At the free level, there’s no SSL support on CloudFlare.
At the Pro level and above, SSL is supported by CloudFlare. CloudFlare operate two levels of SSL protection – ‘Flexible’, which encrypts only the connection between the end user and CloudFlare, and ‘Full’, which encrypts the connection between CloudFlare and our hosting servers as well.
‘Full’ is the only level which is suitable for e-commerce applications, login forms and the like; the connection between CloudFlare’s servers and our hosting servers is over the public Internet and therefore cannot be considered secure. In order to use Full SSL, a website must have an SSL certificate with us, as well as SSL support enabled with CloudFlare.
At Business and Enterprise levels, CloudFlare support uploading a custom certificate, as well as using a CloudFlare-supplied one; this is particularly useful for sites that have an EV certificate. Copies of certificates and private keys can be obtained by contacting Support.