Note: Descriptions are shown in the official language in which they were submitted.
CA 02221670 1997-11-20
E-570
METHOD FOR VERIFYING THE EXPECTED POSTAGE SECURITY
DEVICE IN A HOST SYSTEM
Field of the Invention
The present invention relates generally to a system and method for
postage metering security and, more particularly, to systems and methods for
verifying authorized postal security devices.
Backqround of the Invention
The Information-Based Indicia Program (IBIP) is a distributed trusted
system proposed by the United States Postal Service (USPS). The IBIP is
expected to support new methods of applying postage in addition to, and
eventually in lieu of, the current approach, which typically relies on a postagemeter to mechanically print indicia on mailpieces. The IBIP requires printing
large, high density, two dimensional (2-D) bar codes on mailpieces. The
Postal Service expects the IBIP to provide cost-effective assurance of
postage payment for each mailpiece processed.
The USPS has published draft specifications for the IBIP. The
INFORMATION BASED INDICIA PROGRAM (IBIP) INDICIUM
SPECIFICATION, dated June 13, 1996, defines the proposed requirements
for a new indicium that will be applied to mail being processed using the IBIP.
The INFORMATION BASED INDICIA PROGRAM POSTAL SECURITY
DEVICE SPECIFICATION, dated June 13, 1996, defines the proposed
requirements for a Postal Security Device (PSD) that will provide security
services to support the creation of a new "information based" postage
postmark or indicium that will be applied to mail being processed using the
IBIP. The INFORMATION BASED INDICIA PROGRAM HOST SYSTEM
SPECIFICATION, dated October 9, 1996, defines the proposed requirements
for a host system element of the IBIP. The specifications are collectively
referred to herein as the "IBIP Specifications". The IBIP includes interfacing
~ user (customer), postal and vendor infrastructures which are the system
elements of the program.
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The user infrastructure, which resides at the user's site, comprises a
postal security device (PSD) coupled to a host system. The PSD is a secure
processor-based accounting device that dispenses and accounts for postal
value stored therein. The host system may be a personal computer (PC) or a
5 meter-based host processor. Among the various requirements set forth in the
Host System Specification is that the host system verifies that the coupled
PSD is "the expected PSD". Conventional postage metering devices and
recent digital metering devices, such as PostPerfect and Personal Post
Office, both manufactured by the assignee of the present invention, do not
10 include such verification. Thus, a method for achieving such verification is
desired.
U.S. Patent No. 5,510,992 discloses a method whereby the host PC
verifies that a storage means that is coupled to the host PC and has postal
value stored therein, is authorized for use with the host PC. The method
15 comprises the steps of storing a unique identifier, such as a serial number, in
the storage means when the storage means is filled with postal value, and
sending the unique identifier to the host PC when postage value is requested
for dispensing. The host PC then verifies that the storage means is
authorized for use with the host PC by confirming that the unique identifier
20 retrieved from the storage device is the same as one stored in the host PC.
Although such method verifies that the storage means is the expected
storage device, the storage means is not a PSD because it is not a
processor-based accounting device that dispenses and accounts for postal
value stored therein. Furthermore, the verification of the serial number in the
25 host PC is subject to fraud.
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Summary of the Invention
It has been found that the present invention provides a more secure
and reliable system and method for verifying the expected PSD is coupled to
5 the host PC. It has further been found that the present invention provides a
secure and reliable system and method for verifying the expected host PC is
coupled to the PSD.
The present invention provides a secure and reliable method for
verifying in the host system that the expected PSD is coupled to the host
10 system. In accordance with the present invention, a message, such as a
random number, is generated in the Host system and sent to the PSD. In one
embodiment, the PSD encrypts the number and transmits it to the Host
system. The Host system decrypts the encrypted number and ensures it
corresponds with the number originally generated and transmitted to the
15 PSD. In an alternate embodiment, the random number is signed in the PSD.
The signed number is transmitted to the Host where the signature is verified.
The generated message may include data indicating status of the PSD
based, for example a checksum of PSD transaction records stored in the host
system. Methods for verifying in a PSD that the expected host is coupled to
20 the PSD mirrors the two embodiments for verifying the expected PSD.
