| Subclass
| Subclass Name
| # of Patents
|
| 1 |
CRYPTANALYSIS |
44 |
| 2 |
EQUIPMENT TEST OR MALFUNCTION INDICATION |
114 |
| 200 |
VIDEO CRYPTOGRAPHY |
138 |
| 201 |
Copy protection or prevention |
388 |
| 202 |
Having origin or program ID |
123 |
| 203 |
Having copy protect signal |
203 |
| 204 |
Modifying sync signal |
86 |
| 205 |
Video electric signal masking |
63 |
| 206 |
Masking of synchronization signal |
35 |
| 207 |
Including locally generated masking signal |
26 |
| 208 |
Including filter for removing masking signal |
36 |
| 209 |
Masking signal selectively addressed |
40 |
| 210 |
Video electric signal modification (e.g., scrambling) |
172 |
| 211 |
Interactive TV |
78 |
| 212 |
Plural video stream multiplexing |
101 |
| 213 |
Chrominance scrambling |
41 |
| 214 |
Nonstandard scan pattern of video information |
31 |
| 215 |
Line cut and shuffle |
55 |
| 216 |
Image data converted to digital before modification |
87 |
| 217 |
Having compression (e.g., MPEG) |
111 |
| 218 |
Variable time delay modulation of baseband video signal |
32 |
| 219 |
Carrier phase shift |
20 |
| 220 |
Carrier frequency conversion |
29 |
| 221 |
By modifying synchronizing signal |
65 |
| 222 |
Including phase inversion of scan line information |
29 |
| 223 |
Key signal on separate carrier |
55 |
| 224 |
Including pseudo-synchronizing pulse |
27 |
| 225 |
Self-synchronizing circuit at receiver |
30 |
| 226 |
Key signal in blanking interval |
55 |
| 227 |
Record or coin controlled |
57 |
| 228 |
Including key on record |
81 |
| 229 |
Including authentication |
42 |
| 230 |
Including usage recording |
27 |
| 231 |
Usage or charge determination |
87 |
| 232 |
Including authentication |
55 |
| 233 |
Including usage or charge recording at subscriber station |
40 |
| 234 |
Including display of supplemental information |
28 |
| 235 |
Phase inversion of scan line information |
39 |
| 236 |
Modifying accompanying audio signal |
58 |
| 237 |
Including digital audio |
43 |
| 238 |
Including frequency modification of audio signal or frequency shifting of audio carrier |
38 |
| 239 |
Encrypted code control signal |
199 |
| 240 |
Including addressed decoder control signal |
154 |
| 241 |
Having program ID or authorization |
218 |
| 242 |
Having command signal for receiver |
101 |
| 243 |
FACSIMILE CRYPTOGRAPHY |
108 |
| 244 |
Synchronization |
5 |
| 245 |
Nonstandard scan pattern |
8 |
| 246 |
Including generation of an associated coded record |
33 |
| 247 |
CELLULAR TELEPHONE CRYPTOGRAPHIC AUTHENTICATION |
187 |
| 248 |
Visiting center |
45 |
| 249 |
Initialization |
47 |
| 250 |
Usage pattern detection |
29 |
| 251 |
ELECTRONIC GAME USING CRYPTOGRAPHY |
44 |
| 252 |
ELECTRIC SIGNAL MASKING |
101 |
| 253 |
By signal having discrete frequency component |
32 |
| 254 |
By signal having discrete step amplitude variation |
19 |
| 255 |
COMMUNICATION SYSTEM USING CRYPTOGRAPHY |
219 |
| 256 |
Fiber optic network |
66 |
| 257 |
Circuit switched network (e.g., wired telephone) |
94 |
| 41 |
Having quantizing and subsequent normalizing of signal (e.g., reentry telephone circuitry) |
37 |
| 258 |
Position dependent or authenticating |
87 |
| 259 |
Symmetric key cryptography |
150 |
| 260 |
Symmetric key synchronization |
105 |
| 261 |
Including frame synchronization |
85 |
| 262 |
Transmitting a seed, sequence, or initial value |
203 |
| 263 |
Nonlinear or chaotic system |
49 |
| 264 |
Key derived from addressable memory element |
65 |
| 265 |
Combining outputs of shift register |
72 |
| 266 |
Including a modem |
53 |
| 267 |
Correcting for random appearance of control character code |
23 |
| 268 |
Pseudo-random sequence scrambling |
160 |
| 269 |
Having compression |
88 |
| 270 |
Wireless communication |
294 |
| 271 |
Having receiver selection (e.g., pager) |
55 |
| 272 |
Including hand-off based cryptographic alteration |
25 |
| 273 |
Rekeying system |
103 |
| 31 |
Plural modulation of single carrier |
35 |
| 32 |
Wobbling of carrier |
9 |
| 33 |
Using plural paths or channels |
110 |
| 34 |
Plural carrier frequencies |
417 |
| 274 |
Synchronization |
98 |
| 35 |
Variable time delay modulation |
42 |
| 36 |
Time segment interchange |
55 |
| 37 |
Block/data stream enciphering |
263 |
| 38 |
Frequency shift or inversion |
59 |
| 39 |
Having plural band pass filters |
28 |
| 40 |
Having plural band pass filters |
24 |
| 42 |
Data stream/substitution enciphering |
184 |
| 43 |
Key sequence signal combined with data signal |
248 |
| 275 |
Speech scrambler detail |
69 |
| 276 |
Including sampling |
49 |
| 277 |
KEY MANAGEMENT |
527 |
| 278 |
Key distribution |
244 |
| 279 |
Key distribution center |
154 |
| 280 |
Control vector or tag |
51 |
| 281 |
Using master key (e.g., key-encrypting-key) |
183 |
| 282 |
By public key method |
168 |
| 283 |
User-to-user key distributed over data link (i.e., no center) |
186 |
| 284 |
Using master key (e.g., key-encrypting-key) |
92 |
| 285 |
By public key method |
140 |
| 286 |
Key escrow or recovery |
173 |
| 44 |
Having particular key generator |
454 |
| 45 |
Multiple key level |
183 |
| 46 |
Nonlinear (e.g., pseudorandom) |
512 |
| 47 |
Plural generators |
154 |
| 28 |
PARTICULAR ALGORITHMIC FUNCTION ENCODING |
736 |
| 29 |
NBS/DES algorithm |
281 |
| 30 |
Public key |
859 |
| 287 |
ELECTRIC SIGNAL MODIFICATION |
69 |
| 22 |
Having magnetic record carrier (e.g., tape, drum) |
60 |
| 26 |
Having mechanical control of signal encryption (e.g., cam) |
23 |
| 27 |
By perforated record |
8 |
| 51 |
Having production of printed copy (e.g., printer, typewriter) |
254 |
| 52 |
Including particular structure or housing (e.g., display, keyboard) |
139 |
| 53 |
Audio transducer mounting or structure |
9 |
| 54 |
BY MODIFYING OPTICAL IMAGE (E.G., TRANSMISSIVE OVERLAY) |
303 |
| 55 |
HAVING PRODUCTION OF PRINTED COPY (E.G., CRYPTOGRAPHIC PRINTER OR TYPEWRITER) |
122 |
| 56 |
SELECTIVELY MOVABLE ELEMENT HAVING CODE CHARACTERS |
23 |
| 57 |
Rotatable |
14 |
| 58 |
Characters on peripheral surface (e.g., cylinder section) |
5 |
| 59 |
MISCELLANEOUS |
151 |
