Johnson(-like)-Noise-Kirchhoff-Loop Based Secure Classical Communicator Characteristics, for Ranges of Two to Two Thousand Kilometers, via Model-Line

A pair of Kirchhoff-Loop-Johnson(-like)-Noise communicators, which is able to work over variable ranges, was designed and built. Tests have been carried out on a model-line performance characteristics were obtained for ranges beyond the ranges of any known direct quantum communication channel and they indicate unrivalled signal fidelity and security performance of the exchanged raw key bits. This simple device has single-wire secure key generation and sharing rates of 0.1, 1, 10, and 100 bit/second for corresponding copper wire diameters/ranges of 21 mm / 2000 km, 7 mm / 200 km, 2.3 mm / 20 km, and 0.7 mm / 2 km, respectively and it performs with 0.02% raw-bit error rate (99.98 % fidelity). The raw-bit security of this practical system significantly outperforms raw-bit quantum security. Current injection breaking tests show zero bit eavesdropping ability without triggering the alarm signal, therefore no multiple measurements are needed to build an error statistics to detect the eavesdropping as in quantum communication. Wire resistance based breaking tests of Bergou-Scheuer-Yariv type give an upper limit of eavesdropped raw bit ratio of 0.19 % and this limit is inversely proportional to the sixth power of cable diameter. Hao's breaking method yields zero (below measurement resolution) eavesdropping information.Comment: Featured in New Scientist, Jason Palmer, May 23, 2007. http://www.ece.tamu.edu/%7Enoise/news_files/KLJN_New_Scientist.pdf Corresponding Plenary Talk at the 4th International Symposium on Fluctuation and Noise, Florence, Italy (May 23, 2007

Totally Secure Classical Communication Utilizing Johnson (-like) Noise and Kirchoff's Law

An absolutely secure, fast, inexpensive, robust, maintenance-free and low-power- consumption communication is proposed. The states of the information bit are represented by two resistance values. The sender and the receiver have such resistors available and they randomly select and connect one of them to the channel at the beginning of each clock period. The thermal noise voltage and current can be observed but Kirchoff's law provides only a second-order equation. A secure bit is communicated when the actual resistance values at the sender's side and the receiver's side differ. Then the second order equation yields the two resistance values but the eavesdropper is unable to determine the actual locations of the resistors and to find out the state of the sender's bit. The receiver knows that the sender has the inverse of his bit, similarly to quantum entanglement. The eavesdropper can decode the message if, for each bits, she inject current in the wire and measures the voltage change and the current changes in the two directions. However, in this way she gets discovered by the very first bit she decodes. Instead of thermal noise, proper external noise generators should be used when the communication is not aimed to be stealth.Comment: Physics Letters A, in press; Manuscript featured by Science, vol. 309, p. 2148 (2005, September 30

Long Response to Scheuer-Yariv: "A Classical Key-Distribution System based on Johnson (like) noise - How Secure?", physics/0601022

This is the longer (partially unpublished) version of response; the shorter version (http://arxiv.org/abs/physics/0605013) is published in Physics Letters A. We point out that the claims in the comment-paper of Scheuer and Yariv are either irrelevant or incorrect. We first clarify what the security of a physically secure layer means. The idealized Kirchoff-loop-Johnson-like-noise (KLJN) scheme is totally secure therefore it is more secure than idealized quantum communication schemes which can never be totally secure because of the inherent noise processes in those communication schemes and the statistical nature of eavesdropper detection based on error statistics. On the other hand, with sufficient resources, a practical/non-ideal realization of the KLJN cipher can arbitrarily approach the idealized limit and outperform even the idealized quantum communicator schemes because the non-ideality-effects are determined and controlled by the design. The cable resistance issue analyzed by Scheuer and Yariv is a good example for that because the eavesdropper has insufficient time window to build a sufficient statistics and the actual information leak can be designed. We show that Scheuer's and Yariv's numerical result of 1% voltage drop supports higher security than that of quantum communicators. Moreover, choosing thicker or shorter wires can arbitrarily reduce this voltage drop further; the same conclusion holds even according to the equations of Scheuer and Yariv.Comment: The older long response and the newer brief response (in press, PLA) with modelling data are fuse

Noise-based logic: Binary, multi-valued, or fuzzy, with optional superposition of logic states

A new type of deterministic (non-probabilistic) computer logic system inspired by the stochasticity of brain signals is shown. The distinct values are represented by independent stochastic processes: independent voltage (or current) noises. The orthogonality of these processes provides a natural way to construct binary or multi-valued logic circuitry with arbitrary number N of logic values by using analog circuitry. Moreover, the logic values on a single wire can be made a (weighted) superposition of the N distinct logic values. Fuzzy logic is also naturally represented by a two-component superposition within the binary case (N=2). Error propagation and accumulation are suppressed. Other relevant advantages are reduced energy dissipation and leakage current problems, and robustness against circuit noise and background noises such as 1/f, Johnson, shot and crosstalk noise. Variability problems are also nonexistent because the logic value is an AC signal. A similar logic system can be built with orthogonal sinusoidal signals (different frequency or orthogonal phase) however that has an extra 1/N type slowdown compared to the noise-based logic system with increasing number of N furthermore it is less robust against time delay effects than the noise-based counterpart.Comment: Accepted for publication by Physics Letters A, on December 23, 200

Computation using Noise-based Logic: Efficient String Verification over a Slow Communication Channel

Utilizing the hyperspace of noise-based logic, we show two string verification methods with low communication complexity. One of them is based on continuum noise-based logic. The other one utilizes noise-based logic with random telegraph signals where a mathematical analysis of the error probability is also given. The last operation can also be interpreted as computing universal hash functions with noise-based logic and using them for string comparison. To find out with 10^-25 error probability that two strings with arbitrary length are different (this value is similar to the error probability of an idealistic gate in today's computer) Alice and Bob need to compare only 83 bits of the noise-based hyperspace.Comment: Accepted for publication in European Journal of Physics B (November 10, 2010