Image Number 7 for United States Patent #6397328.
A method for verifying that the expected components of a postage metering system includes alternate embodiments for verifying a PSD coupled to a host system is the expected PSD. The method further includes verifying the host system as the expected host system. A first message is encrypted in the PSD using a first cryptographic key to obtain a first encrypted message. The first encrypted message is sent to the host system which decrypts the first encrypted message using a second cryptographic key. The host system then encrypts a second message derived from the decrypted first encrypted message using the second cryptographic key. The host system then sends the encrypted second message to the PSD which decrypts the second encrypted message in the PSD using the first cryptographic key. The PSD compares the decrypted second encrypted message with the first message, and activates the PSD for processing transactions requested by the host system when the decrypted second encrypted message corresponds to the first message.