| 摘要 |
Encryption key data 61 is stored in a protected, non-volatile memory (NVM) 57 to which access is controlled. The encryption key data is only accessible for a predetermined time after the device 3 is powered on, preferably a predefined number of clock cycles after power-on. A boot loader program 41 is initiated after the portable device is powered on and the encryption key data is loaded from the protected NVM. Access to the protected NVM is disabled after a predetermined time has elapsed from power-on and the encryption key data is loaded before initiation of any external communication interface 21, 23. The encryption key data may be loaded from a protected NVM of a protected storage chip 51 and be loaded to volatile memory 33 on the device which may be provided on a processor 27 of the device. The protected storage chip may also comprise a microcontroller 53 for controlling access to the protected NVM, e.g. by enabling and disabling access to memory addresses. |
