pii.national_id_dk
A Danish CPR number appears near the word "CPR" in the free text.
What it looks at#
A DDMMYY-XXXX shaped number with a plausible date, and the word CPR within about
40 characters of it. Denmark dropped the CPR number’s mod-11 check digit in 2007 — current
numbers don’t satisfy it — so there is no checksum left to validate against, and a bare
10-digit date-shaped number is too common on its own (order numbers, reference codes) to
flag without more context.
Why it matters#
The CPR number is Denmark’s national identifier, used across healthcare, banking, tax and government services.
What to do#
High severity when it fires. Because this check requires a CPR label nearby, a bare
CPR-shaped number with no such label present will not be caught — that’s a known gap
(this gate doesn’t claim otherwise), not a false negative in the usual sense.