US Patent Class 380
CRYPTOGRAPHY



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Current as of: June, 1999
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  DF  CLASS NOTES
1  DF  CRYPTANALYSIS
2  DF  EQUIPMENT TEST OR MALFUNCTION INDICATION
3  DF  STORED INFORMATION ACCESS OR COPY PREVENTION
4  DF  .~ Digital data (e.g., software program protection, data encryption)
5  DF  .~ Video
6  DF  ELECTRIC SIGNAL MASKING
7  DF  .~ Video
8  DF  .~ By signal having discrete step amplitude variation
9  DF  ELECTRIC SIGNAL MODIFICATION (E.G., SCRAMBLING)
10  DF  .~ Video
11  DF  .~.~ Variable time delay modulation of baseband video signal
12  DF  .~.~ Carrier phase shift
13  DF  .~.~ Carrier frequency conversion
14  DF  .~.~ Nonstandard scan of video information
15  DF  .~.~ By modifying synchronizing signal
16  DF  .~.~ Record or coin controlled
17  DF  .~.~ Phase inversion of scan line information
18  DF  .~.~ Facsimile
19  DF  .~.~ Encrypting of accompanying audio signal
20  DF  .~.~ Control coding
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
24  DF  .~.~ Electronic funds transfer (e.g., automatic teller)
25  DF  .~.~ Computer
26  DF  .~ With mechanical control of signal encryption (e.g., cam)
27  DF  .~.~ By perforated record
28  DF  .~ By particular algorithmic function encoding
29  DF  .~.~ NBS/DES algorithm
30  DF  .~.~ Public key
31  DF  .~ Plural modulation of single carrier
32  DF  .~.~ Wobbling of carrier
33  DF  .~ Using plural paths or channels
34  DF  .~.~ Plural carrier frequencies
35  DF  .~ Variable time delay modulation
36  DF  .~ Time segment interchange
37  DF  .~.~ Block/data stream enciphering
38  DF  .~ Frequency shift or inversion
39  DF  .~.~ With plural band pass filters
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
43  DF  .~.~ Key sequence signal combined with data signal
44  DF  .~.~ With particular key generator
45  DF  .~.~.~ Multiple key level
46  DF  .~.~.~ Nonlinear (e.g., pseudorandom)
47  DF  .~.~.~ Plural generators
48  DF  .~ With particular synchronization or initiation
49  DF  .~ With digital signal handling (e.g., digital control, digital computer communication)
50  DF  .~.~ Including shift register or memory
51  DF  .~ With production of printed copy (e.g., printer, typewriter)
52  DF  .~ Including particular structure or housing (e.g., display, keyboard)
53  DF  .~.~ Audio transducer mounting or structure
54  DF  BY MODIFYING OPTICAL IMAGE (E.G., TRANSMISSIVE OVERLAY)
55  DF  WITH PRODUCTION OF PRINTED COPY (E.G., CRYPTOGRAPHIC PRINTER OR TYPEWRITER)
56  DF  SELECTIVELY MOVABLE ELEMENT HAVING CODE CHARACTERS
57  DF  .~ Rotatable
58  DF  .~.~ Characters on peripheral surface (e.g., cylinder section)
59  DF  MISCELLANEOUS