A consortium of companies has published a set of security practices they want all web authentication authorities to follow for their secure sockets layer certificates to be trusted by browsers and other software.
The baseline requirements (PDF), published this week by the Certification Authority/Browser Forum, are designed to prevent security breaches that compromise the tangled web of trust that forms the underpinning of the SSL certificate system. Its release follows years of mismanagement by individual certificate authorities permitted to issue credentials that are trusted by web browsers. Most notable is this year's breach of DigiNotar, which led to the issuance of a fraudulent certificate used to snoop on 300,000 Gmail users in Iran.
The four dozen or so members of the CAB Forum still have a way to go, since their requirements are meaningless unless they are mandated by the software makers who place their trust in the authorities.
And it's not yet clear that will come to pass. Of the five browser makers queried for this article, only Opera has committed to make compliance with the requirements a condition for including an authority's root certificate in its software. A Mozilla official, meanwhile, said only that the requirements would be discussed among developers in online forums.
A Microsoft statement said the company "will work with the industry Auditors and Certificate authorities to get the new guidelines factored into the Microsoft Root Program." Company representatives didn't respond to an email asking what that means. A Google spokesman said Chrome trusts whatever CAs are trusted by the underlying operating system. Representatives from Apple didn't respond to emails seeking comment.
As the terms suggest, the baseline requirements would serve as a set of industry practices each CA would be required to follow to remain in good standing. Among other things, they would require them to “develop, implement, and maintain a security plan” to prevent the types of breaches that hit DigiNotar. The guidelines also mandate the reporting of breaches and the revocation of any fraudulently issued certificates that resulted, and require the use of certificates with RSA signing keys of 1024 bits or higher.
As useful as each requirement is, this week's release only underscores how hopelessly broken the SSL system is. With some 650 entities around the world authorized to issue certificates trusted by Internet Explorer, Chrome, Firefox, and other browsers, all it takes is the incompetence or malfeasance of one of them to bring the entire system down. Even if the requirements become a condition adopted by all browser makers, it's not clear they have the will or the ability to adequately enforce the measures.
With the cracks in the net's foundation of trust too big to ignore, a variety of alternatives are competing for attention. Among the most appealing is the Convergence project devised by security researcher Moxie Marlinspike, which relies on a loose confederation of notaries that independently vouch for the authenticity of a given SSL certificate.
In addition to removing trust in an unwieldy number of CAs, this crowd-sourcing approach has huge privacy benefits, since notaries are intentionally kept in the dark about what sites a given IP address is accessing. Under the current SSL system, CAs get to log
each multiple visits an IP address makes to HTTPS pages protected by one of their certificates.
Other alternatives include a plan Google researchers published late last month. It would require all CAs to publicly disclose the cryptographic details of every certificate they issue so the credentials can be publicly verified. The proposal, which is in many respects similar to an alternative recommended by the Electronic Frontier Foundation, has already been criticized by some CAs, who object to publishing what they consider to be proprietary information.
With banks, merchants, and millions of other organizations using the SSL certificates to prove they're the rightful owners of websites, and to encrypt data passing between their servers and end users, it's hard to overstate the system's importance. This week's requirements probably won't hurt, but it's doubtful they'll do much to fix the structural flaws that put us all at risk. ®