Abstract: A method of protecting an electronic device from unauthorized reprogramming, the electronic device comprising a data memory and a key memory, the method comprising loading into the key memory a predetermined public key of a cryptographic public key mechanism for verifying subsequent data items to be loaded into the data memory, the subsequent data items being signed with a corresponding private key; characterized in that the method further comprises setting a permanent identifier in the electronic device, the permanent identifier including an identifier identifying an entity authorized to reprogram the electronic device and an indicator identifying a selected one of a number of categories of public keys.

Abstract: Method of producing an electronic device comprising a data memory for storing data items and a key memory for storing at least one cryptographic key of a cryptographic public key mechanism. The method comprises the steps of loading a factory public key into the key memory; and loading factory software signed with a factory private key corresponding to the factory public key into the data memory. The method further comprises the steps of loading into the key memory a product public key different from the factory public key for verifying subsequent data items to be loaded into the data memory after delivering the electronic device to a customer the subsequent data items being signed with a corresponding product private key; and disabling the factory public key prior to delivering the electronic device to the customer.

Abstract: Method and apparatus for providing secure, controlled access to one or more functions in an electronic system which may have a plurality of functions having different access requirements. A desired function is enabled according to the result of a first authentication process which uses a public key which corresponds to the desired function, and access to the function is authorized by a second authentication process which uses a second, private session key computed as a result of a random challenge made by the system to an external entity during the first authentication process. Additional protection is also provided against passive and active wiretapper attacks, such that only an entity that has received authorization can access the system at the correct access level.

Abstract: Method and apparatus for providing secure, controlled access to one or more functions in an electronic system which may have a plurality of functions having different access requirements. A desired function is enabled according to the result of a first authentication process which uses a public key which corresponds to the desired function, and access to the function is authorized by a second authentication process which uses a second, private session key computed as a result of a random challenge made by the system to an external entity during the first authentication process. Additional protection is also provided against passive and active wiretapper attacks, such that only an entity that has received authorization can access the system at the correct access level.