[Cryptography] How to crypto secure speed limit signs

Phillip Hallam-Baker phill at hallambaker.com
Wed Mar 25 18:57:23 EDT 2015

On Wed, Mar 25, 2015 at 9:22 AM, Darren Moffat <darren at nessieroo.com> wrote:
> This won't work in the UK because you need context to interpret the
> 'national speed limit' sign which is a black diagonal line on a white
> background.
> It could mean 60mph or 70mph depending on the road type.
> Then there are the places where there are no signs and you need to interpret
> the highway code to know what the limit would be: built up area, street
> lights means 30mph.
> Darren

The context information is provided by the spacing of street lights (!)

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