Client SSL certificate failing in Safari (and what is SOSCCThisDeviceIsInCircle?)
I like to use the Keychain Access app to troubleshoot cryptographic trust issues and also find making a clean VM of OS X or at least a new user account helps to make sure I know I'm starting from a known trust chain.


Open Keychain Access
under the Keychain Access menu, select Certificate Assistant and then Evaluate a Certificate


From there you can use the SSL tool to evaluate things and start to pick apart what is failing or succeeding. Bouncing between that tool and Safari usually is worthwhile in sorting errors.