Methods and apparatus for internet based financial transactions with evidence of payment6233565Abstract A system and methods for conducting Internet based financial transactions between a client and a server. The client has a processor, a printer, a client authentication module, a module for issuing a transaction request, and a unique digital signature. The server has a network including a transaction server, a transaction database, a server authentication module, and a receipt generation module. An internet connection is used between the client and the server network. The transaction execution system includes authentication, wherein the client authentication module and the server authentication modules communicate via the internet connection and are authenticated to each other. A transaction module is included wherein, in response to the client and server being authenticated, the client issues a transaction request to the server and the transaction server, in response to a client transaction request, executes an electronic payment transaction at the server and records the transaction in the transaction database. The server receipt generation module, in response to an executed electronic payment, then generates a receipt and transmits the receipt to the client. The receipt includes the client digital signature and a data set uniquely identifying the executed transaction and is printable by the client printer. The printed receipt is an evidence of payment for the executed transaction. In addition, a third party seller having a processor and a database can be connected via a communication channel to the server, wherein the client further obtains a registration certificate representative of being a consumer registered with said third party seller. A third party credit facility also may be connected via a communication link to the server, for implementing credit card transactions. The transaction execution system may be to purchase an amount of postage, to purchase a ticket for air travel or to an entertainment complex or the like. Claims We claim: Description FIELD OF THE INVENTION
TABLE I
Transactions
Server Actions
Transaction Master Server Payment Server
Postage Server Customer Server Credit Auth.
Transaction Type Server 190 300 190 Log Server 195
450 460 Server 400
Authentication 1. Verify client 1. Provide 1. Log
Transactions Provide customer
client 2n to server Signature customer
information
2. Decrypt public key
client request 2. Send
3. Request Transaction
customer Summary to
lookup Log Server
4. Decipher
message
5. Validate
customer
6. Send
digitally
signed and
ciphered
message
Purchase of 1. Verify 1. Increment Manage 1. Log
Transactions 1. Decrement 1. Issue
Good/services e.g., digital; customer PSD Purchase 2. Send Log
to Master check request
postage Signature of ascending Process TPS (IBIP
descending 2. Receive
client register Infrastructure)
register response
2. Decrypt 2. Send
2. Request 3. Send response
client Transaction
postage from to Purchase
Request Summary to
TPS (USPS) Server
3. Send Log Server
3. Increment
purchase
Master
Request to
descending
Payment
register
Server
4. Send
4. Digitally
Transaction
Sign and
Summary to
Encrypt
Log Server
Response
5. Send
ciphered
message to
client
Refund 1. Verify client 1. Increment Manage 1. Log
Transactions 1. Decrement 1. Issue credit
Signature customer PSD Refund 2. Send Log to
TPS Provider PSD check request
2. Decrypt ascending Process (IBIP
ascending 2. Receive
client register Infrastructure)
register response
Request 2. Send
2. Send 3. Send response
3. Send Transaction
Transaction to Purchase
Request Summary to
Summary to Server
to Payment Log Server
Log Server
Server
4. Digitally
sign
and Encrypt
Response
5. Send
digitally
signed and
ciphered
message to
client
Print 1. Verify client 1. Decrement 1. Create 1. Log
Transactions
Signature customer PSD Indicia 2. Send Log to
2. Decrypt ascending 2. Create file: IBIP
client register of Indicia Infrastructure
Request 2. Send 3. Notify
3. Send Transaction Transaction
Request to Summary to Server
Payment Log Server
Server
4. Digitally
sign and
Encrypt
Response
5. Send
ciphered
message to
client
Address Change 1. Verify client 1. Log
Transactions 1. Update
Signature 2. Send Log to
Customer
2. Decrypt IBIP
Record
client Infrastructure
2. Send
Request
Transaction
3. SendRequest
Summary to
to Customer
Log Server
Server
Address Cleanse 1. Verify client 1. Log
Transactions 1. Cleanse
Signature 2. Send Log to
TPS Addresses
2. Decrypt (IBIP
2. Create file of
client Infrastructure)
addresses
Request
3. Notify
3. SendRequest
Transaction
to Customer
Server
Server
4. Send
4. Digitally
Transaction
sign and
Summary to
Encrypt
Log Server
Response
5. Send
ciphered
message
Scalability is maintained by allowing for multiple servers, particularly for the transaction 180, payment 190, and log 195 servers (multiple servers not shown). These servers will process the highest volumes of traffic because all transactions will pass through them. Preferably, various other software manufacturers will be able to develop and/or access both the printing and transaction management pieces of the system through a controlled set of Application Program Interfaces (API) for each customer 2n to operate the system using a conventional word processing or x-window motif program and the downloaded client software. Registration and Acquisition In one preferred embodiment, each customer 2n goes through a sequence of steps to ensure that the customer has been licensed and authorized to produce postage and that use of the Host system 10n can be strictly monitored. With reference to FIG. 6, one such sequence of steps include the following. At step 201, the customer 2n uses the Internet browser software and an Internet 30 to connect to the web site server 150 of RSP 4. At step 202, the customer 2n fills out a registration form, e.g., an on-line form that collects the information necessary to register/license the customer. In the preferred embodiment, the user electronically fills out a Postal Service Form 3601-A application, to enable the customer to purchase postage electronically. At step 203, the customer 2n logs off, and at step 207, the RSP's web server 150 transmits the completed application to TPS 6 (e.g., IBIP Finance Infrastructure, also called CMLS). At step 204, web server 150 creates a customer and at step 205 creates a public key and a private key pair for the customer record, and at step 206 a log of events for the customer is created. At step 208, TPS 6 returns a "license" number to Web Server 150, which recreates a customer record at step 209 and updates the record at step 210. At step 211, web server 150 generates a letter electronically, containing the customer's new Customer Number, the License Number, and a Password set. This letter is ported to a suspense file for someone to execute. The letter is then executed and delivered to the customer via regular mail. An alternate mode of conveying this customer specific information may be used, e.g., encrypted e-mail, voice or facsimile transmission. At step 212, after receiving the letter, the customer uses its Internet browser again to connect to the RSP web server 150. The customer selects a SOFTWARE DOWNLOAD option at step 213, and is prompted for the customer number and password to enter the secured area of web server 150 at step 214. Once the customer password and identification is entered and verified, at step 215 the web server 150 retrieves the previously stored customer record. At step 216, the customer then downloads the client software program for operating the system, the internet protocol address for postal transactions, the public key/private key pair for the RPS 4, and the public key for TPS 6. Using the client software, the customer's private key is encrypted using the password and stored at step 217, and then SETUP is run at step 218. SETUP extracts the client software; installs it on the client hard disk; updates the Windows.RTM. registry; and updates Word.TM. (or comparable word processing program) templates. For enhanced security, the customer then enters a new password at step 219 and reencrypts the customer public key, private key pair with the new password at step 220. Certificate During the Registration process, the web server 150 obtains and forwards the appropriate information to TPS 6, e.g., the United States Postal Service Certifying Authority for issuance of the user's certificate ("X.509") as required by Postal Service specifications. Preferably, the issuance of the Postal User Certificate X.509 from the United States Postal Service Certifying Authority will be accomplished in as near to real time as possible, because generally a postage value download to the user's PSD 20n will not be permitted without an authenticated certificate. With reference again to FIG. 3 and to FIG. 6, after receiving the certificate and a license/registration number at step 216, the user 2n can then proceed to make a purchase, e.g., of postage. User 2n makes a purchase through a proprietary connection over the Internet 30 using the appropriate IP address as provided by the downloaded client software to connect with the RSP's Internet transaction server 180, utilizing a suitable form of payment, such as credit cards, electronic funds transfer, ACH debit cards, or checks. Electronic payments are reported to the transaction server 180 which then transmits them to a specified financial institution for deposit. Upon receipt back of an authorization code, transaction server 180 then increments the user's descending register 21 in PSC 20n with the correct amount. The ascending and descending registers of each user 2n are stored on the Master Server 300 at RSP 4. Under current Postal Service guidelines, the total maximum amount permitted in the descending register 21 is $500.00, but any value could be used, as well as no limit at all. Checks used to pay for postage are preferably sent by the user 2n to a designated lockbox institution for processing in a conventional manner. When a user's check has cleared, the lockbox institution transmits an electronic authorization to the transaction server 180, which operates to transmit a notice to the user 2n of postage availability. The user 2n typically must then access the transaction server 180 to obtain the postage (which may have already been allocated to the user 2n and held in a suspense server 310) and server 180 operates the master server 300 to increment the user's descending register 21n in PSD 20n by the proper amount and clear the register in suspense server 310. In accordance with a preferred embodiment, a "pool" of postage preferably is purchased by PSP 4 from the TPS 6, i.e, United States Postal Service, and maintained in the master PSD 40 by the RSP 4. Postage is added to this pool when required (e.g., when purchased by PSP 4 or by decrementing the user's descending register 21n when the system software is