Vasco Data said its Dutch subsidiary, DigiNotar, filed for bankruptcy following July hacker attacks linked to the Iranian government and others.
Vasco Data said its other Internet security businesses aren't affected by the filing.
We are saddened by this action and the circumstances that necessitated it, CEO T. Kendall Hunt said in a statement. Vasco Data is based in Oakbrook Terrace, Ill.
Under Dutch law, DigiNotar's bankruptcy means it will be liquidated.
In July, DigiNotar had reported evidence it had verified Iranian Internet addresses which may have allowed Tehran to spy on individual Google e-mail accounts. Opta, the Dutch data protection agency, reported the Vasco Data unit had used passwords that were too weak and could be easily breached.
Opta also told the Dutch government Web sites maintained by the CIA, as well as mail accounts maintained by Microsoft and Facebook, may have issued phony data certificates issued by DigiNotar.
Faith in digital communications traffic has been harmed, said Dutch Internal Affairs Minister Piet Hein Donner said during parliamentary debate about the hacking.
In response, Royal KPN, which is the main Dutch telephone service, reported orders for Website security certificates had increased. Rotal KPN did not report hacking attacks.
Vasco Data shares were at $5.35, unchanged in early Tuesday trading. The company's market capitalization is $203 million.