Factors of Encrpytion Strength
Now, let's talk about encryption strength. There are two main factors contributing to your encryption strength: Your certificate's private key (also referred to as a key pair, or just key) and your server's configuration.
When it comes to your private key, you have two main choices: RSA or ECC (Elliptic Curve). RSA is a system that has been around for decades and is very reliable and widely supported by servers and browsers. When you see "2048-bit keys," that's referring to RSA. If you are not sure what you need, RSA is a safe default choice, and all SSL certificate products support it.
ECC is a newer technology that sits at the cutting edge of encryption strength and speed. If you are chasing the ultimate in performance, ECC is the choice for you. Support for ECC may not be available if you are running an older web server (notably, Windows Server 2003 or older, or a version of Apache earlier than 2.2.26). But on the client side, support should not be a problem, unless you have a large number of users on Windows XP. Not every SSL certificate we sell supports ECC keys, so not every SSL certificate we sell supports ECC keys, so keep that in mind when picking your certificate.