CloudFlare and SHA-1 Certificates

At CloudFlare, we’re dedicated to ensuring sites are not only secure, but also available to the widest audience. In the coming months, both Google’s Chrome browser and Mozilla’s Firefox browser are changing their policy with respect to certain web site certificates. We are aware of these changes, and we have modified our SSL offerings to ensure customer sites continue to be secure and available to all visitors.
Chrome (and Firefox) and SHA-1
Google will be making changes to its Chrome browser in upcoming versions to change the way they treat certain web site certificates based on their digital signature. These changes affect over 80% of websites.
As described in our blog post on CFSSL, web site certificates are organized using a chain of trust. Digital signatures are the glue that connects the certificates in the chain. Each certificate is digitally signed by its issuer using a digital signature algorithm defined by the type of key and a cryptographic hash function (such as MD5, SHA-1, SHA-256).
Starting in Chrome 39 (to be released this month, November 2014), certificates signed with a SHA-1 signature algorithm will be considered less trusted than those signed with a more modern SHA-2 algorithm. This change Continue reading
