GlobalSign digital certificates have come under scrutiny after a hacker's claim that he broke into the company's computer systems. If true, it would be the second such compromise in the past few weeks.
The hacker, known as Comodohacker, announced earlier in the week that he had broken into Dutch certificate authority (CA) DigiNotar and that he had access to four other such companies, including GlobalSign, a certificate authority based in Portsmouth, New Hampshire. On Tuesday, GlobalSign said it was investigating the claim and had "decided to temporarily cease issuance of all certificates until the investigation is complete."
"We will post updates as frequently as possible," the company said in a post to its website. "We apologise for any inconvenience."
GlobalSign couldn't immediately be reached for comment, but earlier in the day, Steve Roylance, GlobalSign's business development director, said his company was "taking this very seriously."
Comodohacker, also known as Ich Sun, is the person who claimed earlier this year to have broken into security vendor and certificate issuer Comodo. At the time he said he was a 21-year-old student who had also compromised another certificate authority, but he didn't name his other victim.
Little noticed by most web surfers, digital certificates are an important part of the internet's foundations. They help browsers know when they are visiting legitimate websites rather than fakes.
A country that has control over its internet service providers and has access to fake digital certificates could create a website that would be almost impossible to distinguish from, for example, Gmail.com. That's what some experts think happened in Iran last month.
A forensics report commissioned by DigiNotar found someone had hacked into DigiNotar and set up a fake Google.com site that was used in late July and August to spy on as many as 300,000 Iranians.
Most browsers no longer trust the DigiNotar certificates, but if Comodohacker's claims are true there could be further problems in store.