Publications de Ritam Bhaumik | EPFL Graph Search

Provably Secure Online Authenticated Encryption and Bidirectional Online Channels

In this work, we examine online authenticated encryption with variable expansion. We follow a notion where both encryption and decryption are online, and security is ensured in the RUP (Release of Unverified Plaintext) setting. Then we propose a generic wa ...

Springer Science and Business Media Deutschland GmbH2025

PAE: Towards More Efficient and BBB-Secure AE from a Single Public Permutation

Ritam Bhaumik

Four recent trends have emerged in the evolution of authenticated encryption schemes: (1) Regarding simplicity, the adoption of public permutations as primitives allows for sparing a key schedule and the need for storing round keys; (2) using the sums of p ...

Springer2023

Revisiting the Indifferentiability of the Sum of Permutations

Ritam Bhaumik

The sum of two n-bit pseudorandom permutations is known to behave like a pseudorandom function with n bits of security. A recent line of research has investigated the security of two public n-bit permutations and its degree of indifferentiability. Mandal e ...

Springer2023

BBB security for 5-round even-Mansour-based key-alternating Feistel ciphers

Ritam Bhaumik

In this paper, we study the security of the Key-Alternating Feistel (KAF) ciphers, a class of key alternating ciphers with the Feistel structure, where each round of the cipher is instantiated with n-bit public round permutation Pi\documentclass[12pt]{mini ...

SPRINGER2023

On Quantum Secure Compressing Pseudorandom Functions

Ritam Bhaumik

In this paper we characterize all 2n-bit-to-n-bit Pseudorandom Functions (PRFs) constructed with the minimum number of calls to n-bit-to-n-bit PRFs and arbitrary number of linear functions. First, we show that all two-round constructions are either classic ...

2023