Cryptographic decoder for computer programs

Details Cryptographic decoder for computer programs Cryptographic decoder for computer programs

1981-09-10

1984-02-21

Cangialosi, Sal

Telegraphy

Systems

Printing

178 2208, H04L 900

Patent

active

044332076

ABSTRACT:
An integrated circuit decoder for providing microcomputer users with access to several proprietary programs selected from a large group of such programs that have been distributed to users in cipher. The decoder chip can decipher a program if an enciphered key called a "permit code" is presented to the decoder chip. Permit codes are not interchangeable between decoders, are issued only to customers that have paid for use of a program product, and each code will work only with one program. As the program is being deciphered in a user's microcomputer, the decoder chip places random errors into the program which make copies of the program malfunction in other microcomputers. The decoder chip keeps a table of addresses where it has placed errors and dynamically corrects the errors on the data bus whenever an error word is addressed during execution. Using such a decoder, thousands of individually priced proprietary software products can be delivered securely to prospective customers in advance of sales on laserdiscs, diskettes, TV-cables, and digital radio broadcasts.

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patent: 4028678 (1977-06-01), Moran
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patent: 4206315 (1980-06-01), Matayas et al.
patent: 4264782 (1981-04-01), Konheim
patent: 4278837 (1981-07-01), Best
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patent: 4319079 (1982-03-01), Best
patent: 4323921 (1982-04-01), Guillou
IBM Tech. Disclosure Bull., vol. 22, No. 2 (7/79) S 9186 0290, Lennon et al., pp. 643-646.
Tuchman, "Integrated System Design" in NBS Special Publication 500-27, pp. 94-96, Feb. 15, 1978.

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