Defining key as "that which is required to open a lock".   So your retina
is the "key" to a retinal scanner.


On Thu, Jul 31, 2014 at 11:07 AM, Nicola Perotto <nicola@nicolaperotto.it>
wrote:

>
> On 31/07/2014 14:48, David C Brown wrote:
>
> > A genuine combination lock requires no physical
> > token to operate it.
>
> Every lock requires a key, physical or not.
> A combination lock requires also a physical interaction with the lock, th=
e
> "keyless" lock does not require interaction.*
>
> *
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