SSL acceleration is a technique that off-loads the processor intensive public key encryption algorithms used in SSL transactions to a hardware accelerator. These solutions often involve a considerable up front investment as the specialized equipment is rather costly. o3 Magazine though looks at using off the shelf server hardware and open source software to build a cost effective SSL accelerator.
Ultimately there are two ways to do SSL Acceleration or SSL off-load. It can be done on the server side by installing an SSL Accelerator card, which has special custom processors designed to perform the public key encryption algorithms in hardware rather than software.
The other way to do SSL acceleration is to install a device in front of the web servers, this is typically an appliance or switch with comparable hardware to the SSL accelerator card. These devices often provide other features such as load balancing. They typically have higher transactions per second and thruputcapacity than a single server with an SSL accelerator card.
The Open Source SSL Accelerator requires a dedicated server running Linux. A multi-core or multi-processor system is highly recommended, with an emphasis on processing power and to a lesser degree RAM. The only software requirement is Nginx (Engine-X) which is an Open Source web server project. Nginx is designed to handle a large number of transactions per second, and has very well designed I/O subsystem code, which is what gives it a serious advantage over other options such as Lighttpd and Apache.
os Magazine has concluded that Nginx once again has shown that it is a versatile open source project. For the cost of a server and a few hours work, any system administrator can increase the capacity of their existing server farm by building an Open Source SSL Accelerator. Reducing the complexity of certificate management, reducing the number of certificates needed and reducing the overall load per request on the existing server farm, this solution offers a cost-effective way of breathing new life into an existing server farm.
Source: Open Source SSL Acceleration