Fig 1: Example of software distribution system utilizing the superdistribution architecture
The technical innovations that we describe here are best understood in the context of a network that provides superdistribution of S-programs and the files needed in a user's computer in order to support the use of the superdistribution services. We emphasize, however, that distributing the S-software itself is not a function of the network since a user can obtain that software by any convenient means--from a bulletin board, making a copy of a friend's program. or perhaps purchasing a collection of S-programs at a nominal price. S-programs are stored and transmitted in encrypted form. so the transmission paths need not be protected in any way.
Figure 1 illustrates a typical software distribution system that utilizes the superdistribution architecture. Each S-computer that is, an end-user computer supporting superdistribution, is equipped with an S-box. The S-box contains a metering program. the Software Usage Monitor (SUM), that enforces the terms set by each software vendor for executing that vendor's products and keeps track of how much the user owes to each vendor. The S-box generates a payment file that contains this information. The fees charged for software usage are measured in units that we call S-credits. Payment files are encrypted and transmitted to the collection agency through the network as shown in the figure.
The collection agencies receive the payment files from users, process those files, and transmit payments to vendors - both the authors of the S-programs and the manufacturers of the S-boxes. Each collection agency has an S-box in its computer. The payment files are decrypted and processed under control of this S-box so as to ensure the integrity of payments to the vendors of S-programs and of the supporting hardware as well.
The clearinghouse keeps track of funds transfers engendered by superdistribution. The clearinghouse can be either a new organization or an existing one. e. g. a credit card company. that is prepared to provide the necessary services. The advantage of creating a new organization is that it provides additional degrees of freedom in the systems design. The disadvantage is that it requires a large initial investment. Using an existing organization as the clearinghouse not only saves that investment but also gives that organization the opportunity to enlarge its market.
Identification numbers (ID's) are essential to this arrangement. Each user. each software vendor, each S-box manufacturer, and each collection agency has a unique ID. In addition. users can also have ID's. either as individuals or as organizations. The ID of a user is usually in a different name space than the ID of that user's machine. User ID's provide a convenient mechanism for establishing credit. since they are associated with the individual or organization who is actually paying for the software. (An organization or even an individual may have more than one machine.) On the other hand, a software distribution system based purely on S-box ID's can provide a high degree of privacy for users.
Requiring prepayment for software usage avoids any risk of default, but such a requirement is unattractive to users and negates the social benefits that we hope to see provided through superdistribution. It is easy to understand why this should be so if we consider how people would react to being required to pay for all their water and electricity in advance.
Fig 1: Example of software distribution system utilizing the superdistribution
architecture
The superdistribution scheme does not provide any absolute guarantee that users will pay what they owe, or even that they will return the necessary payment files to the collection agents. However, the S-box, which contains a real-time clock, will suspend its services (other than transmitting payment files) if the conditions, which are specified by the vendor or the system, are not met. Transmission can be either over a telecommunication link or with a memory card. In the event that a user transmits the payment files but does not remit the corresponding payment, a collection agent can apply appropriate sanctions.
Superdistribution does not rely on the honesty or goodwill of the manufacturer of the S-box. It is even possible to protect software designed for the S-box against attacks perpetrated by the manufacturer of the S-box. However, the methods of providing such protection are beyond the scope of this paper.
To join the system, a user need only insert an S-box, most likely in the form of a coprocessor chip, into his or her own personal computer. A collection agency can join the system in the same way. The collection agency needs a slightly different form of S-box, one that contains the software for decoding and processing the payment files. Processing at and between the collection agencies and the clearinghouse can be conveniently handled by a Credit Authorization Terminal (CAT) very similar to the ones now in use in many retail establishments.
Suppose that I am interested in using some S-programs. I obtain an S-box from an agent either in person or by mail. My agreement with the agent includes a credit authorization or a prepayment of, say, $100. I can now use up to $100 worth of S-programs. When I obtain the S-box, I can also obtain a memory card for it. The memory card is used to record accounting information that describes my usage of S-programs as well as the balance in my account.
To renew my usage, I must communicate the accounting information to the agent. I can do this either by establishing modem communication with the agent or by physically presenting the memory card (if I have one) to the agent. Suppose I use a modem. Then I transmit a message specifying my usage to date of each S-program that I have run. This message is generated by the S-box and enciphered so that it cannot be tampered with by anyone. The agent charges my credit card account for that usage and credits the vendors of the software that I have used. He then transmits back to me an enciphered message that resets my authorization to $100.
On the other hand, suppose that I physically present the memory card either in person or by mail. I can either have it renewed on the spot or (if I choose to mail it in) can have a second card sent to me in advance so that I am never without a card.
Superdistribution can also be helpful in conjunction with forms of support for users of S-programs that are not yet provided electronically.
Superdistribution changes the environment for telephone support. First, superdistribution eliminates the need to discriminate illicit and authorized users, because the incidence of illicit usage can be kept reasonably low. Second, superdistribution provides a way of charging for telephone support fairly. An S-program can generate a code number, with internal checking, and charge the user for that code number. The user then calls the vendor, asks his questions, and provides the code number. The vendor validates the code number.
Superdistributed software can be supported by hypertext and other forms of electronic documentation, but such documentation is still unlikely to replace printed manuals entirely. Currently, manuals serve both to educate the user and to provide an additional safe guard for the vendor against piracy (since a user can't buy the manuals separately from the software). With superdistribution, the safeguarding function is unnecessary and paper manuals can be sold as freely as books. In particular, a user can obtain several copies of the printed manuals if he wishes, and can even purchase the manuals without purchasing the software at all. Similar remarks apply to manuals distributed on CD-ROMs, which could be used to generate customized versions of the printed manual for particular configurations of the software, the hardware, or other aspects of the working environment.
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