uninstalled, returned, or otherwise credited), and is decremented when necessitated. Indicium One of the advantages of the present invention is that postage can be purchased and effectively downloaded to the local printer 70 of the user 2n where it is printed onto an envelope or label as a virtual postage stamp. This virtual postage stamp is referred to as an "intelligent indicia 74" or more simply "indicia 74" and is evidence of payment for the postage that is locally printed and directly applied onto envelopes or labels via a printer 70n. See FIGS. 4A and B. Indeed, envelopes and labels can be printed singly, that is one at a time, or in a batch, or in groups as from a mailing list. The Log Server 195 stores all data used for reporting, both internally to PSP 4 and to the TPS 6. The Log Server 195 also performs all audit functions. Results of these audits will be made available to TPS 6 and in the case of the postage embodiment, to various USPS agencies, as indicated in FIG. 2 as data management module 42 in PSP 4 and data management module 62 in TPS 6. As noted, the master server 300 maintains a pool of postage and its own supply of cash from which refunds are given. It is desired in the postage system embodiment that there be two types of refunds: full and partial. The refunds can be transacted by one of two methods: electronic or manual. Partial refunds are given for spoilage and similar reasons, including the destruction of downloaded indicia, typically prior to printing, due to customer hardware or client software failures. Full refunds are given to customers when the system client software is uninstalled. Electronic refunds are given when the user 2n has established an electronic payment pattern. Since the PSD 20n and all relevant customer information is maintained on the master server 300, no refunds will need to be given for failures or disk crashes in the Host system 10n. The client software portion of the system installed and resident on the hard drive in the PC of user 2n functions as the Host system 10n. The software encompasses a variety of functions, some of which are: maintenance of registration information for obtaining a user's license from the TPS 6 (postal service); printing of, e.g., a postal/service lease agreement; integration with existing word-processing applications for an API to print postage, e.g., when printing the envelope for a letter or a label for a package; processing of mailing lists; implementation of ZIP+4 address cleansing (hygiene); calculation of postage by mail-piece according to established postage rate tables; formatting of a mail-piece for proper printing; printing mail-piece on standard printers, e.g., in a Windows.TM. environment; and collection of purchase and refund request information. It is believed that it is within the abilities of a person of ordinary skill in the art to create client software instructions and APIs suitable to implement some or all of the foregoing functions as a matter of design choice. A portion of the system software resident on the transaction server 180 of RPS 4 functions as the Postal Secure Device (PSD) 20n. This software portion, known as the Transaction Manager, encompasses many features and benefits to both the TPS 6 (e.g., United States Postal Service) and customers, as illustrated by Table II.
TABLE II
Function/Feature USPS Benefit Customer Benefit
Secure purchase and Secure revenue stream Protection of postage
storage of postage purchase
Creation of authorized Fraud detection, Efficient mail
indicia improve efficiency preparation and
of mailstream application
Logging and reporting Ability to track Tracking of postage
all indicia postage purchases and costs and their
detect fraud; ability to allocation within
detect variations in company
mail flow (volume of
mail, by piece count
and weight) to
schedule sufficient
resources to collect
and deliver mail
Processing of refund Positive customer Ability to recover
requests support and cash funds lost through
management system spoils, etc.
Processing of license Ability to track Expedient processing
cancellations and postage application
revocations population
Fraud detection and Revenue protection Detect theft or misuse
postal service of product by
notification unauthorized users
The system of the present invention can be considered as a combination of several components or modules which include: UI (user interface), Security, Printing, Financial Transactions, Communications, and Database Management. Each of these is designed to be in compliance with industry standards, discussed below. UI The UI is preferably Microsoft Windows95.TM. Logo compliant although other operating systems also could be used, e.g., OS/2, WindowsNT, Macintosh, etc. To achieve this compliance, the UI may be built using Microsoft Visual C++ and MFC in accordance with Microsoft's published standards. Both screens and pop-up windows as defined by the Microsoft standard may be used. Security The system's security features will use standard, publicly available NIST-approved algorithms. These are discussed below under security, authentication and authorization. Printing Any industry standard for the creation of a two-dimensional barcode or matrix code may be used for printing data as part of the indicium 74. The preferred standard is the Data Matrix Symbolizing available from CiMatrix, Shawmut, Mass. (formerly known as International Data Matrix, Inc.). The rest of the printing functions are conventional, and do not have applicable industry standards. Financial Transactions All purchase and refund requests will be digitally signed and encrypted for transmission from the host IOn to the transaction server 180. RC2 symmetric encryption standard key pairs (public key/private key) may be used to support such encryption and decryption. RC2 will be used to protect the nature of the purchase/refund request, which may include credit card information. RC2 is a well-known industry standard. RC2 is a product of RSA. RSA is an accepted vendor for these products according to the IBIP Indicium specification dated Jun. 13, 1996. For credit card purchases/refunds the transaction from the transaction server 180 to the credit bureau 9 preferably will employ SSL3.0 (Secure Socket Layer) standard encryption for secure packaging of the transaction. SSL3.0 is an accepted industry standard for financial transactions across a TCP/IP network. Other suitable encryption standards could be used. For check payments, a standard lock-box company will be used. Communication with the lockbox company will utilize industry standards. It should be understood that other encryption and decryption algorithms and techniques now or hereinafter in existence also could be used. Communications The system requires an active connection to the Internet 30. The method for obtaining that connection is at the sole discretion of the customer. The term Internet also should be understood to include the world wide web, public and private networks and extranets supporting TCP/IP. Database The PSP 4 server 180 will store all transaction, customer, and PSD information in one or more industry standard databases, each preferably being an SQL database, using an SQL Server. This product has been adopted as an industry leader in relational database technology, although other relational database technologies could be used, as well as non-relational database technologies. Miscellaneous The software design preferably employs industry standards for both the object and database modeling. The Booch methodology may be employed to produce an industry standard object model. The James Martin methodology may be used to generate the data model. Rational Rose v4.0 can be used to capture the data for this methodology and for its output. ERWIN Data Modeler can be used to capture the data and generate the data model used by this product. Host System & Postal Security Device Features and Functions a. Registration As already described, the customer 2n may initiate a registration process by entering the web site server 150 (FIG. 3), and selecting the "Registration" option. The customer is then presented with a screen that resembles the Postal Service 3601-A license request form. This screen has entry fields for all pertinent address information (required and optional information) and graphical user interface "radio buttons" that allow the user to supply different addresses for shipping, billing, and the physical location of the PC of Host 10n within which the downloaded client software will be resident. When the initial address is entered, all four addresses are stored. For example, the fields to be filled in on the initial address screen typically include: (1) Name, (2) Company, (3) Address (2 lines), (4) City, state, zip (allows for zip+4), (5) E-mail address, (6) Post office where large mailings would typically be deposited, and (7) State and zip for that post office. Items 6 and 7 permit the Postal Service to monitor anticipated mail flow and schedule staff and resources (trucks and planes) to accommodate efficiently the anticipated flow based on the amounts of postage electronically purchased and locally printed, with knowledge of the local postal offices, pick-up and drop-off locations. The screen also may contain an area to enter an existing "meter number" if the customer has had a registered postage meter in the past. The address fields are then checked for the existence of a PO Box address based upon finding one of the following references: PO Box, PO, P.O., P.O. Box, Box, or Post Office Box and may be cleansed in a conventional manner. See, e.g., the discussion of hygiene (cleansing) in Cordery U.S. Pat. No. 5,454,038 assigned to Pitney Bowes Co. The request is then submitted to TPS (CMLS) 6. When an approved license is returned from CMLS, a letter is sent to the customer by regular mail informing it of the license number, a customer number, and a customer password. b. Software Acquisition The client software is downloaded to the customer's Host system 10n from web server 150. The download is facilitated by state-of-the-art Web technology and data compression. The download operation is secured using SSL v3.0 technology. The customer 2n enters the download area of the web site 100 and is prompted to enter the assigned customer number and customer password. These entries are checked against the customer record in the Master Database 305. If the customer number and password are valid, the download will proceed. In addition to the client software, the customer 2n will receive a public key and a private key pair file in encrypted form from the web server 150. The keys will be stored on the Host 10 in an encrypted form. The private key is decrypted by the customer password. This private key is then used by the customer 2n and the client software for creating a customer digital signature and for decryption. Since the web server 150 has the corresponding public key, (the server 