7,182 research outputs found
Key recycling in authentication
In their seminal work on authentication, Wegman and Carter propose that to
authenticate multiple messages, it is sufficient to reuse the same hash
function as long as each tag is encrypted with a one-time pad. They argue that
because the one-time pad is perfectly hiding, the hash function used remains
completely unknown to the adversary.
Since their proof is not composable, we revisit it using a composable
security framework. It turns out that the above argument is insufficient: if
the adversary learns whether a corrupted message was accepted or rejected,
information about the hash function is leaked, and after a bounded finite
amount of rounds it is completely known. We show however that this leak is very
small: Wegman and Carter's protocol is still -secure, if
-almost strongly universal hash functions are used. This implies
that the secret key corresponding to the choice of hash function can be reused
in the next round of authentication without any additional error than this
.
We also show that if the players have a mild form of synchronization, namely
that the receiver knows when a message should be received, the key can be
recycled for any arbitrary task, not only new rounds of authentication.Comment: 17+3 pages. 11 figures. v3: Rewritten with AC instead of UC. Extended
the main result to both synchronous and asynchronous networks. Matches
published version up to layout and updated references. v2: updated
introduction and reference
Quantum Cryptography in Practice
BBN, Harvard, and Boston University are building the DARPA Quantum Network,
the world's first network that delivers end-to-end network security via
high-speed Quantum Key Distribution, and testing that Network against
sophisticated eavesdropping attacks. The first network link has been up and
steadily operational in our laboratory since December 2002. It provides a
Virtual Private Network between private enclaves, with user traffic protected
by a weak-coherent implementation of quantum cryptography. This prototype is
suitable for deployment in metro-size areas via standard telecom (dark) fiber.
In this paper, we introduce quantum cryptography, discuss its relation to
modern secure networks, and describe its unusual physical layer, its
specialized quantum cryptographic protocol suite (quite interesting in its own
right), and our extensions to IPsec to integrate it with quantum cryptography.Comment: Preprint of SIGCOMM 2003 pape
A quantum key distribution protocol for rapid denial of service detection
We introduce a quantum key distribution protocol designed to expose fake
users that connect to Alice or Bob for the purpose of monopolising the link and
denying service. It inherently resists attempts to exhaust Alice and Bob's
initial shared secret, and is 100% efficient, regardless of the number of
qubits exchanged above the finite key limit. Additionally, secure key can be
generated from two-photon pulses, without having to make any extra
modifications. This is made possible by relaxing the security of BB84 to that
of the quantum-safe block cipher used for day-to-day encryption, meaning the
overall security remains unaffected for useful real-world cryptosystems such as
AES-GCM being keyed with quantum devices.Comment: 13 pages, 3 figures. v2: Shifted focus of paper towards DoS and added
protocol 4. v1: Accepted to QCrypt 201
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
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