Can not clone any git repository from github

I recently (Jul 2014) had a similar issue and found on OS X (10.9.4) that there was a "DigiCert High Assurance EV Root CA" certificate had expired (although I had another unexpired one as well).

1. Open Keychain Access
2. search Certificates for "DigiCert"
3. View menu > Show Expired Certificates

I found two certificates named "DigiCert High Assurance EV Root CA", one expiring Nov 2031 and the expired one at July 2014 (a few of days previously). Deleting the expired certificate resolved the issue for me.

Hope this helps.

I fixed my problem by checking my Keychain (Application -> Utilities -> Keychain Access.app)

I figured out that I had a own Digicert Certificate in my loging Keychain. It looks like this was broken. I have removed it and after this everything works fine.

Now https://github.com has a green "button" in the url bar instead of an grey one.