Abstract: An encryption code and at least one key are provided to a secure transmission device, via an external keying device, and stored in a volatile memory. A user code, entered via a keypad by a user, is received by the secure transmission device. An encrypted representation of the at least one key, based on the encryption code and the at least one key, is generated and stored in a non-volatile memory. Also, an encrypted representation of the encryption code and the user code, based on the user code, are generated and stored in the non-volatile memory. Upon power down of the secure transmission device, the at least one key and encryption code stored in the volatile memory are erased.