Patent ID: 6397328
Filing Date: 2002-05-28
Classification: G06Q,G07B,H04L

Abstract:
A method verifying that a host system and a postage security device (PSD) coupled thereto are authorized to dispense postal value, the method comprising the steps of:verifying that the PSD is the expected PSD; encrypting a first message in the PSD using a first cryptographic key to obtain a first encrypted message; sending the first encrypted message to the host system; decrypting the first encrypted message in the host system using a second cryptographic key; encrypting in the host system a second message derived from the decrypted first encrypted message using the second cryptographic key to obtain a second encrypted message; sending the encrypted second message to the PSD; decrypting the second encrypted message in the PSD using the first cryptographic key; comparing the decrypted second encrypted message with the first message; and activating the PSD for processing transactions requested by the host system when the decrypted second encrypted message corresponds to the first message, wherein the step of verifying that the PSD is the expected PSD comprises the steps of: generating a third message in the host system, said third message including at least first transaction dependent data from a first transaction record stored in the host system during the last transaction between the host system and the PSD, said first transaction dependent data changing for each transaction between the host system and any PSD; encrypting the third message with an encryption key stored in the host system; sending the encrypted third message to the PSD; decrypting the encrypted third message with a decryption key stored in the PSD to obtain the first transaction dependent data; and comparing in the PSD the first transaction dependent data to second transaction dependent data from a second transaction record stored in the PSD, said second transaction dependent data changing for each transaction between any host system and the PSD.