[kabacha]

Real question here is: should the passport number have any expectations of privacy? It seems like such an easy thing to expose as you literally put it down on every document like hotel check ins etc. AFAIK it's not even a random number and instead it's generated from basic info like birth year/place/gender.

That being said it was a really good blog!

[rswail]

It depends where you are from. Our (Australian) passports have a "series" letter at the start and then a set of numbers. Not sure whether they are random or incremental or derived.

YMMV based on nation that issues yours.