International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Ratna Dutta

Publications

Year
Venue
Title
2017
PKC
2016
PKC
2015
EPRINT
2015
EPRINT
2015
EPRINT
2014
EPRINT
2006
EPRINT
Repairing Attacks on a Password-Based Group Key Agreement
Ratna Dutta Rana Barua
From designing point of view, it is not a trivial task to convert a group key agreement protocol into password-based setting where the members of the group share only a human-memorable weak password and the system may not have any secure public key infrastructure. Security analysis against dictionary attacks is on the other side of the coin. The low entropy of human memorable password may enable an adversary to mount off-line dictionary attacks if careful approaches are not taken in designing the protocol. Recently, Kim et al. proposed a very efficient provably secure group key agreement protocol KLL, security of which relies on the Computational Diffie-Hellman (CDH) assumption in the presence of random oracles. Dutta-Barua embed the protocol KLL into password-based environment -- yielding the protocol DB-PWD. Abdalla et al. detect certain flaws in the protocol DB-PWD. In this paper, we take suitable measures to overcome these attacks. We introduce a protocol MDB-PWD -- an improved variant of the protocol DB-PWD and analyze its security in the security framework formalized by Bellare et al. in both the ideal cipher model and the random oracle model under CDH assumption.
2005
EPRINT
Dynamic Group Key Agreement in Tree-Based Setting
Ratna Dutta Rana Barua
We present a provably secure tree based authenticated group key agreement protocol in dynamic scenario. Bilinear pairing and multi-signature are at the heart of our protocol. We prove that our protocol is provably secure in the standard security model of Bresson et al. An appropriate modification of Katz-Yung approach to tree based setting is adopted while proving its security against active adversaries. The protocol has an in-built hierarchical structure that makes it desirable for certain applications.
2005
EPRINT
Constant Round Dynamic Group Key Agreement
Ratna Dutta Rana Barua
We present a fully symmetric constant round authenticated group key agreement protocol in dynamic scenario. Our proposed scheme achieves forward secrecy and is provably secure under DDH assumption in the security model of Bresson {\em et al.} providing, we feel, better security guarantee than previously published results. The protocol is efficient in terms of both communication and computation power.
2005
EPRINT
Overview of Key Agreement Protocols
Ratna Dutta Rana Barua
The emphasis of this paper is to focus on key agreement. To this aim, we address a self-contained, up-to-date presentation of key agreement protocols at high level. We have attempted to provide a brief but fairly complete survey of all these schemes.
2004
EPRINT
Pairing-Based Cryptographic Protocols : A Survey
The bilinear pairing such as Weil pairing or Tate pairing on elliptic and hyperelliptic curves have recently been found applications in design of cryptographic protocols. In this survey, we have tried to cover different cryptographic protocols based on bilinear pairings which possess, to the best of our knowledge, proper security proofs in the existing security models.
2004
EPRINT
Provably Secure Authenticated Tree Based Group Key Agreement Protocol
We present a provably secure authenticated tree based key agreement protocol. The protocol is obtained by combining Boldyreva's multi-signature with an unauthenticated ternary tree based multi-party extension of Joux's key agreement protocol. The securiry is in the standard model as formalized by Bresson et al. The proof is based on the techniques used by Katz and Yung in proving the security of their key agreement protocol.
2003
EPRINT
Extending Joux's Protocol to Multi Party Key Agreement
We present a secure unauthenticated as well as an authenticated multi party key agreement protocol. The unauthenticated version of our protocol uses ternary trees and is based on bilinear maps and Joux's three party protocol. The number of rounds, computation/communication complexity of our protocol compares favourably with previously known protocols. The authenticated version of our protocol also uses ternary trees and is based on public IDs and Key Generation Centres. The authenticated version of our protocol is more efficient than all previously known authenticated key agreement protocols.