150 generates the key pair provided to the registered user 2n) the server 150 can use the customer's public key to verify the user's digital signature and to encrypt the indicia 74 (or other data) for downloading to the customer 2n. c. Software Installation Using a standard Windows location selection dialog, a user can select the drive and directory location for the software, enter a new directory, or use a default location supplied by the downloaded software. After a successful installation, the customer is prompted to enter a new password to protect the Host system 10. d. Postage Value Download A function allows the user 2n to purchase postage from the PSP 4 transaction server 180. It is initiated by selecting a "Purchase Postage" screen in the client software. The screen displays the maximum postage that can be purchased, any fees associated with this purchase, which are charged by PSP 4 or TPS 6 as the case may be, and the total cost for the purchase. The customer 2n must enter an amount of postage to purchase and select a method of payment. The methods of payment are preferably shown with "radio" buttons and include credit card, ACH debit, and check. The default payment is preferably by credit card and the credit card input area is activated. The customer then initiates transmission of all of the purchase information (e.g., addresses, purchase amount, and credit/check information) via the Internet 30 to the web server 150, which passes on the transaction request to the transaction server 180. When the Submit radio button is pressed, all customer information is digitally signed and encrypted and packaged with the purchase amount. A connection over Internet 30 is established with the web server 150 and the transaction related information is then transmitted. Because the transmission has the appropriate IP address for the transaction server 180 it will be directed by web server 150 through the firewall 160 to transaction server 180, where the transaction will be executed. If a connection cannot be made with the web server 150, then control is passed to an Unable To Connect Error. When the web server 150 responds, the text message received from the server 180 is displayed in the main message area at the top of the screen of the user's Host 10n. Possible responses include Purchase Complete, Incorrect Credit Card Information, Purchase Pending, or Credit Denied. If a Purchase Complete or Pending message is received, the descending register 21 (Postage Remaining field) specifically associated with the customer 2n in the PSD 20n is updated with the new value from the transaction server 180. The actual PSD registers 20n remain on the master server 300; the Host 10 merely displays a copy of the PSD 20n register 21 values. If the connection with the web server 150 is dropped and cannot be reconnected, then control is passed to the Connection Lost Error. Typically, three (3) communication attempts will be initiated by Host 10n to reconnect with the web server 150. If the connection fails then the process is aborted. e. Credit Card Payments If payment is by credit card, the card expiration date is checked. If the customer provided credit card expiration date is earlier than the current date, control is passed to the Expiration Date Error. If credit is denied, an error message is displayed on Host 10n and the credit card information is cleared. If credit is approved, control is passed to the main screen and an appropriate message is displayed in the standard message box of Host 10. After the user fills out the entire field on the purchase screen and selects a submit radio button, the transaction server 180 immediately constructs a new purchase request object base from these field values. After the transaction server 180 receives the purchase request, it interacts with the following servers to execute the transaction: 1. Security server 315 (to verify the user's digital signature and to decrypt the transmitted file) 2. Purchase server 190 (after the purchase request object is deciphered by the transaction server 180, it passes to the purchase server) Credit card requests are transmitted to the web server 150 by the client, forwarded to the transaction server 180, and then to a payment server 190, a credit authorization server 400, and to a remote credit bureau 9 such as to First Data Merchant Services ("FDMS"). The credit authorization server 400 is responsible for connecting to the credit card bureau 9 and getting approval: A "result" code is passed back to the purchase server 190 to indicate whether the credit card has been approved or not. For example, 0 means on the credit link is down (after 3 attempts), 1 means the credit card was rejected, and 2 means the purchase is approved. f. Check Payments If payment is by check, the check number is sent to the web server 150 and purchase server 190 along with the information listed above. The response from the purchase server 190 will include a customer number. When the response is received at the Host 10n from the transaction server 180 then control is passed to the Remittance Pop-Up Window. Check purchasing is very similar to credit card purchasing. The difference is that the purchase server 190 does not need to go through the credit authorization server 400 to obtain any credit approval and typically has a suspense server 310 to enable check processing prior to issuance of postage. Because the check purchasing cannot be validated right away, the purchasing server 190 invokes the Persistence Service and Database Service to update the database record, logging the transaction and updating the descending register in the PSD object. See Logging 196; Customer PSD 200 (increment); Master PSD 40 (decrement) in FIG. 3. g. ACH Debit Card Payments ACH debit card can be provided primarily for customers that would prefer this payment modality. Prescheduled payments (or wire transfer) that would trigger purchase could be based on known volumes or peak and valley demand requirements and easily implemented. h. Refunds Customer requests for refunds can be initiated by selecting an appropriate Refund radio button. The user must select the type of refund requested: full or partial. If the user selects a partial refund, the amount of refund requested also must be entered. The amount the user enters, when added to the existing refund register, typically cannot exceed some percentage, e.g., 1%, of the current ascending register 22 for that customer. If the amount entered does exceed this amount then control is passed to the Spoilage Limit Error and the refund amount requested can then be changed. The customer then must enter in credit card, debit card, or check information so that the appropriate account can be credited or a check can be issued. The user presses the Submit button to submit the request to the web server 150 and then to the transaction server 180. For a spoilage refund, a copy of the updated descending register 22 is received from the server 180. The actual descending register 22 is updated on the server 20n. The customer user presses the Cancel button to cancel the request and return to the Help screen. A request for a full refund will result in the termination of the customer account with the third party service provider 4 and the deactivation of downloaded client software from the Host 10n. If the credit card entered does not match a credit card used for a prior postage purchase then an error message is displayed and the user must enter data for the appropriate credit card. i. Transaction Complete In each of the foregoing transactions, once a transaction is completed, transaction server 180 creates a response transaction which is digitally signed with the digital signature of the customer 2n requesting the transaction, encrypted, and sent to the Host 10n confirming the success or failure of the transaction. The host then updates its local information to reflect changes in postage available. j. Configuration A configuration feature is desired to allow the user to change the configurable settings for the Host 10n system. It is initiated by selecting a Configure screen including radio buttons for selecting the method of logging postage usage and the address cleansing method. The screen also may contain two postage threshold entry fields and a drop-down list box for selecting a printer 70n. The user 2n is required to make selections for certain settings in a conventional manner. Optionally, log postage can be selected, which the user can use for accounting purposes. Postage usage will differ from the indicium, which is always logged on the Log Server 195. The Log database 196 DB is used to track all transactions between customers and RSP 4. The central database 197 is a staging server used to create data files for transmission to TPS 6, e.g., USPS. The indicium 74 represents a unique identifier that is digitally signed for each mail piece. Logging postage usage would store a log of the address of each letter or label, the date printed, and the amount of postage for that mail piece in a log database 196. This information may or may not be unique because multiple letters could be sent to the same address on the same day. The indicium 74, however, will always be unique and digitally signed. Logging postage usage is the default. The user also will typically choose a method by which addresses will be cleansed (also referred to as hygiened) as well as the printer 70n to be used by the system. Cleansing addresses refers to the conversion of all entered addresses to a United States Postal Service standard format, including ZIP+4 prior to printing the mailing envelope or label. CD-ROM cleansing is the default, where it is done at the Host 10n. An alternative choice is to perform cleansing via the web server 150. The user can change this selection via a standard drive selection list-box. Any suitable printer 70n may be used, for example a Postscript printer or Windows-compatible printer. The Password button can be used to change the password entered during registration. There are also a number of addresses that are required by the system. These addresses are maintained by pressing the Addresses button. Other optional settings are the default amount for purchases, as well as the amount at which a low postage warning is triggered. An error is raised if either amount is greater than the maximum amount of postage allowed. k. Print Postage The print postage feature allows the user 2n to print postage onto a selected envelope or label or a series of envelopes or labels (e.g., an array of labels as exist on a preprinted label form). It is initiated by selecting the Print Postage Screen on the main screen. The screen contains a button for entering a single address and a standard file selection area for selecting a mailing list. The screen also displays radio buttons for class of mail service and the method for calculating postage. The defaults for these are first