A method includes using a direct memory access controller, transferring first data from a memory to an input/output control circuit via a first bus and transferring the first data from the input/output control circuit to an authentication processing circuit via a second bus, without using the first bus. The method includes using the authentication processing circuit, generating authentication data based on the first data and transferring the first data from the input/output control circuit to a cryptography processing circuit via a third bus, without using the first bus. Responsive to authentication of the first data by a first CPU coupled to the first bus, the method includes using the cryptography processing circuit, decrypting the first data, and using the direct memory access controller, transferring the decrypted first data from the input/output control circuit to the memory via the first bus.