This excerpt taken from the VRSN 10-K filed Mar 3, 2009.
Identity and Authentication Services
The IAS business offers a variety of strong authentication methods to help enterprises deploy secure remote access and secure business applications through PKI, digital certificates, or one-time passwords. We offer a suite of Identity and Authentication products and services, including VeriSign Identity Protection service, our Fraud Detection Service, our Managed PKI service, and our Unified Authentication service. Revenues in our IAS business are derived from a one-time credential sale to the customer seeking network services and a one-time set-up fee. We also charge an annual service fee based upon the number of individual users authorized by the customer to access its network and a customer support fee.