class, and fixed price (set at $.32). The user 2n must indicate whether a Single address or Multiple addresses will be printed. This is accomplished by pressing a button for a single address or by selecting a Mailing List file. A Mailing List is selected by selecting the name of the appropriate mailing list. Once a single address has been entered or a mailing list has been selected, a drop-down list box is activated and populated with the appropriate address(es). Additional information may be required such as the Class of postage by which the mail piece(s) will be shipped and the method of calculating the postage. The system may be established so that the user selects Calculate Weight, whereupon the number of sheets of paper being mailed and a paper weight (as indicated on the paper packaging (e.g., envelope, box, etc.)) are entered. A suitable application will then calculate the total weight by referring to an algorithm resident in the downloaded client software, for example, multiplying the single sheet paper weight by the number of sheets indicated. The result is then added to the weight of the packaging (e.g., an envelope) via a table look-up. The postage for that weight and class is then determined and the list of addresses is updated. All downloaded client software and tables, including postage rate tables, may be updated each time the user Host 10 connects to the web server 150. The PSP 4 also may have the current rate table available on-line to registered users 2n for a reference. In addition, all indicia 74 (i.e., for each piece of mail) shall be logged on the server 195 whenever a print request is made by a user 2n, whether the print request is for a single piece or multiple pieces for a mailing list. With respect to maintaining logs databases 196, 197 of indicia files on the transaction server 180, it is expected that the United States Postal Service will permit these files to periodically be off loaded onto tape, or otherwise transmitted periodically. See, e.g., FIG. 1A, the reference to "batch" connecting data management functions 42 and 62. If the total postage for the job exceeds the postage available then system control may be automatically passed to the Insufficient Postage Error and then to the Purchase Postage screen. Once all information is entered, the complete list of addresses and their corresponding postage will be available for review in a drop down listbox. Pressing the Change Postage button can change postage for individual entries when that entry is highlighted. Conventionally only one entry at a time can be changed. Control is passed to the Single Address Entry Pop-Up. If the postage entered for a fixed amount is less than $0.16 then control is passed to the Invalid Amount Error. Postage can be applied in fractional amounts down to three (3) decimal points. Of course, the postage amount can be adjusted as permitted by the USPS. It should be understood that the present invention may be adapted for use with any carrier service other than, or in addition to, the US Postal Service by modifications that can be made by persons of ordinary skill in the art. Preferably, the system permits the user to preview a single envelope or label by pressing a Print Preview button. This will cause the return address, the mailing address, and a bitmap of a sample indicium 74 to be displayed as it would appear printed. Pressing this button will pass control to a standard Print Preview screen. If the user wishes to print the entire list, the Print All button is selected. Pressing Print All causes a connection to be made to the web server 150 and a file of addresses sent. This file is digitally signed by the client Host 10n for the transaction server 180 to verify. On the transaction server 180, the digital signature on the file will be verified by validation (also called the security) server 315, each address will be extracted individually and the contents of that address, along with additional information, will be used to create both the human- and computer-readable parts of the indicium 74. See indicium generation 43, FIG. 1A. The postage rate table used is checked to see if it is current, and the postage amounts are recalculated if needed. The contents of the indicium are then hashed (MD5) into a message format and the resulting message is digitally signed by transaction server 180 using the well-known DSA. The indicium is then encrypted for the client to decrypt. The indicium is encrypted to prevent unauthorized capture of the indicium. An unencrypted indicium could be captured, printed, and entered into the mail stream prior to it being obtained by the authorized customer. The results of this process are sent back to the Host 10n for formatting and printing. As each indicium 74 is hashed, the appropriate postage amount is deducted from the customer's descending register 21n on PSD 20n located on the master server 300. A copy of the updated PSD register 21n is then downloaded to the Host 10n for display to the customer 2n. Once the Host 10n has successfully received the indicia, the connection to the web server 150 can be terminated. A server connection is not required during the physical printing process. The number of indicia that can be downloaded and printed at one time is limited only by the amount of disk space available on Host 10n. Each indicium will typically consume 2K of disk space for the aforementioned two dimensional matrix codes and data. The following information is then printed on the envelope or labels: Return Address (optional) 71 (previously entered during registration or changed via Configure), mailing address 72 (obtained from list), graphic image 73 (if selected via page setup screen), and indicium 74 (constructed when "print all" is pressed). See open system pc-based indicium printing 23 on FIG. 1A and FIGS. 4A and B. For example, one proposed indicium 74 is illustrated in FIG. 4A, which, among other things, conforms to the specifications in the Domestic Mail Manual--P050, dated Sep. 19, 1996. A Test Print Quality button also may be provided. Pressing this button causes a sample envelope to be printed. This envelope can then be mailed to the PSP 4 as a quality assurance test of the user's Host 10n system and printer 70n. See FIG. 1A mail plan audit 41 This button is preferably rendered inactive, except when the Quality Assurance (QA) Date stored is more than three (3) months prior to the current date. In that case when the Test Print Quality button is pressed an envelope is produced and the QA Date is set to the current date. l. List Management A List Management feature is preferably provided which allows users 2n to create and manage mailing lists within the Host 10n and is initiated by selecting a Manage Mailing Lists screen. Optionally, the user 2n can choose to import a mailing list from a non-Host system file, and the system will preferably will support a number of mailing list formats. Once the file is created via an import it can be automatically sent to the cleansing function, either CD-Rom or on-line, edited, cleansed again if appropriate, saved if desired, and set up for postage purchase. m. Postage Correction A postage correction feature allows the user to print a correction indicium in the event that the postage amount or the postage date is incorrect. It is initiated by selecting a Correct Postage screen and choosing the appropriate correction for a postage amount or a postage date. Invalid information will be identified once valid information is provided. A connection is made to the PSP 4 server 150 and the correction transaction is validated. Notification is sent to the Host system 10n and the user is informed whether to place the envelope back in the printer 70 in the same direction as the first printing or to reverse it before printing. Security The present invention advantageously uses the internet 30 connection for registration, client/server authentication, transmission of credit card information, transport of indicia, requests for refunds, change of personal/address information, and the exchange of addresses for cleansing. Each of these transactions will require different types of security to ensure the safe exchange of information between the Host 10n, PSD 20n, and printer 70n. Conducting financial transactions over an unsecured channel such as the internet 30 requires the use of cryptographic modules. In the present invention, each client 2n has a cryptographic module 12n and the RSP server 4 has a cryptographic module 14. The server cryptographic module 14 serves three functions: (1) authentication, (2) encryption, and (3) authorization. Authentication is the only function that requires interaction with a client cryptographic module 12. This is discussed below. The physical architecture of the system of the present invention was designed to ensure that all access to the system is through secured and monitored points. The entire system that is at PSP 4 will reside on a private network and the transactional portions will be connected through a firewall 160 to the internet 30. Firewall 160 will be configured to restrict all network traffic to a single TCP/IP port 140. All packets received by the firewall 160 on the specified port will be routed to a Transaction Manager (i.e., transaction server 180. It is noted that the actual implementation may have a plurality of transaction servers 180n, and routing a given packet to a transaction server 180 may be based on an address field in the packet or on a first available server, as the case may be. Once a transaction server 180n receives the packets that request a socket connection, a socket connection will be established. The transaction server 180 will immediately require that each particular connection authenticates a client 2n, or the connection will be dropped. To ensure this safe exchange, the implementation of security uses the following assumptions: The host 10n and PSD 20n functions will not reside on the same machine. The PSD 20n functions will not be stored in a separate hardware device connected to the customer's PC. The Host 10n will exist on the customer's PC and the PSD 20n will exist on the PSP 4 network infrastructure. The Internet 30 will be used to interconnect a customer's host 10n and printer 70n with the PSD 20n. All transactions between the Host 10n and the PSD 20n will be encrypted. All transactions between the host 10n and the PSD 20n will be digitally signed. All indicia 74 will be digitally signed. All indicia 74 will be encrypted for client 10n to decrypt prior to printing. Prior to initiating a transaction, both the client 10n and the provider transaction server 180 will authenticate each other. A customer's actual existence and proof of valid physical address will be initially established by sending the system license and registration information to the customer by mail. All cash management functions will be performed within the treasury component of the RSP 