A server accelerator card (also known as an SSL card) is a Peripheral Component Interconnect (PCI) card used to generate encryption keys for secure transactions on e-commerce Web sites. When a secure transaction is initiated, the Web site's server sends its certificate, which has been provided by a certifying authority, to the client machine to verify the Web site's authenticity. After this exchange, a secret key is used to encrypt all data transferred between sender and receiver so that all personal and credit card information is protected. This process can severely overload a server resulting in fewer transactions processed per second, which means fewer sales. The server accelerator card takes over this process, thus reducing the load on the server. Server accelerator cards support a number of security protocols including Secure Sockets Layer (SSL) and Secure Electronic Transaction (SET).
The server accelerator card is installed into the PCI slot of the server. A software driver is loaded, and the server is ready to receive orders. This is much easier and more cost-effective than buying additional servers. Additional cards can be installed as the server's secure transactions increase.
There are also SSL acceleration appliances. These are external units that have server accelerator cards installed inside them. The unit is then plugged into the server. When a secure transaction is detected, the transaction is routed to the SSL acceleration unit for processing. SSL accelerator appliances can be added as needed by clustering them together.