DigiNotar filed for bankruptcy in a Netherland court on Monday, and its assets will be liquidated by a court-appointed trustee, said Vasco Data Security International, the Chicago company that purchased DigiNotar last January for $13.1 million.

"Effective as of the beginning of business today, the Trustee has taken over the management of DigiNotar's business activities," Vasco said in a statement on Tuesday.

In late August, DigiNotar admitted that hackers had illegally generated numerous SSL (secure socket layer) certificates, including one for google.com that was later found to have been used to through their Gmail accounts.

that it had first discovered the intrusion on July 19, but had not disclosed the breach to browser makers, the Dutch government -- which used DigiNotar certificates to validate the identities of many of its websites -- or other customers until more than a month later.

An investigation sponsored by the Dutch government revealed that the hacker or hackers first compromised DigiNotar's servers in mid-June and made off with more than 500 certificates.