening GCM.
Crypto '26 (to appear).
(with Jean Paul Degabriele and Chandranan Dhar) ePrint

How to Build a Short-Input Random Oracle from Public Random Permutations.
Eurocrypt '26.
(with Nilanjan Datta, Avijit Dutta, Ashwin Jha, Sougata Mandal, Bart Mennink, Hrithik Nandi and Yaobin Shen) DOI ePrint

Breaking and Fixing Macakey.
Transactions on Symmetric Cryptology 2026(1).
(with Bishwajit Chakraborty and Chandranan Dhar) DOI ePrint

Post-quantum Security of Key-Alternating Feistel Ciphers.
Asiacrypt '25.
(with Jyotirmoy Basak, Amit Kumar Chauhan, Ravindra Jejurikar, Ashwin Jha, Anandarup Roy, André Schrottenloher and Suprita Talnikar) DOI ePrint

Cryptographic Treatment of Key Control Security In Light of NIST SP 800-108.
Crypto '25.
(with Avijit Dutta, Akiko Inoue, Tetsu Iwata, Ashwin Jha, Kazuhiko Minematsu, Mridul Nandi, Yu Sasaki, Meltem Sönmez Turan and Stefano Tessaro) DOI ePrint

Building a BBB Pseudorandom Permutation using Lai-Massey Networks.
Communications in Cryptology 1(4).
(with Mohammad Amin Raeisi) DOI ePrint

Block Cipher Doubling for a Post-Quantum World.
Communications in Cryptology 1(3).
(with André Chailloux, Paul Frixons, Bart Mennink and María Naya-Plasencia) DOI ePrint

Mind the Bad Norms: Revisiting Compressed Oracle-based Quantum Indistinguishability Proofs.
Asiacrypt '24.
(with Benoît Cogliati, Jordan Ethan and Ashwin Jha) DOI ePrint

Efficient Variants of TNT with BBB Security.
ProvSec '24.
(with Bishwajit Chakraborty, Wonseok Choi, Avijit Dutta, Cuauhtemoc Mancillas López, Hrithik Nandi and Yaobin Shen) DOI ePrint

Indifferentiability of Confusion-Diffusion Networks.
SCN '24.
(with Mridul Nandi, Sayantan Paul and Abishanka Saha) DOI

Provably Secure Online Authenticated Encryption and Bidirectional Online Channels.
SAC '24.
(with Arghya Bhattacharjee, Daniel Collins and Mridul Nandi) DOI ePrint

The Committing Security of MACs with Applications to Generic Composition.
Crypto '24.
(with Bishwajit Chakraborty, Wonseok Choi, Avijit Dutta, Jérôme Govinden and Yaobin Shen) DOI ePrint

On Quantum-Secure Compressing Pseudorandom Functions.
Asiacrypt '23.
(with Benoît Cogliati, Jordan Ethan and Ashwin Jha) DOI ePrint

BBB-Security for 5-Round Even-Mansour-Based Key-Alternating Feistel Ciphers.
Designs, Codes and Cryptography 92(1).
(with Arghya Bhattacharjee, Avijit Dutta, Mridul Nandi and Anik Raychaudhuri) DOI

PAE: Towards More Efficient and BBB-secure AE From a Single Public Permutation.
ICICS '23.
(with Arghya Bhattacharjee, Avijit Dutta and Eik List) DOI ePrint

Revisiting the Indifferentiability of the Sum of Permutations.
Crypto '23.
(with Aldo Gunsing, Ashwin Jha, Bart Mennink and Yaobin Shen) DOI ePrint

Offset-Based BBB-Secure Tweakable Block-ciphers with Updatable Caches.
Indocrypt '22.
(with Arghya Bhattacharjee and Mridul Nandi) DOI ePrint

A Sponge-Based PRF with Good Multi-user Security.
SAC '22.
(with Arghya Bhattacharjee and Mridul Nandi) DOI ePrint

Improved indifferentiability security proof for 3-round tweakable Luby-Rackoff.
Designs, Codes and Cryptography 89(10).
(with Mridul Nandi and Anik Raychaudhuri) DOI

QCB: Efficient Quantum-Secure Authenticated Encryption.
Asiacrypt '21.
(with Xavier Bonnetain, André Chailloux, Gaëtan Leurent, María Naya-Plasencia, André Schrottenloher and Yannick Seurin) DOI ePrint

ZCZ - Achieving n-bit SPRP Security with a Minimal Number of Tweakable-Block-Cipher Calls.
Asiacrypt '18.
(with Eik List and Mridul Nandi) DOI ePrint

Turning Online Ciphers Off.
Transactions on Symmetric Cryptology 2017(2).
(with Elena Andreeva, Guy Barwell, Daniel Page, Mridul Nandi and Martijn Stam) DOI ePrint

Improved Security for OCB3.
Asiacrypt '17.
(with Mridul Nandi) DOI ePrint

The Iterated Random Function Problem.
Asiacrypt '17.
(with Nilanjan Datta, Avijit Dutta, Nicky Mouha and Mridul Nandi) DOI ePrint

OleF: an Inverse-Free Online Cipher.
Transactions on Symmetric Cryptology 2016(2).
(with Mridul Nandi) DOI ePrint

An Inverse-Free Single-Keyed Tweakable Enciphering Scheme.
Asiacrypt '15.
(with Mridul Nandi) DOI ePrint

Notes & Preprints

A Note on Feedback-PRF Mode of KDF from NIST SP 800-108.
(with Avijit Dutta, Tetsu Iwata, Ashwin Jha, Kazuhiko Minematsu, Mridul Nandi, Yu Sasaki, Meltem Sönmez Turan and Stefano Tessaro) ePrint

BBB Secure Large-Tweak TBC from Ideal Block Ciphers.
(with Arghya Bhattacharjee, Nilanjan Datta, Avijit Dutta, Shibam Ghosh and Sougata Mandal) ePrint

Universal Context Commitment without Ciphertext Expansion.
(with Arghya Bhattacharjee and Chandranan Dhar) ePrint

Indifferentiability of 6-round Feistel.
(with Ashwin Jha, Mridul Nandi, Sayantan Paul and Abishanka Saha)