1.  Field of the Invention
This invention relates generally to a system and method for providing a secure wireless communications link between a server and an entity and, more particularly, to a system and method for confirming the identity of a server used in a vehicle based wireless communications system before the vehicle will perform a function requested by the server. 
2.  Discussion of the Related Art
Communications systems are known in the art that allow a central service center to communicate wirelessly with a vehicle to provide various services, such as unlocking the vehicle door, updating the software in the various ECUs within the vehicle, etc.  The central service center will include a server that wirelessly communicates with the vehicle using designated frequency channels through one or more of cellular based communications links, land-lines, satellite communications links and the internet. 
Telematic services for these types of wireless vehicle communications systems can be classified into two categories, particularly vehicle initiated services and server initiated services.  Vehicle initiated services, such as air bag notification, route direction, etc.,  require the vehicle to call the service center.  Server initiated services, such as remote door unlock, wireless software download, etc.,  require the server to call the vehicle.  For the vehicle to call the service center and the service center to call the vehicle, each side needs to have the others phone number.  Typically, the service center phone number is programmed into the vehicle's ECU using a secure method, for example, physically installed during vehicle manufacturer. 
Server initiated services are critical functions and require a high degree of confidence in the server identity before the vehicle can accept the service request.  A hacker may wish to intentionally cause the vehicle system or manufacture harm for one reason or another, and may attempt to illicitly contact the vehicle to download a software virus to the vehicle, or other nefarious purposes.  Therefore, it is desirable to provide a security system so that the identity of a server can be confirmed before the vehicle accepts a server request. 
The current technique is to authenticate the server identity using cryptography, i.e., encoding the server request when it is transmitted, which is decoded by the vehicle.  While cryptography provides good solutions for authentification, these solutions are not 100% reliable.  It may be possible for a hacker to call the vehicle and masquerade as an authorized server if the hacker has the appropriate tools and time.