4, namely, payment server 190, separate from the PSD 20n functionality. The following discussion describes a preferred security model to be implemented. The downloaded client software performs all Host 10n and printer 70n functions, as defined by the appropriate IBIP specifications. The transaction server 180 performs all of the PSD 20n and TPS 6 infrastructure and support functions, as outlined by the IBIP specifications. Each client 2 and server 4 is comprised of its own cryptographic module 12 and 14, respectively. For authentication and key expiration/regeneration the two modules 12 and 14interact. a. Client Cryptographic Module Security The cryptographic module 12 is used to authenticate the customer 2n to the TPS 4 (hereinafter also referred to as "server 4"), the server 4 to the client 2n, and to manage the authentication key pair (public key/private key) that exists on the client 2. The main function of the client cryptographic module 12 is to protect the customer's private key from both intrusion and corruption. The customer's private key is used to authenticate the client 2 to the server 4. To protect from intrusion, the private key is preferably stored on a diskette (designated A: or B:) in a ciphertext key form. The ciphertext key is decoded when the customer enters their password. Thus, the plaintext form of the private key exists only in RAM. When cryptographic operation is completed, the plaintext key is zeroized. To ensure the integrity of the private key, a hash of the key is concatenated to the key prior to creation of the ciphertext key. When the ciphertext key is decoded, the key is hashed and compared to the stored hash to determine the key's integrity. The components of the client cryptographic module 12 are: Client Private Key, Client Public Key, Server Public Key and Customer Identification Number. The algorithms used by the cryptographic module, each themselves well known, are: (1) RSA, (2) MD5 and (3) RC2. The system is designed so that client 2 needs to provide no physical security to protect the cryptographic module 12. This is because no key is stored in plaintext form and the decryption process is performed only when needed. After a key has been used it is zeroized in memory. At no point are the keys and/or password accessible on the hard disk in a plaintext form. i. Description of the Client Cryptographic Module The cryptographic module 12 preferably exists within the context of what is called a CryptoManager. The CryptoManager is preferably a C++ object stored as a statically linked DLL. When the client software is loaded into memory, it will create an instance of the CryptoManager object. By statically linking the CryptoManager Object to the Client, it can be assured that no other program has access to the DLL, hence protecting the CryptoManager's services. The most important responsibility that the CryptoManager assumes revolves around protecting a file known as the Key File. The Key File will contain the necessary information to uniquely identify and authenticate a client 2n to the server 4. It is composed of four items. 1) The Client's Public RSA Key; 2) the Client's Private RSA Key; 3).the Customer Identification Number; and 4) A Digital Hash of 1, 2, and 3. ii. Key File Download Referring to FIGS. 5 A-C and 6A & B, the server 4 generated key file is made available to the customer after a successful registration. The customer 2n is mailed a letter containing instructions on how to download the key file, a user name, and two passwords. One password is used to logon to the web server 150, establish an SSL 3.0 session, and acquire the user's unique key file. The second password will be used to decrypt the contents of the key file. iii. Key Integrity/Protection In order to ensure integrity of the plaintext key, a hash is embedded inside the key file. The whole file is then encrypted with RC2 using a key derived from an MD5 hash of the user's password. Referring to FIGS. 5 A-C, when attempting to open the key file, the user's password 501 in ciphertext is converted into a 160-bit MD5 hash 503. The first 64-bits of the hash is used to both encrypt and decrypt 504 the key file. After the key file has been successfully decrypted, the integrity of the contents must be ensured and another hash of the key file is calculated 507. This hash 507 of everything contained in the key file (public key, private key and user identification number) with the exception of the hash value stored at the end of the file. The resulting hash is then compared at 509 with the hash at the end of the file 501. If the values match, the plaintext key from decrypted 504 is loaded into RAM memory. The user's password (503) is not stored. iv. Key Renewal The key file is preferably provided a mandatory life span that will be enforced by the Host 10n's cryptographic module 12. After a designated period of time, the Host 10n will open an interface 530 that will require the client to re-generate a new pair of public and private keys 532. The client will generate a new key, using a standard Microsoft CryptoAPI.TM. function, calculate a hash of the key file, encrypt the key file using the first 64 bits and store the generated key pair as ciphertext keys 535. The client 2 will then send the new public key to the web server 150. The client cryptographic module 2 will authenticate with the cryptographic module 14 of server 4 to verify that the key-renewal process was successful. v. Password Change Typically, the user will be required to change the password the first time it runs the downloaded client software. The user can also change the password at any time after the initial requirement. The crypto-manager will expose an interface 520 that allows the client to perform this task. The interface will require that the user provide both the old and the new password 521. Once the password has changed, the key file will be decrypted using the old password and then encrypted with the new password 522. The key is stored as ciphertext 523 and will not be in plaintext form. vi. Authentication The authentication service is responsible for authenticating each client 2n with the server 4. As illustrated in FIG. 7, a sequence of three messages is transmitted between the client 2n and the server 4. E.sub.spu refers to RSA encryption using the server's public key. E.sub.cpu refers to RSA encryption using the client's public key. In the case where the client 2n fails to authenticate with the server 4, the authentication protocol is terminated and the communication link between the client 2n and server 4 is severed. If the client 2n is able to successfully authenticate with the server 4, then the session keys exchanged and established during authentication can then be used to encrypt communications between the client 2n and server 4. Authentication is discussed more fully below in connection with server 4. vii. House Keeping After authentication, the client 2n executes a HouseKeeping Service. This Housekeeping service is responsible for notifying the client software of any new postal table information or changes and of key expiration events. The HouseKeeping Service queries the server 4 to ensure that current keys have not expired. If the keys are about to expire the client 2n will issue a command to renew the keys and a new public key will be sent back to the server 4. The client 2 must then re-authenticate with server using the new keys. If the keys have not expired, then the HouseKeeping Service will check the postage rate tables. If the postage tables need to be updated, the client 2 will submit a request to server 4 for new postage tables. If the keys have not expired and postage tables do not need to be updated the HouseKeeping service exits. viii. Finite State Machine With reference to FIG. 8, the finite state model defines a preferred set of system access rules. The model defines secured and unsecured states and all state transitions. When the client software is executed, the client cryptographic module 12 initially enters a Self-Test State 910. The Self-Test State 910 is when all self-tests are performed. If all self-tests pass successfully the module proceeds to enter the Un-Initialized State 920, otherwise the module will enter into the Error State 950. When a client 2 to server 4 transaction is initiated, the cryptographic module 12 enters the User State 930 and/or the Crypto-Officer State 940 as described below. The Error State 950 indicates that an unrecoverable error has occurred. If the module 12 enters the Error State, the module will no longer perform cryptographic functions. If keys are loaded into the module 12 when the cryptographic module enters the Error State, all keys will be cleared from the module. The Cryptographic module 12 enters the Un-Initialized State 920 after the Self-Test State 910 has completed and no errors have been reported. No keys are loaded into the module during the Un-Initialized State and therefore no cryptographic functions can be performed. If the cryptographic module attempts to perform cryptographic functions while the module is in the Un-Initialized State 920, the client software will first check to make sure that a key file is present. If no key file is found, the module will prompt the user to register the software and download a key file. If a valid key file exists, the user is challenged with a password. The password is used to attempt to open the file. If the password successfully decrypts the key file, the cryptographic module enters into the Key Entry State 960. If the password is not able to successfully decrypt the key file then the module remains in the Un-Initialized State 920. If the key file has been corrupted or compromised then the module enters the Error State 950. In the Key Entry State 960 the cryptographic module 12 loads the keys obtained from key file. The Initialize function of the Crypto-API library is used by the cryptographic module as a means of initializing the crypto-context with the keys. The User Services State 930 is used to perform all cryptographic functions, not related to key management, which are performed by the cryptographic module 12. As soon as a key-related function is complete, the plaintext keys in memory are zeroized and the module enters the Un-Initialized State 920. The Crypto Officer State 940 is entered only when the key file needs to be updated. This will happen either when the user changes the password or when the current RSA keys expire and need to be changed. The server 4 during authentication will trigger replacement of expired keys. The Idle State 970 illustrated in FIG. 8 is used in the server cryptographic module 14discussed below, but not in the client cryptographic module 12, which either works or does not work, but does not remain idle. b. Server Cryptographic Module Security The server cryptographic module 14 of server 4 is responsible for protecting two categories of data. These two categories are