Re: unintended consequences?
Does that mean that the new fiber is less tappable? Somehow, I suspect that Corning and the relevant authorities have been in touch to work out any problems. Corning is a politically very well connected company. Amory Houghton, a member of the family that has controlled the company since its founding in 1851, was company CEO from 1965-84, and was then the member of Congress from my district from 1986-2005. His father was CEO and later ambassador to France. His grandfather was CEO and later member of Congress and then ambassador to first Germany and later Britain. You get the idea. R's, John - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to [EMAIL PROTECTED]
unintended consequences?
I recently saw a news story about a new kind of fiber optic cable from Corning -- it has a much smaller bending radius. (See http://money.cnn.com/magazines/fortune/fortune_archive/2007/08/06/100141306/index.htm?postversion=2007072303 and http://www.corning.com/media_center/press_releases/2007/2007072301.aspx) The problem is that when fiber is bent too sharply, the light escapes. Of course, that's the rumored way that, umm, agencies tap fiber: they bend it enough that some light escapes, but not too much. That trick won't work nearly as well with the new fiber, which is reportedly 100x more bendable. Does that mean that the new fiber is less tappable? --Steve Bellovin, http://www.cs.columbia.edu/~smb - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to [EMAIL PROTECTED]
Re: unintended consequences?
Steven M. Bellovin wrote: Does that mean that the new fiber is less tappable? No change, notwithstanding anecdotal references on fiber bending as used for tapping. Tapping a fiber can be done without much notice by matching the index of refraction outside the outer fiber layer, after abrasion and etching to reach that layer. There is no need for bending, which might not be physically possible (eg, in a thick cable bundle), would increase propagation losses beyond that caused by the tapped signal power itself, and might create detectable backward propagating waves (BPWs are monitored to detect fiber breach). Low-loss taps are essential. A tap must extract a portion of the through-signal. This, however, should not have the effect of significantly reducing the level of the remaining signal. For example, if one-quarter of the incident signal is extracted, then there is a 1.25 db loss in the remaining through-signal, which can easily be detected. Cheers, Ed Gerck - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to [EMAIL PROTECTED]
