Cryptography – Key management – Having particular key generator
Patent
1997-06-27
1998-10-27
Tarcza, Thomas H.
Cryptography
Key management
Having particular key generator
380 4, 380 9, 369 59, 360 60, 341 58, H04L 900, H04K 102, H04K 104, G11B 1504, G11B 1904, H04N 576, H03M 700
Patent
active
058287540
ABSTRACT:
A method of inhibiting copying of digital data. In a first embodiment, a sequence of symbols is added to original data, the sequence of symbols selected to encode into channel bits having a large accumulated digital sum variance. The sequence of symbols is then encoded by a special encoder that generates special channel bits that don't have a large accumulated digital sum variance. The special channel bits may be unambiguously decoded, but the resulting decoded symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a second embodiment, a single symbol in the sequence of symbols is replaced after error correction symbols have been added. The sequence of symbols with one substituted symbol is encoded into channel bits that don't have a large accumulated digital sum variance. The resulting channel bits may be unambiguously decoded but the resulting symbol sequence will be error corrected and the error corrected symbol sequence will likely be reencoded into channel bits having a large accumulated digital sum variance. In a third embodiment, additional decryption or descrambling information or other data modification information is encoded into the sign of the digital sum variance of each blocked row of data. The decoded additional information is used to decrypt, descramble or otherwise modify the primary information. In an alternative third embodiment, decryption information is encoded into patterns of run lengths. In general, the embodiments and alternatives are independent and can be combined in complex ways to make reencoding difficult.
REFERENCES:
patent: 4603413 (1986-07-01), Sinjou et al.
Hewlett--Packard Company
Sayadian Hrayr A.
Tarcza Thomas H.
Winfield Augustus W.
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