Cryptographic Keys, and the transactional PSD 20n Registers 21n and 22n. In addition, the server cryptographic module 14 will be responsible for managing all "certificates" that exist on the server 4. All of these data items have been placed within the server cryptographic module 14 and are protected by its security policies. In addition to protecting sensitive data, the server cryptographic module 14 runs many security services. These services include client authentication, key management and PSD management. The security services are governed by policies that dictate who can access them and what data they can control. The client 2 has no direct control over the services performed by the server cryptographic module 14. All services performed by the server cryptographic module 14 are under the direct control of a Transaction "Manager" server 180. Once the client 2 has been authenticated, it submits a transaction request to the transaction server 180 and waits for a response. It now becomes the job of the Transaction Manager to process the transaction and return a "receipt" to the client 2. All transaction "receipts" will contain a date/time stamp, and a sequence number and a digital signature to verify the authenticity of a transaction in relation to other similar transactions. For a given customer 2n, the sequence number will increase by one each time until a threshold is met, e.g., 10,000, at which point the counter will reset to 1. The Transaction Manager embodies the logic required to complete a transaction while enforcing the security and integrity of the server cryptographic module 14. Based on the authenticated user 2n, the transaction requested, the date/time stamp, and the sequence number, the Transaction Manger would determine whether the requested transaction is valid. The Transaction Manager will complete the transaction by sending a receipt, including a digital signature as evidence of payment for the transaction, back to the client 2n. In the case of the postage purchase system, the receipt is the indicium 74, which includes the foregoing and the postage related information (addresse, postage amount, etc.). The Transaction Manager server 180 also is responsible for performing non-cryptographic functions. For example, address cleansing, credit approval and customer profile changes, which are performed by transaction server 180, do not require the use of cryptographic functions, and are therefor considered outside the realm of the server cryptographic module 14. The server cryptographic module 14 serves three essential functions authentication, encryption and authorization. Authentication is the only function that requires interaction with the client cryptographic module 12. This interaction is secured in a manner described elsewhere. i. Physical Security The physical security of the server cryptographic module 14 will be protected by measures taken to securely house the server 4, and its backup, preferably in a locked and guarded site. All servers will be stored in locked cages that will be accessible only to the system's administrator. Access to the building housing the servers will be limited to authorized personnel only. In addition, a TIS firewall 160 will be used to protect the single port 140 that will be available to the Internet 30, and restrict traffic entering the server segment to TCP/IP packets only. ii. Cryptographic Module Data The server cryptographic module 14 manages cryptographic keys, certificates and PSD registers 21, 22. All sensitive data is stored in a Secure SQL Server Database and protected by SQL Integrated NT security. See FIG. 3. The Secure SQL Server database 305 is considered a part of the server cryptographic 14 module and may only be accessed by the cryptographic module. iii. Cryptographic Keys The Cryptographic keys are utilized by the cryptographic module 14 to perform two main functions, authentication and indicium generation. The cryptographic module stores the following keys. Client Public Authentication Keys (RSA) A Client Public Authentication Key exists for every registered user. They are used to prove the client's identity when it attempts to establish a connection with the server 4. This will be typically a 1024 bit key. Server Public/Private Authentication Key Pair (RSA) Only one pair of Server Public/Private Authentication Keys exists on the server 4. These are used to prove the server's identity when the client 2n attempts to establish a connection with the server. This will be preferably a 1024-bit key. Client Private Indicium Keys (DSA) A Client Private Indicium Key exists for every registered user 2n. It is used to generate the digital signature required to produce an indicium 74. This will be a 1024-bit key. Server Internal Private Key (DSA) This key is used to sign data that will be used to communicate with the TPS 6, in this embodiment, the USPS. This will be a 1024-bit key. iv. Certificates Certificates are data structures that bind public key values to subject identities. The binding is achieved by having a trusted Certification Authority (CA) digitally sign each certificate. By verifying the Certification Authority's signature on the certificate, one can be confident that no substitution of the information within the certificate has taken place. There are two classes of certificates used by the cryptographic module 14. The first class is the ITU-T X.509 standard (formerly CCITT X.509 (referred to as the X.509 certificate)). The second is a USPS IBIP deviation that does not use the ASN. I encoding scheme, and has very few fields in order to minimize the required storage space for the certificate. This second certificate is reserved for the PSD 20n. The certificates used by the cryptographic module 14 essentially complement the private keys described in the above section with the exception of the Server Authentication Keys. The Client Indicium Certificate is the data used to generate the digital signature of the indicium. The actual signature is signed with the complementary key of the certificate's public key. This way, based on the contents of the certificate, an exterior entity can verify authenticity of the generated indicium 74. The Server Certificate is used by the USPS to confirm the server's identity. The USPS requires that the server 4 periodically communicate with it to transfer information regarding postage sold. This certificate is used to ensure safe delivery of this information. The Certification Authority Certificate issued by the Certificate Authority allows the server 4 to verify messages sent by various other parties that have been certified by the same Certification Authority. The X.509 Certificate is the current standard for digital certificates, and it defines the following fields: 1. Version: For forward and backward compatibility. 2. Serial Number: An integer that, together with the CA's name uniquely identifies this certificate. 3. Signature: Specifies the algorithm used to compute the signature on the certificate. 4. Issuer: Name of issuer of the digital certificate. 5. Validity: The time duration and period for which the certificate is valid. 6. Subject: Name of entity whose key is being certified. 7. Subject Public Key Information: Entity's public key. 8. Issuer's Unique Identifier: Optional, uniquely identifies the issuer of this certificate. 9. Subject Unique identifier: Optional; uniquely identifies the subject of this certificate. 10. Algorithm Identifier: Same as Signature. 11. Encrypted: The actual digital signature generated by the algorithm specified in field 3. Field 3 is typically used for encryption algorithms, such as DSA or RSA. They operate on the basis of having two unique keys: a public and a private key. Signing an item with a private key means having the ability to verify it only by using the corresponding public key. The private key is securely kept in a location that is only accessible to its intended users; knowledge of someone's private key means having the ability to impersonate them. The public key is made publicly available to all individuals wanting to verify an item that is digitally signed by the user. The public key is made available in the X.509 certificate (field 7). For example, if user A wanted to verify the digital signature of an item issued by B, user A would request that B send an X.509 certificate. User A can then verify the authenticity of the X.509 certificate by looking at the digital signature contained as part of the certificate (field 11). If the certificate were issued by a trusted third party (Certificate Authority) such as the USPS then user A would already have the USPS X.509 certificate. User A would first extract the USPS public key from the X.509 and use that to verify the signature in B's X.509 certificate. If the signature verifies then the X.509 certificate is authentic (or at least according to the USPS), user A can then extract B's public key from the X.509 certificate and similarly verify the digital signature of the item issued by B. User A can then optionally store B's digital certificate. The implementation of the software is in accordance with the IBIP specification document. In the registration process, a new user 2n would contact the server 4 with information that uniquely identifies him/herself The client's host 10 would generate a pair of public/private key pairs and would send securely the public key up to the server 4. The server 4 would then take the public key information and send that along with any other necessary information to the USPS in order for the TPS 6 USPS to generate the user's X.509 certificate. The host 10 would print out a written agreement that will be hand signed by the user 2n of the system and mailed to the TPS 6 USPS . When the USPS receives the signed agreement it will then generate the X.509 and send it to the server 4. The server 4 will in turn forward the certificate to the host machine 10. An alternate system would provide the server 4 as a trusted third party (Certification Authority). The USPS can then utilize the server 4 public key to verify authenticity of printed indicia. A printed indicium can be associated with the third party provider 4 who issued the certificate by checking the issuer's name field. v. PSD Registers The PSDs 20n are the devices used to track how much postage both individual clients 2n and the server 4 own. The PSD 20n contains ascending and descending registers 21n and 22n that keep track of the total amount of postage a user 2n has spent and owns. The server 4 maintains a separate PSD 20n (indicated by a letter subscript "n") for each registered customer. This keeps track of the total amount of postage each customer owns and has spent. The server 4 also maintains a master PSD 40 with ascending and descending registers that keep track of the total postage it owns and has sold. The following Table III is a summary of the data typically maintained within the cryptographic module 14.
