211 research outputs found
Advance in Keyless Cryptography
The term “keyless cryptography” as it is commonly adopted, applies to secure message transmission either directly without any key distribution in advance or as key sharing protocol between communicating users, based on physical layer security, before ordinary encryption/decryption procedures. In the current chapter the results are presented concerning to keyless cryptography that have been obtained by authors recently. Firstly Shamir’s protocol of secure communication is considered where commutative encryption procedure is executed. It has been found out which of the public key algorithms can be used with such protocol. Next item of consideration concerns Dean’s and Goldsmith’s cryptosystem based on multiple-input, multiple-output (MIMO) technology. It has been established under which conditions this cryptosystem is in fact secure. The third example under consideration is EVSkey scheme proposed recently by D. Qin and Z. Ding. It has been proven that such key distribution method is in fact insecure, in spite of the authors’ claims. Our main result is a description of a key sharing protocol executing over public noiseless channels (like internet) that provides a key sharing reliability and security without any cryptographic assumptions
Principles of Physical Layer Security in Multiuser Wireless Networks: A Survey
This paper provides a comprehensive review of the domain of physical layer
security in multiuser wireless networks. The essential premise of
physical-layer security is to enable the exchange of confidential messages over
a wireless medium in the presence of unauthorized eavesdroppers without relying
on higher-layer encryption. This can be achieved primarily in two ways: without
the need for a secret key by intelligently designing transmit coding
strategies, or by exploiting the wireless communication medium to develop
secret keys over public channels. The survey begins with an overview of the
foundations dating back to the pioneering work of Shannon and Wyner on
information-theoretic security. We then describe the evolution of secure
transmission strategies from point-to-point channels to multiple-antenna
systems, followed by generalizations to multiuser broadcast, multiple-access,
interference, and relay networks. Secret-key generation and establishment
protocols based on physical layer mechanisms are subsequently covered.
Approaches for secrecy based on channel coding design are then examined, along
with a description of inter-disciplinary approaches based on game theory and
stochastic geometry. The associated problem of physical-layer message
authentication is also introduced briefly. The survey concludes with
observations on potential research directions in this area.Comment: 23 pages, 10 figures, 303 refs. arXiv admin note: text overlap with
arXiv:1303.1609 by other authors. IEEE Communications Surveys and Tutorials,
201
Commitment and Oblivious Transfer in the Bounded Storage Model with Errors
The bounded storage model restricts the memory of an adversary in a
cryptographic protocol, rather than restricting its computational power, making
information theoretically secure protocols feasible. We present the first
protocols for commitment and oblivious transfer in the bounded storage model
with errors, i.e., the model where the public random sources available to the
two parties are not exactly the same, but instead are only required to have a
small Hamming distance between themselves. Commitment and oblivious transfer
protocols were known previously only for the error-free variant of the bounded
storage model, which is harder to realize
Information-theoretic Physical Layer Security for Satellite Channels
Shannon introduced the classic model of a cryptosystem in 1949, where Eve has
access to an identical copy of the cyphertext that Alice sends to Bob. Shannon
defined perfect secrecy to be the case when the mutual information between the
plaintext and the cyphertext is zero. Perfect secrecy is motivated by
error-free transmission and requires that Bob and Alice share a secret key.
Wyner in 1975 and later I.~Csisz\'ar and J.~K\"orner in 1978 modified the
Shannon model assuming that the channels are noisy and proved that secrecy can
be achieved without sharing a secret key. This model is called wiretap channel
model and secrecy capacity is known when Eve's channel is noisier than Bob's
channel.
In this paper we review the concept of wiretap coding from the satellite
channel viewpoint. We also review subsequently introduced stronger secrecy
levels which can be numerically quantified and are keyless unconditionally
secure under certain assumptions. We introduce the general construction of
wiretap coding and analyse its applicability for a typical satellite channel.
From our analysis we discuss the potential of keyless information theoretic
physical layer security for satellite channels based on wiretap coding. We also
identify system design implications for enabling simultaneous operation with
additional information theoretic security protocols
Cryptography Based on Correlated Data: Foundations and Practice
Correlated data can be very useful in cryptography. For instance, if a uniformly random key is available to Alice and Bob, it can be used as an one-time pad to transmit a message with perfect security. With more elaborate forms of correlated data, the parties can achieve even more complex cryptographic tasks, such as secure multiparty computation. This thesis explores (from both a theoretical and a practical point of view) the topic of cryptography based on correlated data
Ideal quantum protocols in the non-ideal physical world
The development of quantum protocols from conception to experimental realizations is one of
the main sources of the stimulating exchange between fundamental and experimental research
characteristic to quantum information processing. In this thesis we contribute to the development
of two recent quantum protocols, Universal Blind Quantum Computation (UBQC) and Quantum
Digital Signatures (QDS). UBQC allows a client to delegate a quantum computation to a more
powerful quantum server while keeping the input and computation private. We analyse the resilience
of the privacy of UBQC under imperfections. Then, we introduce approximate blindness
quantifying any compromise to privacy, and propose a protocol which enables arbitrary levels of
security despite imperfections. Subsequently, we investigate the adaptability of UBQC to alternative
implementations with practical advantages. QDS allow a party to send a message to other
parties which cannot be forged, modified or repudiated. We analyse the security properties of a
first proof-of-principle experiment of QDS, implemented in an optical system. We estimate the
security failure probabilities of our system as a function of protocol parameters, under all but the
most general types of attacks. Additionally, we develop new techniques for analysing transformations
between symmetric sets of states, utilized not only in the security proofs of QDS but in
other applications as well
Unconditional security from noisy quantum storage
We consider the implementation of two-party cryptographic primitives based on
the sole assumption that no large-scale reliable quantum storage is available
to the cheating party. We construct novel protocols for oblivious transfer and
bit commitment, and prove that realistic noise levels provide security even
against the most general attack. Such unconditional results were previously
only known in the so-called bounded-storage model which is a special case of
our setting. Our protocols can be implemented with present-day hardware used
for quantum key distribution. In particular, no quantum storage is required for
the honest parties.Comment: 25 pages (IEEE two column), 13 figures, v4: published version (to
appear in IEEE Transactions on Information Theory), including bit wise
min-entropy sampling. however, for experimental purposes block sampling can
be much more convenient, please see v3 arxiv version if needed. See
arXiv:0911.2302 for a companion paper addressing aspects of a practical
implementation using block samplin
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