US PATENT SUBCLASS 380 / 9
ELECTRIC SIGNAL MODIFICATION (E.G., SCRAMBLING)

Current as of: June, 1999
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380 /   HD   CRYPTOGRAPHY

9ELECTRIC SIGNAL MODIFICATION (E.G., SCRAMBLING) {18}
10  DF  .~> Video {10}
21  DF  .~> Having transmission or distribution of key signal
22  DF  .~> With magnetic record carrier (e.g., tape, drum)
23  DF  .~> With user or record actuated authentication {2}
26  DF  .~> With mechanical control of signal encryption (e.g., cam) {1}
28  DF  .~> By particular algorithmic function encoding {2}
31  DF  .~> Plural modulation of single carrier {1}
33  DF  .~> Using plural paths or channels {1}
35  DF  .~> Variable time delay modulation
36  DF  .~> Time segment interchange {1}
38  DF  .~> Frequency shift or inversion {1}
40  DF  .~> With plural band pass filters
41  DF  .~> With quantizing and subsequent normalizing of signal (e.g., reentry telephone circuitry)
42  DF  .~> Data stream/substitution enciphering {2}
48  DF  .~> With particular synchronization or initiation
49  DF  .~> With digital signal handling (e.g., digital control, digital computer communication) {1}
51  DF  .~> With production of printed copy (e.g., printer, typewriter)
52  DF  .~> Including particular structure or housing (e.g., display, keyboard) {1}

DEFINITION

Classification: 380/9

ELECTRIC SIGNAL MODIFICATION (E.G., SCRAMBLING):

(under the class definition) Subject matter which makes an information signal unintelligible by varying a parameter of the information signal.

(1) Note. This and indented subclasses include message signal scrambling, or interchange of letters.

SEE OR SEARCH THIS CLASS, SUBCLASS:

6, for information signal encryption by masking with a second signal.