TABLE III
Cryptographic Keys Certificates PSD Registers
Client Public Client.sub.n Indicium Client PSD 20
Authentication Key Certificate
(RSA)
Client Private Indicium Server Certificate Master PSD 40
Key (DSA)
Server Public/Private Certification
Authentication Keys Authority Certificate
(RSA)
Server Internal Private TPS 6 Certificates
Key (DSA)
vi. Server Cryptographic Module 14 Services Authentication Service The authentication service is responsible for ensuring that only authorized users 2n have the ability to submit transaction requests. It will utilize the client's public authentication keys to perform the user validation. Upon successful authentication the transaction manager (server 180) will handle the user's transaction request. Key Management Services The Key Management service will be responsible for key generation, expiration, archiving and distribution. These operations are performed on cryptographic keys and certificates. There are three levels of authority involved in key management. They are the server, client and the Certification Authority (CA). The details of how/why these keys are generated can be found under the Key Management section in the description of the cryptographic module 14 . Indicium Generating Service This service is used for the generation of indicium 74. It requires access to the PSDs 20n, the client's private indicium key, and the certificate. Registration Service The Registration Service is outside of the cryptographic module 14. It is essentially responsible for adding new users to the PSP 4 system. It communicates with the Transaction Manager server 180 to generate a new encrypted user key file, which is later downloaded by the client 2. Cryptographic Module Roles The cryptographic module 14 supports the use of two roles to perform different cryptographic functions. The first role is the Crypto-Officer that is responsible for performing all the key management functions. The other role is the Crypto-User, which has access to use cryptographic functions and keys for the purposes of authentication and indicium generation. The roles provide a logical separation between operators and the services they are allowed to perform. vii. Description of the Cryptographic Module Authentication and Encryption When a client 2n establishes a connection with the server 4, the server 4 immediately enters an authentication protocol as illustrated in FIG. 7. The first step of the routine is to authenticate the client 2n. The client 2n sends its customer ID in plaintext form. This information is used to verify that this is a valid customer and retrieve that customer's public key. The client 2n creates a random session key, identified in FIG. 7 as Session Key A. The client 2n then uses the server's authentication RSA public key to encrypt Session Key A, and transmits the encryption to the server 4. The server 4 receives and decrypts the key using its private authentication key. The server 4 then creates a random session key of its own, identified in FIG. 7 as Session Key B. The server 4 uses the client's public authentication key to encrypt Session Key B, and transmits the encryption to the client 2n. The client 2n receives and decrypts the key using its private authentication key. The server 4 also builds up a hash value of Session Key A, the client ID, Session Key B, the server ID and the text "phase 2". This hash value is sent to the client 2n concurrently with the encrypted Session Key B. The data is hashed in a standard sequence, so that the client 2n will be able to properly validate it. The client 2n receives the server's hash value and then validates it by creating a hash value of its own containing the same data, and by comparing the two hash values. At this point, if the two hash values do not match, the protocol is terminated and the communication link between the client 2n and server 4 is severed. If the hash values do match, the client 2n then builds up another hash value, containing Session Key B, the client ID, the server ID and the text "phase 3". This hash value is sent to the server 4, which validates it by creating a hash value of its own containing the same data and comparing the two hash values. If the two hash values do not match, the protocol is terminated and the communication link between the client 2n and server 4 is severed. Once the client 2n and server 4 have exchanged session keys and hash values and the hash values have been properly validated, the protocol is complete and the client 2n and server 4 have been authenticated to each other. Session Key A and Session Key B can then be used by the client 2n and server 4, respectively, to encrypt and secure communications to each other. The session keys generated during the authentication process are preferably 64-bit RC2 symmetric keys, which are used to encrypt and decrypt all data sent between the client and the server. A hash of the data value is appended to all transaction request data or a transaction receipt before it is encrypted and sent to the other party. The recipient uses the hash to ensure message integrity. If the message is found to be corrupt or altered in some way, the transaction will be aborted. At the end of the Authentication protocol, the client cryptographic module 12 will store the Customer ID and the session keys as part of the initialization routine. This information will then be available to all services running under Crypto-User role for a particular user. Key Management The transaction server 180 is concerned with two types of public/private key pairs, authentication and indicium generation. Authentication keys are 512-bit RSA keys and the indium generating keys will 1024-bit DSA keys. Both the client 2 and the server 4 each have a pair of authentication and indicium generating keys. Client Authentication Keys The server 4 initially produces the client authentication keys. The server first generates the client's public/private RSA 1024-bit keys. It then bundles the client keys, the server's public key and the client's identification number into a single file. A MD5 hash of the file is produced and appended to the end of the file. Finally, the server 4 takes the content of this file and encrypts it with a random number that it generates. The produced ciphertext is referred to as the key file. The server generated password initially used to encrypt the key file is mailed to the client, as explained in the registration procedure described above. The key file is then exported from the server's cryptographic module to a SSL 3.0 password secured web site 150. The customer can then change this password in a subsequent session. The client authentication keys will have an expiration period. The duration of this period will be, for example three (3) years, as determined by the USPS Key Management Specification. To prevent checking for key renewal every time a client 2n connects to the server 4, all client keys may be set to expire at the same time. After a client 2n authenticates with the server 4, the server 4 will notify the client if its keys have expired. At that time, the client will generate a new set of keys and send the public key to the server. The server only stores the client's previous public authentication key. The private key is kept private with only the client. The public key is kept inside a password protected SQL master database 305 (FIGS. 4, 7) that is accessible only by the server cryptographic module 14. In the scenario when a user 2n requests a full refund, that user's keys are destroyed and their record removed from the SQL database 305. Server Authentication Keys The software product will execute a key generation routine. This routine will produce the server's public/private RSA 1024-bit authentication keys. The key will be stored on a secured SQL master database 305. The public/private keys will have an expiration period defined by the USPS. When the server's keys expire, it will regenerate a new pair of authentication keys. With every client record, a field will be used to indicate which version of the server public key its using. During authentication, the server 4 will retrieve the appropriate version of its authentication public key. If the client 2n is using an expired key, the server 4 will download the new key to the client 2n. The client's record will be modified to reflect the new key version. The server 4 will keep its old authentication keys archived for a specified period of time. This allows a client 2n who has not connected since the server's public key expired the ability to authenticate and download the server's current public key. Certification Authority Certificate The Certification Authority (CA)'s certificate is the only self-signed certificate on the system. The public key in the certificate corresponds to the private key used to sign the certificate. This makes the Certification Authority certificate easily susceptible to fraud if proper distribution mechanisms are not employed. The initial CA's certificate will be distributed by means of regular US certified mail. Included with the CA's certificate will be a hash of the next certificate key values. When a certificate expires, the USPS certification authority will issue a new certificate and sign it with the old certificates matching private key. The USPS CA will send a new certificate signed with the CA's new private key to the server 4. The server 4 will validate the certificate for authenticity by first checking to ensure that the new CA certificates public key authenticates the included signature. It will then hash the keys included with the new certificate to verify that the hash value match with the old hash included with the old CA's certificate. If both conditions validate, the old CA's certificate is deleted and replaced with a new CA certificate. Client and Server Indicium Keys and Certificates The client 2 and server 4 indicium keys are used to generate indicium 74 and all reside on the server 4. A client indicium key pair exists for every registered customer 2n while there is only one pair which exists for the server 4. All indicium key pairs are generated on the server 4. The private keys are immediately stored in the SQL master database 305, while the public keys are sent in a request to the Certification Authority of the USPS for certificate generation. The USPS will generate the certificates and send them to the server 4, which will verify the certificate's source and store it in a SQL master database 305. The first step to indicium generation is generating a public/private key pair for the server 4. The public key is sent to the Certification Authority and a certificate for that server 4 is generated and returned to the Server. The Certification Authority also retains this certificate so that the Certification Authority can verify the authenticity of future server requests. Similarly, the server 4 will have copy of the CA's certificate to verify the authenticity of data being sent back from the CA. The server 4 needs a public/private key pair