A method and apparatus enhancing the security of an encrypted cryptographic key
by storing its key re-transforming information in a decryption store that is separate
from a cryptographic key store, which stores the encrypted cryptographic key, from
which accessing circuitry is able to access the encrypted cryptographic key. The
cryptographic key store may be a disk drive of a computer, the decryption store
may be a network access card installed in that computer or a mobile terminal coupled
to that computer, and the accessing circuitry may be the computer's controller.
Decryption of the encrypted cryptographic key is carried out in the decryption
store, as is the subsequent encryption or decryption using the decrypted cryptographic
key. The accessing circuitry communicates with the decryption store exclusively
via a predetermined interface, where the interface does not allow the accessing
circuitry access to the cryptographic key and to at least a portion of the key
re-transforming information from the decryption store. Thus, the encrypted cryptographic
key can be stored relatively insecurely; while the security of the cryptographic
key is maintained at a very high level because there is no native capability for
the computer to randomly read information from the network access card or the mobile terminal.