Cryptography – Key management – Having particular key generator
Patent
1993-10-15
1995-10-31
Swann, Tod R.
Cryptography
Key management
Having particular key generator
380 20, 380 15, 380 35, H04N 7167
Patent
active
RE0350788
ABSTRACT:
A technique for encrypting and decrypting information signals normally arranged as a succession of lines of active information, with each line having a line timing reference, such as color video information signals. The active video portion is time shifted with respect to the horizontal sync portion of the corresponding line using a predetermined slowly varying time shifting function. The time shifting information is conveyed to the decryption site by encoding the instantaneous value of the time shifting wave form for the beginning of each field in the vertical blanking portion of that field. To provide a reasonable maximum time shifting range, portions of the trailing edge of the active video in the preceding line and portions of the leading edge of the active video in the current line are discarded. During decryption, the original line timing and color burst signals are discarded and new signals are generated which are time displaced from the active video portion by the original amount before encryption.
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Brill Gerow D.
Macrovision Corporation
Swann Tod R.
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