Small addendum on that, DigiNotar was one of the
four CA's handing out "PKIoverheid" certificates, so certificates for governmental purposes. See this archived copy of the FAQ (in Dutch) after the DigiNotar breach, specifically the question "Hoe weet de overheid dat certificaten van de 3 andere bedrijven in Nederland die PKI-overheidscertificaten uitgeven wel betrouwbaar zijn?":
https://web.archive.org/web/20111019224308/http://www.rijkso...