Description of the Drawinqs
The above and other objects and advantages of the present invention
will be apparent upon consideration of the following detailed description,
taken in conjunction with accompanying drawings, in which like reference
25 characters refer to like parts throughout, and in which:
Fig. 1 is a block diagram of a postage metering system in accordance
with the present invention showing a process for storing keys in a host
system and a PSD coupled thereto;
Fig. 2 is a flow chart showing an alternate process for storing keys in a
30 host system and a PSD coupled thereto;
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Fig. 3 is a flow chart of a preferred method for verifying the expected
PSD is coupled to the host system;
Fig. 4 is a flow chart of showing a method corresponding to that of Fig.
3 for verifying the expected host system;
Fig. 5 is a flow chart of an alternate method for verifying the expected
PSD is coupled to the host system; and
Fig. 6 is a flow chart of showing an alternate method corresponding to
that of Fig. 5 for verifying the expected host system.
Detailed Description of the Present Invention
In describing the present invention, reference is made to the drawings,
wherein there is seen system and methods for verifying the expected postal
security device in a host system and conversely verifying the expected host
system. Referring now to Fig. 1, a postage metering system, generally
designated 10, includes a Host PC 20 coupled to a PSD 30, a Data Center 40
15 and a manufacturer 50. The manufacturer 50 initializes PSD 30 with an
identification number, such as PSD ID 321 and a cryptographic key, such as
PSD private key 34. The manufacturer 50 also sends the PSD ID 32 and a
cryptographic key corresponding to the key in the PSD 30, such as PSD
public key 36, to the Data Center 40. The Data Center 40 then sends the
20 PSD ID 32 and the public key 36, to the Host PC 20. For the purpose of
describing the present invention, the PSD private and public keys are stored
in PSD 30 and Host PC 20 respectively. It will be understood that a secret
key shared by the Host PC and the PSD may be used in place of such key
pair.
The Host PC 20 and PSD 30 each include a microprocessor and
memory (not shown). The Host PC 20 further includes a message generator
22 for generating a message. The message may be a random number or
may include data indicating status of the PSD, for example a checksum 24 of
PSD transaction records stored a log files in Host PC 20. For the following
30 description of the present invention checksums will be used. The PSD
records stored in Host PC 20 correspond to PSD records stored in PSD 30
for each transaction by PSD 30. For a more detailed description of such
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storage of PSD records see Canadian Patent Application Serial Number
2,193,026, filed December 16, 1996, assigned to the assignee of the present
invention, and incorporated herein by reference.
Referring now to Fig. 2, an alternate method for initializing the PSD
5 with a cryptographic key is shown. At step 100, Host PC 20 generates a
secret key or a key pair. The key or key pair is stored in Host PC 20, at step
105. Host PC 20 the sends the secret key or one of the keys of the key pair
to PSD 30, at step 110. PSD 30 stores the key received from Host PC 20, at
step 11 5.
10Referring now to Fig. 3, a method is shown for verifying in Host PC 20
that the expected PSD is coupled thereto. At step 200, the Host PC
generates a message. In accordance with the present invention, the
message may be in the form of a random number or may be a checksum of a
PSD transaction log stored in the Host PC. The Host PC, at step 205, sends
15the message to the PSD. If a checksum has been sent, the at step 210, the
PSD compares the message received with a checksum of a PSD transaction
log stored in the PSD. If the checksum received is not the same as the
checksum of the PSD transaction log, then an error is flagged, at step 215,
indicating that there is a discrepancy between the PSD logs stored in the
20Host PC and the PSD. If the checksums are the same or if the message is a
random number, at step 220, the PSD signs the message with the PSD
private key. At step 225, the PSD sends the signed message to the Host PC.
At step 230, the Host PC verifies the signature using the PSD public
key stored in the Host PC. If the signature is not verified at step 2351 the
25Host PC rejects the PSD from processing any further transactions, at step
240. If the signature is verified, at step 245, the expected PSD has been
verified and the Host PC can begin request postal value from the PSD. It will
be understood by those skilled in the art that other cryptographic processing,
such as encryption or hashing may be used in place of signing.
