SECURE APPARATUS AND METHOD FOR PRINTING VALUE WITH A VALUE PRINTER

摘要

A system and method of printing value such as postage using a value meter connectable to communicate with a host terminal which includes a printer. The postage meter, sometimes referred to as a vault, includes a processor and storage and the host terminal includes a processor and storage. The printer is provided with a secure non-volatile random access storage and a processor and a key is stored in the non-volatile random Access storage. The key is changed for every print cycle so that it is impossible to print unauthorized postage on the basis of possession of the key used to print the last postage. A change of key is effected by reading the key from the non-volatile random access storage in the printer and changing the key, such as by a pseudo-random number generator, to provide a second key. The second key is stored in the non-volatile random access storage and then encrypted by an encryption scheme known to an authorized postage meter. The encrypted second key is transmitted to an authorized postage meter wherein it is decrypted pursuant to the decryption scheme known to the authorized postage meter. Print data may be securely transmitted to the host and printer by using the decrypted second key to convert the data to be printed. This is then sent to the printer where it is deconverted using the second key to recover the data to be printed.