Thursday, October 15, 2015

SSL Certs and SHA-1 Weak Encryption

English: An example of a standard key used for...
Not too long ago, some browsers took it upon themselves to deem certain sites "authoritatively weak" due to the use of SHA-1 ciphers in the certificate chain presented by the server.  While the reasoning behind this move is sound, it is still a headache for server admins who may not have had to renew their certs yet and still have old ciphers in use.  If you find yourself in this position, it is fairly easy to resolve.  If you're not sure if this applies to you, you can check your web site at  The online tool will tell you if any of the certs in your certificate chain employ SHA-1 weak ciphers.

If you come up on the naughty list, there are two way to resolve the issue.  If it is close to your cert's expiration date, then renewing the cert will most likely fix the issue provided that your CA is using SHA-2 ciphers.  If they are not, then you will just get another cert issues with the same issue.  This is unlikely, as most CA's have been using SHA-2 ciphers for some time now.  If your expiration date is too far off to make renewing your cert feasible, simply request a reissue from your CA.

In either case, be sure to update appropriate revocation lists if necessary and most importantly, update your entire certificate chain for presentation to clients.