10 research outputs found
A Note on the Information-Theoretic-(in)Security of Fading Generated Secret Keys
In this work we explore the security of secret keys generated via the
electromagnetic reciprocity of the wireless fading channel. Identifying a new
sophisticated colluding attack, we explore the information-theoretic-security
for such keys in the presence of an all-powerful adversary constrained only by
the laws of quantum mechanics. Specifically, we calculate the reduction in the
conditional mutual information between transmitter and receiver that can occur
when an adversary with unlimited computational and communication resources
places directional antenna interceptors at chosen locations. Such locations, in
principal, can be arbitrarily far from the intended receiver yet still
influence the secret key rate.Comment: 4 pages, 2 figures. This work has been submitted to the IEEE for
possible publication. Copyright may be transferred without notice, after
which this version may no longer be accessibl
Secret Key Agreement from Correlated Data, with No Prior Information
A fundamental question that has been studied in cryptography and in
information theory is whether two parties can communicate confidentially using
exclusively an open channel. We consider the model in which the two parties
hold inputs that are correlated in a certain sense. This model has been studied
extensively in information theory, and communication protocols have been
designed which exploit the correlation to extract from the inputs a shared
secret key. However, all the existing protocols are not universal in the sense
that they require that the two parties also know some attributes of the
correlation. In other words, they require that each party knows something about
the other party's input. We present a protocol that does not require any prior
additional information. It uses space-bounded Kolmogorov complexity to measure
correlation and it allows the two legal parties to obtain a common key that
looks random to an eavesdropper that observes the communication and is
restricted to use a bounded amount of space for the attack. Thus the protocol
achieves complexity-theoretical security, but it does not use any unproven
result from computational complexity. On the negative side, the protocol is not
efficient in the sense that the computation of the two legal parties uses more
space than the space allowed to the adversary.Comment: Several small errors have been fixed and the presentation has been
improved, following the reviewers' observation
Shared Information for a Markov Chain on a Tree
Shared information is a measure of mutual dependence among multiple jointly
distributed random variables with finite alphabets. For a Markov chain on a
tree with a given joint distribution, we give a new proof of an explicit
characterization of shared information. The Markov chain on a tree is shown to
possess a global Markov property based on graph separation; this property plays
a key role in our proofs. When the underlying joint distribution is not known,
we exploit the special form of this characterization to provide a multiarmed
bandit algorithm for estimating shared information, and analyze its error
performance.Comment: 13 pages, 4 figures, submitted to IEEE Transactions on Information
Theor
Multiterminal secrecy by public discussion
Multiterminal Secrecy by Public Discussion describes the principles of information theoretic secrecy generation by legitimate parties with public discussion in the presence of an eavesdropper