[Cryptography] IDs and licenses, not Possible reason why password usage rules

[John Levine]

In article <66f70bd6-4b3d-1b64-8ab1-93137186097d at symas.com> you write:
>John Levine wrote:
>> In article <69b8ae4f-962c-a1d6-9532-99bef1a8a1db at symas.com> you write:
>>> This one is easy - you can't travel with an expired photo ID because the possibility
>>> exists that someone else is already traveling with the valid ID.
>> 
>> Assuming the someone else isn't your identical twin, could you explain
>> in more detail how that works? ...

>An expired photo ID has to be considered the same as a forged ID or a
>counterfeit, because there's a high probability that the corresponding
>new/renewed ID exists and is in circulation.

I'm sorry, but this assertion bears no relation to any ID system with
which I am familiar.

I have an envelope full of old driver's licenses and passports.  My
previous license and my current one look identical other than the
dates, since the state used the same picture.  Why does one identify
me and the other doesn't?  Same person, same picture, same issuer.
Same proof that I'm old enough to buy beer, or that my name matches
the one on a plane ticket.

>IDs have to be unique.

I think we mean radically different things by "ID" and you are confusing
an ID with a license.

If you are saying that I can only have one valid driver's license or
one passport at a time, that is sort of true.  People can sometimes
have two passports from the same issuer, and the world has not ended.

If the question is "is John allowed to operate an automobile?" the
license number is a key to the state's database, which someone
(typically a policeman) can check to see that it's not suspended or
revoked.  That's not an ID, it's a license.

If the question is "is this John who claims to be 65 years old" and I
look like the somewhat younger guy in the picture, it's an ID and the
license number and expiration date is irrelevant.  It's identified me.

R's,
John