In Denmark, a CPR number (short for Det Centrale Personregister, or Central Person Register) is a unique 10-digit personal identification and social security number assigned to every resident and citizen.
Equivalent to social security information in the US I guess.
For some unknown reason, the SSN in USA is assumed to be secret. You go to the bank, say SSN=12345 and they give you a million dollars and then send the collector the the guy/gal with that number, and call it identity thief instead of bad bank security or fraud.
Here in Argentina, the DNI is assumed to be public, it appears in a lot of public documents next to your name, and on election day there is a list of all the local voters with name and DNI at the door of the pooling site. To pay a sweater in two installments you may need to present the phisical DNI card and a water or electricity bill and they photocopy all of them.
It's unique, but it encodes your birthday and sex.
There's only 500 numbers it could be, assuming someone knows those other things about you.
In any case, there are alternative systems for authorisation.
You're contradicting yourself, how can it be unique if only 1000 can be assigned per given date of birth? What if more than one thousand babies are born in the country one day?
It's Denmark, it won't have 1k babies born the same day.
It's the same in Sweden: YYYY-MM-DD-XXXX is the format for a personnummer, double the population of Denmark and there are no collisions.
There have been collisions in Sweden, but that was due to lots of immigrants coming from the middle east that did not know when they where born. So many of them picked first of January. They “solved” it by overflowing to the next days.
Completely forgot about the YYYY-01-01 case!
Thanks for correcting it :)
Immigrants who don't know their birthdate are assigned xxxx-01-01, so they have actually run out of numbers for January 1st in some years.
That format looks like it would allow for up to 10k per day. Unless one of those X's is a check digit?
They said sex is encoded in it, so it’s probably a sex digit.
edit: I was wrong. Wikipedia says, “The first digit of the sequence number encodes the century of birth (so that centenarians are distinguished from infants)”.
It also says “the last digit of the sequence number is odd for males and even for females”. What a strange system. Essentially the last three digits are two different sequences made to look like one.
That's a problem for future Denmark!
I'm not super familiar with SSN in US of A, but I think the Danish one is not has secret. Don't get me wrong, the leak is not good, but there is a limit to what you can do with it.
Targeted and real looking spam mails come to mind. Hey <NAME> with <Address> and <CPR>, you have to log in <fake government website> to verify X Y Z.
Apparently some pay day loans or similar with just CPR + name is or was a thing. But lets hope that will change now. Bonkers as CPR should be be treaded as a secret.