Encryption is a mathematical process of coding and decoding information. The number of bits (40-bit, 56-bit, 128-bit, 256-bit) tells you the size of the key. Like a longer password, a larger key has more possible combinations. When an encrypted session is established, the encryption level is determined by the capability of the web browser, SSL certificate, web server, and client computer operating system.
Even if you wish to use a third party to process your cards, we would alsoways advise for you to have an SSL certificate as this provides the customer with more confidence to place orders on your website; knowing that ALL their personal information is secure.
An SSL certificate is needed if you wish to accept credit card on your website. However if you choose to use a third party to process and take card details tyhen you are not required to have one.