Superdistribution

The Concept and the Architecture

2. The Superdistribution Architecture

The superdistribution architecture we have developed provides three principal functions:

• Administrative arrangements for collecting accounting information on software usage and fees for software usage.
• An accounting process that records and accumulates usage charges, payments, and the allocation of usage charges among different software vendors.
• A defense mechanism, utilizing digitally protected modules, that protects the system against interference with its proper operation.

In order to participate in superdistribution, a computer must be equipped with a device known as an S-box (Superdistribution Box)[1]. An S-box is a protected module containing microprocessors, RAM, ROM, and a real-time clock. It preserves secret information such as a deciphering key and manages the proprietary aspects of a superdistribution system. An S-box can be installed on nearly any computer, although it must be specialized to the computer's CPU type. It is also possible to integrate the S-box directly into the design of a computer. We call a computer equipped with an S-box an S-computer.

Programs designed for use with superdistribution are known as S-programs. They can be distributed freely since they are maintained in an encrypted form.

In order to make it acceptable to users. software vendors, and hardware manufacturers, the superdistribution architecture has been designed to satisfy the following requirements:

• The presence of the S-box must not prevent the host computer from executing software not designed for the S-box. The presence of the S-box must be invisible while such software is active.
• The modifications needed to install an S-box in an existing computer must be simple and inexpensive.
• The initial investment required to make S-programs generally available must be small.
• The execution speed of an S-program must not suffer a noticeable performance penalty in comparison with an ordinary program.
• The S-box and its supporting protocols must be unobtrusive both to users and to programmers.
• The S-box must be compatible with multi-programming environments, since we anticipate that such environments will become very common in personal computers.

In our current design a program can be written without considering the S-box, but the program must be explicitly encrypted before it is distributed if it is to gain protections of superdistribution. This encryption can be done by a programmer, using the S-box itself.

The design of a superdistribution architecture can be decomposed into four tasks:

• Design of the superdistribution network.
• Logical design of the S-box and its interfaces.
• Design of the supporting software and file structures, including appropriate cryptographic protocols and techniques.
• Design of the protection for the S-box.

Technology for accomplishing each of these tasks is now nearly within to the state of the art. In the rest of this paper we describe our approach to these tasks. We have already designed and constructed two prototype S-computers with their supporting software. Prototype II, the version we are now working with satisfies the six requirements stated above.

[ Next | Prev | Top ]

Virtual School	Middle of Nowhere	Brad Cox