secure links using classical (i.e., non-quantum) physics

Steven M. Bellovin smb at cs.columbia.edu
Sat Dec 10 10:08:55 EST 2005


http://arxiv.org/abs/physics/0509136

Totally Secure Classical Communication Utilizing Johnson (-like) Noise 
and Kirchoff's Law
Authors: Laszlo B. Kish
Comments: 14 pages; Google search terms: +totally +secure +communication
Subj-class: General Physics
Journal-ref: Manuscript featured by Science, vol. 309, p. 2148 (2005, 
September 30)

    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.

		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb



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