[Cryptography] Measuring propagation times

[Sampo Syreeni]

On 2025-09-24, John Gilmore wrote:

> Ultrawideband communication devices use very carefully measured 
> propagation delays of infrequent wideband pulses, for locating peer 
> communicators in relative 3d space.  See:
>
>  https://en.wikipedia.org/wiki/Ultra-wideband

Yes. Are there then protocols already which leverage those measurements 
for light-speed bilateral privacy amplification? Especially ones which 
explicitly take into account the bandwidth and the interactivity of the 
physically optimal, distributed, often near-field resonant radio 
channel?

> This tech is starting to be built into mobile phones, watches, and 
> item tags.  I don't know if anyone is using it for security yet -- it 
> seems mostly used for locating things.  And, of course, it tells you 
> about where a peer is, but not whether they are trustworthy.

Of course not, but location interacts with trust. When something goes 
wrong, having location/distance data enables you to lay blame, and 
physically punish. Having it as part of a light-speed interactive 
protocol, with identity, might even prevent the problem from 
materializing in the first place. By deterrence.

Vingean True Names kinda reasoning, anybody?
-- 
Sampo Syreeni, aka decoy - decoy at iki.fi, http://decoy.iki.fi/front
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