for each client 2n in order to produce indicia. The server 4 will generate a key pair for the client 2n, store the private key in the secured SQL master database 305 and send the public key to the CA as a request. The request is signed with the server's private indicium key and sent to the CA, where the request will be authenticated using the server's certificate. The CA will send the certificate back to the server. The returned certificate will be packaged with some other information and digitally signed by the CA. Using the CA certificate the server 4 will verify the authenticity of this returned package. Both the client 2n and the server 4 indicium keys will expire after specified period of time. Once it has been determined that indicium keys have expired, a new set of public/private keys will be generated and a new set of certificates will be requested. Because all indicium keys are located and managed by the server 4, the client 2 is not aware that its indicium keys have expired or been replaced. All old keys are permanently removed from the server. Indicium Generation The server cryptographic module 14 is responsible for completing the task of indicium generation. When an indicium generation request is passed to the cryptographic module 14 through one of its interfaces, the data included will be missing the client's indicium certificate and the PSD 20n register values. The cryptographic module 14 will retrieve the appropriate values from the SQL master database 305 and fill in the remaining values. The result is then signed with the client's private indicium key. The actual indicium 74 is the concatenation of data and the digital signature. Because of the presence of the client's certificate (which was signed by the USPS CA) the indicium 74 can be easily verified for authenticity by using the public key embedded in the client's 2 indicium certificate. The completed indicium 74 is returned back through the cryptographic module interface and ready to be sent to the client 2n. The data included in the indicium 74 can include, for example, the user 2n, the addressee of the recipient, the postage, the rate table used to calculate the postage, the date, time and preferred postal office/box/pickup location, etc. Postal Security Devices (PSDs) The PSDs 20n will actually reside on the secured SQL master database 305, although illustrated separately on FIG. 3. Each client 2n will have its own record representing its PSD 20n, while the server will have one master PSD 40. A client PSD 20 record will contain four fields: Ascending Register 21, Descending Register 22, Maximum Descending Register 25 and Refund Register 24. The Ascending Register 21 measures a count of the total dollar value of postage a client 2n has ever spent. The Descending Register 22 measures a count of the current dollar value of postage that a client 2n has bought, but not used. The Maximum Descending Register 25 is a total dollar value that a client 2n is allowed to own at a particular time. The value of the Descending Register 22 can never be more than the Maximum Descending Register 25. The last field in the client PSD 20n is the Refind Register 24 which tracks the total dollar amount of postage that a client has had refunded. The Master PSD 40, also resident on master database 315, contains three fields: Ascending Register 44, Descending Register 45, and Refund Register 46. The Ascending Register 44 measures the total dollar amount of postage that the server has sold to clients. The Descending Register 45 measures the total dollar amount of postage that the Server has to sell to clients. The Refund Register 46 measures the total dollar amounts of postage that server have refunded to clients. The following graphical user interfaces are used in the server cryptographic module 14 for security. PutNewCAX509 (Certificate [in], status [out]) This interface is used to replace the CA's X.509 certificate in the cryptographic module 14. A new certificate is passed into this interface and a status report is returned. The status will indicate if the certificate has been successfully changed. As part of this procedure, the cryptographic module will verify the authenticity of this new certificate. CreateKeyFile (CutsomerID [in], KeyFile [out]) This interface is used to create the keyfile that the client 2n downloads from the registration web server 150. Encrypt (PlainText [in], CipherText [out]) This interface will encrypt all the plaintext that it receives as an argument and outputs it in ciphertext. The cryptographic algorithm will be 64-bit RC2. The key used in this function remains inside of the cryptographic module, it is generated by the authentication routine. Decrypt (SessionKey [in], CipherText [in], PlainText [out]) This interface will decrypt all the ciphertext that it receives as an argument and outputs it in plaintext. The cryptographic algorithm will be 64-bit RC2. The key used in this function remains inside of the cryptographic module, it is generated by the authentication routine. CreateIndicium (IndiciumData [in], Indicium [out], status [out]) This interface allows for the creation of indicium 74. An incomplete indicium is sent into the cryptographic module 14, the module then performs cryptographic functions on the indicium 74 and returns it to the calling procedure. Authenticate (OpenSocket [in], status [out]) The authentication interface will be called to verify and authenticate the identity of the client 2n. It is passed a handle to the current open socket of the client requesting a connection to the server. The status will indicate whether the client has successfully authenticated. CreatelndiciumKeys (status [out]) This interface will be used to create new client key pairs used for indicium generation. Add postage to Master PSD (Amount [in], status[out]) This interface will be used to add more postage to the Master PSD 40. The function will modify the appropriate registers to reflect any changes in how much postage the server 4 owns. The status will be used to indicate if the call was successful. Add postage to Client PSD ( status [out]) This interface will be used to add more postage to the client PSD 20n. The function will modify the appropriate registers to reflect any changes in how much postage the client 2n owns. The status will be used to indicate if the call was successful. GenerateServerAuthenticationKevs (status [out]) This will be an administrative function that will generate a new authentication key pair for the server 4. The status will indicate whether the function completed successfully. StoreClientPublicKey (PublicKey [in], status [in]) This interface will allow the client's public authentication key to be updated in the cryptographic module's database. The status will indicate whether the function completed successfully. RefundClientPSD (RefundAmount [in], status [out]) This interface will be used to reimburse postage to the client PSD 20n. The function will modify the appropriate registers to reflect any changes in how much postage the client owns. The status will be used to indicate if the call was successful. Finite State Machine Referring to FIG. 8 again, the finite state model defines the set of system access rules for the server cryptographic module 14. The model defines secured and unsecured states and all state transitions. When the software is executed, the cryptographic module 14 enters the Self-Test State 910. For example, the first test will verify that the executable module check-sums are correct. This will ensure that none of the code has been corrupted or modified. Next, the cryptographic algorithms will be tested. The RSA, RC2 and MD5 cryptographic algorithms will be tested using the "known-answer" test. A known value will be applied to the algorithm to determine if it will reproduce a known result. If the resulting value matches the expected result, the algorithm is assumed to be functioning properly. Since the DSA algorithm does not reproduce the same value twice, it will use pair-wise consistency test. This test will first sign a quantity with a private key and then verify the signature of this quantity using the public key. If the result of the verification is successful, the test succeeds. If any of cryptographic modules tests fail, it is assumed to be malfunctioning. If all self-tests pass successfully, the module proceeds to enter the Un-Initialized State 920, otherwise the module will enter into the Error State 950. No keys are loaded into the module during the Un-Initialized State and therefore no cryptographic functions can be performed. It is in this state that authentication service starts. Based on the authenticated user and the requested transaction, the cryptographic module will determine whether the next state should be the Key Entry State 960 or the Crypto-officer State 940. This decision will depend on whether the transaction will use the cryptographic module to perform key management or other cryptographic functions. Because the transactions of multiple clients 2n will be handled simultaneously, the cryptographic module 14 will support a finite state machine that can be in the Idle State 970, Key Entry State 960, and Crypto-Officer State 940 at the same time. If key management functions are called, the module 14 enters the Crypto-officer State 940. In the Idle State 970, all cryptographic keys have been loaded into the module. The module is now initialized and remains idle until cryptographic functions are called. Once cryptographic functions are called the module moves into the User State 930. If a request is made to terminate the process, the module will clear all loaded keys from memory before transition to the Un-Initialized State 920. The User State 930 is used to perform all cryptographic functions, not related to key management, that are performed by the cryptographic module 14. As soon as a key-related function is complete, the module transitions back to the Idle State 970. If the cryptographic module 14 is not going to perform key management features it will be loaded with the keys of the current user. At that point, the module enters the Idle State 970 and remains there until either a cryptographic function is called or the process is ready to end. Keys will be created or modified and stored in the secured SQL database 305. The cryptographic module 14 will clear all key information from memory and transition back to Un-Initialized State 920. If cryptographic functions are requested from the Idle State 970, the module 14 enters the User State 930 to execute the requested cryptographic function. After the requested function is performed, the module re-enters the Idle State 970. In the Idle-State 970 or the Crypto-officer State 940, if the process is ready to end the module clears the keys and returns to the Un-Initialized State 920. Each PSD 20n will have its own finite state machine as described above. Only during server 4 initialization and self-test will a single finite state machine be employed. The Error State 950 | ||||||