Security Experts:

Facebook Ready to Retire SHA-1

One year after saying that certificates using the SHA-1 hash algorithm should be kept alive in older browsers, Facebook is finally ready to retire the insecure cryptographic hash function and move to stronger standards.

Last year, after security researchers revealed that collision attacks against SHA-1 are more practical and cheaper than previously believed, major browser companies announced plans to kill support for it as soon as possible. Facebook, however, was one of the large Internet companies to suggest that SHA-1 shouldn’t be retired altogether, and Twitter backed this proposal soon after.

Now, Wojciech Wojtyniak, a Production Engineer at Facebook, says that the social platform is ready to end support for SHA-1 certificates at the end of this year. The “well-documented security weaknesses for these older certificates” are the main reason for this, Wojtyniak notes.

Last year, Facebook claimed that killing SHA-1 in all major browsers would leave many unable to access their favorite websites. Many people, especially those in the poorest regions of the world, still use devices that are not capable of supporting TLS certificates beyond SHA-1, and the company suggested that killing SHA-1 certificates would have a great impact on these users.

“Fortunately, after an examination of our SHA-1 usage, we have determined that it is no longer necessary for us to maintain our remaining SHA-1 certificates. In fact, we have not been serving SHA-1 traffic since early November and there has been no measurable impact,” Wojtyniak said.

With Chrome, Firefox, and Microsoft Edge (and Internet Explorer 11) already en-route to sunset SHA-1 in the coming months, other large Internet players are making similar moves as well. Akamai recently said that it would end support for the algorithm on Dec 27, 2016.

“As a result, we are going to revoke our SHA-1 certificates. We look forward to the industry's movement toward greater use of stronger certificates like SHA-256,” Wojtyniak concluded.

This industry-wide move, however, is expected to impact many, considering that around 35% websites were still using SHA-1 as of about a month ago (based on the analysis of over 11 million publicly visible IPv4 websites). This means that, as soon as browsers, providers, and Certificate Authorities move to SHA-2, access to these websites will be disrupted.

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