Patent ID: 8904193

Claim:
A method for operating a security device which includes a microcontroller, a protected memory area in which a plurality of items of protection-worthy information are stored, and a unit for encrypting and/or decrypting data, the microcontroller being connected to the protected memory area via the unit, the method comprising: accessing at least one of the plurality of items of protection-worthy information by the microcontroller via the unit, wherein: the plurality of protection-worthy information include a plurality of keys of the security device, the plurality of keys including (a) at least one encryption/decryption key used for encryption or decryption of data and (b) a main key used for encryption or decryption of the at least one encryption/decryption key; and accessibility of the plurality of items of protection-worthy information by the microcontroller is only indirectly via the unit; and replacing the at least one encryption/decryption key with a new encryption/decryption key including: receiving at the microcontroller the new encryption/decryption key in encrypted form, wherein the new encryption/decryption key was encrypted using the main key; and transferring to the unit the encrypted new encryption/decryption key allowing the unit to decrypt the encrypted new encryption/decryption key to overwrite the at least one encryption/decryption key with the new encryption/decryption key.