Networks Security Question:

Digital signature : Information that is encrypted with an entity private key and is appended to a message to assure the recipient of the authenticity and integrity of the message. The digital signature proves that the message was signed by the entity that owns, or has access to, the private key or shared secret symmetric key.
smart cards : Smart cards help businesses evolve and expand their products and services in a rapidly changing global market. In addition to the well known commercial applications (banking, payments, access control, identification, ticketing and parking or toll collection), in recent years, the information age has introduced an array of security and privacy issues that have called for advanced smart card security applications (secure logon and authentication of users to PC and networks, storage of digital certificates, passwords and credentials, encryption of sensitive data, wireless communication subscriber authentication, etc.)