Software protection device
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United States of America Patent
Stats
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Jan 6, 1987
Grant Date -
N/A
app pub date -
Aug 23, 1985
filing date -
Aug 23, 1984
priority date (Note) -
Expired
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Abstract
In order to prevent the unauthorized copying of software, a software module is encrypted using the data encryption standard (DES) algorithm, and the key is encrypted using the public key of a public/private key algorithm. To use the module it is entered into a software protection device where the private key held in a RAM 11 is used by a processor 13 to decode the DES key using instructions held in a ROM 12. Further instructions held by this ROM are used by the processor 13 to decode the module. Once the process of decoding keys and software has started, the processor 13 runs through a sequence of predetermined instructions and cannot be interrupted (except by switching off). When the sequence is complete processor 13, or for example a host computer 30, is enabled to use the decoded software, but a switch/reset circuit 17 operates preventing access to the RAM 11 and the ROM 12 so preserving the secrecy of the private key and any decoded DES key which is now stored in the RAM 11.
First Claim
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- 15 United States
- 10 France
- 8 Japan
- 7 China
- 5 Korea
- 2 Other
Patent Owner(s)
Patent Owner | Address | |
---|---|---|
BRITISH TECHNOLOGY GROUP LIMITED | 101 NEWINGTON CAUSEWAY LONDON SE1 6BU |
International Classification(s)
Inventor(s)
Inventor Name | Address | # of filed Patents | Total Citations |
---|---|---|---|
Chorley, Bernard J | Hampton, GB2 | 1 | 286 |
Elsom, Simon M | Feltham, GB2 | 1 | 286 |
Parkin, Graeme I P | London, GB2 | 1 | 286 |
Wichmann, Brian A | Woking, GB2 | 1 | 286 |
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Fee | Large entity fee | small entity fee | micro entity fee | due date |
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Fee | Large entity fee | small entity fee | micro entity fee |
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Surcharge after expiration - Late payment is unavoidable | $700.00 | $350.00 | $175.00 |
Surcharge after expiration - Late payment is unintentional | $1,640.00 | $820.00 | $410.00 |
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