9,608 research outputs found
VĂ©letlenszerű fluktuáciĂłk analĂzisĂ©n Ă©s hasznosĂtásán alapulĂł mĂ©rĂ©si Ă©s titkosĂtási eljárások vizsgálata
Random signals - "noises" - aren’t necessarily hindrances to be eliminated, they can carry information about the examined system. They can also play a constructive role - optimal functioning of some systems are made only possible by appropriate noise application. In the dissertation results are presented in areas which are examples of utilising noises in a constructive role or as an information source.
The subject of the first half of the thesis is the analysis of the Kirchhoff-Law-Johnson-Noise (KLJN) secure key exchange protocol. First, the necessary and sufficient conditions of noise properties for unconditional security are deducted using the tools of mathematical statistics only, giving a mathematical proof for the system's perfect security. Next, the generalization of the protocol is presented, allowing the two communicating parties to use different hardware, i.e. resistors with different values. This result not only makes the practical application of the protocol much easier, but resulted in the reinterpretation of the classical physical description of the original KLJN protocol’s security . Finally the supplement of the generalized protocol is presented, in which the components previously bringing non-ideality and information leakage into the system became a part of the unconditionally secure ideal system, which is evidently a big step forward for the protocol's practical applications.
Thereafter a new field of application for using fluctuations as an information source is shown. The presented results about analyzing kayak paddlers' motion signals pointed out that the quality of the paddling is correlated to the fluctuation of the period and stroke impulse, which characterise the period of the motion. Thus the temporal indicators characterizing the period fluctuations and the spectral indicators based on the raw motion signals' signal-to-noise ratio could contain extra information. The latter method of spectral variability analysis could be useful for other periodic signals as well
Error-Correction in Flash Memories via Codes in the Ulam Metric
We consider rank modulation codes for flash memories that allow for handling
arbitrary charge-drop errors. Unlike classical rank modulation codes used for
correcting errors that manifest themselves as swaps of two adjacently ranked
elements, the proposed \emph{translocation rank codes} account for more general
forms of errors that arise in storage systems. Translocations represent a
natural extension of the notion of adjacent transpositions and as such may be
analyzed using related concepts in combinatorics and rank modulation coding.
Our results include derivation of the asymptotic capacity of translocation rank
codes, construction techniques for asymptotically good codes, as well as simple
decoding methods for one class of constructed codes. As part of our exposition,
we also highlight the close connections between the new code family and
permutations with short common subsequences, deletion and insertion
error-correcting codes for permutations, and permutation codes in the Hamming
distance
Exoplanets and SETI
The discovery of exoplanets has both focused and expanded the search for
extraterrestrial intelligence. The consideration of Earth as an exoplanet, the
knowledge of the orbital parameters of individual exoplanets, and our new
understanding of the prevalence of exoplanets throughout the galaxy have all
altered the search strategies of communication SETI efforts, by inspiring new
"Schelling points" (i.e. optimal search strategies for beacons). Future efforts
to characterize individual planets photometrically and spectroscopically, with
imaging and via transit, will also allow for searches for a variety of
technosignatures on their surfaces, in their atmospheres, and in orbit around
them. In the near-term, searches for new planetary systems might even turn up
free-floating megastructures.Comment: 9 page invited review. v2 adds some references and v3 has other minor
additions and modification
Effective Privacy Amplification for Secure Classical Communications
We study the practical effectiveness of privacy amplification for classical
key-distribution schemes. We find that in contrast to quantum key distribution
schemes, the high fidelity of the raw key generated in classical systems allow
the users to always sift a secure shorter key if they have an upper bound on
the eavesdropper probability to correctly guess the exchanged key-bits. The
number of privacy amplification iterations needed to achieve information leak
of 10^-8 in existing classical communicators is 2 or 3 resulting in a
corresponding slowdown 4 to 8. We analyze the inherent tradeoff between the
number of iterations and the security of the raw key. This property which is
unique to classical key distribution systems render them highly useful for
practical, especially for noisy channels where sufficiently low quantum bit
error ratios are difficult to achieve.Comment: 11 pages, 3 figure
- …