[Cryptography] Smart electricity meters can be dangerously insecure, warns expert

[Ray Dillinger]

On 01/01/2017 06:22 PM, Peter Gutmann wrote:

> Radio?  Here it's done via ripple signalling, the tech goes back to (at least)
> the 1940s or 1950s and uses huge (compared to a modern MCB) electromechanical
> switches.  It was also used to turn street lights on and off.

I thought ripple signalling was used for streetlights everywhere, up
to the advent of LED streetlights at least.

If you're standing in the right place when rippled streetlights go
on, you can just barely see that they're coming on in a row, at
increments something like 1/20 second apart due to ripple signalling.
I thought it was that way everywhere because it's the cheapest/
easiest way to get a relatively gradual ramp-up of a power demand
that would otherwise bugger things up by coming on all at once.

Of course the new LED streetlights are using something else; they
come on all at once.  Some of them even have motion or IR sensors
and only come on when people are actually walking nearby.

				Bear

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