30Referring now to Fig. 4, it may be required that in addition to the Host
PC verifying the expected PSD, the PSD verify that the expected Host PC is
coupled to the PSD. In the preferred embodiment of the present invention,
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such verification of the expected Host PC mirrors the process for verifying the
expected PSD as set forth above.
At step 300, the PSD generates a message. In accordance with the
present invention, the message may be in the form of a random number or
may be a checksum of a PSD transaction log stored in the PSD. The PSD, at
step 305, sends the message to the Host PC. If a checksum has been sent,
the at step 310, the Host PC compares the message received with a
checksum of a PSD transaction log stored in the Host PC. If the checksum
received is not the same as the checksum of the PSD transaction log, then an
10 error is flagged, at step 315, indicating that there is a discrepancy betweenthe PSD logs stored in the PSD and the Host PC. If the checksums are the
same or if the message is a random number, at step 320, the Host PC signs
the message with the Host PC private key. At step 325, the Host PC sends
the signed message to the PSD.
At step 330, the PSD verifies the signature using the Host PC public
key stored in the PSD. If the signature is not verified at step 335, the PSD
rejects the Host PC from processing any further transactions, at step 340. If
the signature is verified, at step 345, the expected Host PC has been verified
and the PSDis ready to accept transaction requests from the Host PC.
Referring now to Fig. 5, an alternate method for verifying the expected
PSD is shown. At step 400, the Host PC generates a message, such as a
random number or a checksum of a PSD transaction log stored in the Host
PC. The Host PC encrypts the message with the PSD public Key, at step
405, and sends the message to the PSD, at step 410. At step 415, the PSD
25 decrypts the encrypted message received. If a checksum has been sent
then, at step 420, the PSD compares the message received with a checksum
of a PSD transaction log stored in the PSD. If the checksum received is not
the same as the checksum of the PSD transaction log, then an error is
flagged, at step 425, indicating that there is a discrepancy between the PSD
30 logs stored in the Host PC and the PSD. If the checksums are the same or if
the message is a random number, at step 430, the PSD sends the decrypted
message to the Host PC.
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At step 435, the Host PC verifies that the message received from the
PSDis the same as the message generated in the Host PC. If not the same
at step 440, the Host PC rejects the PSD from processing any further
transactions, at step 445. If the message received from the PSD is the same
5as the message generated in the Host PC, at step 450, the expected PSD
has been verified and the Host PC can begin request postal value from the
PSD.
Referring now to Fig. 6, an alternate method for the PSD verifying that
the expected Host PC is coupled to the PSD is shown which mirrors the
10process for verifying the expected PSD as shown in Fig. 5.
At step 500, the PSD generates a message, such as a random number
or a checksum of a PSD transaction log stored in the PSD. The PSD
encrypts the message with the Host PC public Key, at step 505, and sends
the message to the Host PC, at step 510. At step 515, the Host PC decrypts
15the encrypted message received. If a checksum has been sent then, at step
520, the Host PC compares the message received with a checksum of a PSD
transaction log stored in the Host PC. If the checksum received is not the
same as the checksum of the PSD transaction log, then an error is flagged, at
step 525, indicating that there is a discrepancy between the PSD logs stored
20in the PSD and the Host PC. If the checksums are the same or if the
message is a random number, at step 530, the Host PC sends the decrypted
message to the PSD.
At step 535, the PSD verifies that the message received from the Host
PC is the same as the message generated in the PSD. If not the same at
25step 540, the PSD rejects the Host PC from processing any further
transactions, at step 545. If the message received from the Host PC is the
same as the message generated in the PSD, at step 550, the expected Host
PC has been verified and the PSD can begin to accept requests for postal
value from the Host PC.
30It has been found that the present invention is suitable for use with any
security device that is coupled to a host system in an unsecured manner. For
example, the present invention could be used for a certificate metering
system such as disclosed in Canadian Patent Application Serial No.
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2,183,274, filed August 14, 1996, assigned to the assignee of the present
invention, and incorporated herein by reference.
While the present invention has been disclosed and described with
reference to specific embodiments thereof, it will be apparent, as noted
above, that variations and modifications may be made therein. It is, thus,
intended in the following claims to cover each variation and modification,
including a certificate metering system, that falls within the true spirit and
scope of the present invention.
