| Class Number |
Class Name |
No. of Patents |
| 380/54 |
By modifying optical image (e.g., transmissive overlay) |
360 |
| 380/247 |
Cellular telephone cryptographic authentication |
276 |
| 380/249 |
Initialization |
60 |
| 380/250 |
Usage pattern detection |
41 |
| 380/248 |
Visiting center |
55 |
| 380/255 |
Communication system using cryptography |
322 |
| 380/257 |
Circuit switched network (e.g., wired telephone) |
103 |
| 380/41 |
Having quantizing and subsequent normalizing of signal (e.g., reentry telephone circuitry) |
40 |
| 380/267 |
Correcting for random appearance of control character code |
25 |
| 380/42 |
Data stream/substitution enciphering |
248 |
| 380/43 |
Key sequence signal combined with data signal |
282 |
| 380/256 |
Fiber optic network |
97 |
| 380/38 |
Frequency shift or inversion |
64 |
| 380/39 |
Having plural band pass filters |
30 |
| 380/269 |
Having compression |
110 |
| 380/40 |
Having plural band pass filters |
28 |
| 380/258 |
Position dependent or authenticating |
127 |
| 380/268 |
Pseudo-random sequence scrambling |
223 |
| 380/275 |
Speech scrambler detail |
76 |
| 380/276 |
Including sampling |
52 |
| 380/259 |
Symmetric key cryptography |
206 |
| 380/265 |
Combining outputs of shift register |
90 |
| 380/266 |
Including a modem |
63 |
| 380/264 |
Key derived from addressable memory element |
89 |
| 380/260 |
Symmetric key synchronization |
131 |
| 380/261 |
Including frame synchronization |
94 |
| 380/263 |
Nonlinear or chaotic system |
81 |
| 380/262 |
Transmitting a seed, sequence, or initial value |
261 |
| 380/36 |
Time segment interchange |
67 |
| 380/37 |
Block/data stream enciphering |
366 |
| 380/35 |
Variable time delay modulation |
51 |
| 380/270 |
Wireless communication |
458 |
| 380/271 |
Having receiver selection (e.g., pager) |
71 |
| 380/272 |
Including hand-off based cryptographic alteration |
40 |
| 380/31 |
Plural modulation of single carrier |
40 |
| 380/32 |
Wobbling of carrier |
9 |
| 380/273 |
Rekeying system |
127 |
| 380/274 |
Synchronization |
115 |
| 380/33 |
Using plural paths or channels |
129 |
| 380/34 |
Plural carrier frequencies |
431 |
| 380/1 |
Cryptanalysis |
52 |
| 380/252 |
Electric signal masking |
124 |
| 380/253 |
By signal having discrete frequency component |
33 |
| 380/254 |
By signal having discrete step amplitude variation |
20 |
| 380/287 |
Electric signal modification |
80 |
| 380/22 |
Having magnetic record carrier (e.g., tape, drum) |
68 |
| 380/26 |
Having mechanical control of signal encryption (e.g., cam) |
25 |
| 380/27 |
By perforated record |
9 |
| 380/51 |
Having production of printed copy (e.g., printer, typewriter) |
295 |
| 380/52 |
Including particular structure or housing (e.g., display, keyboard) |
148 |
| 380/53 |
Audio transducer mounting or structure |
9 |
| 380/251 |
Electronic game using cryptography |
59 |
| 380/2 |
Equipment test or malfunction indication |
128 |
| 380/243 |
Facsimile cryptography |
125 |
| 380/246 |
Including generation of an associated coded record |
41 |
| 380/245 |
Nonstandard scan pattern |
11 |
| 380/244 |
Synchronization |
9 |
| 380/55 |
Having production of printed copy (e.g., cryptographic printer or typewriter) |
136 |
| 380/277 |
Key management |
814 |
| 380/44 |
Having particular key generator |
642 |
| 380/45 |
Multiple key level |
240 |
| 380/46 |
Nonlinear (e.g., pseudorandom) |
608 |
| 380/47 |
Plural generators |
182 |
| 380/278 |
Key distribution |
399 |
| 380/279 |
Key distribution center |
213 |
| 380/282 |
By public key method |
256 |
| 380/280 |
Control vector or tag |
73 |
| 380/281 |
Using master key (e.g., key-encrypting-key) |
248 |
| 380/283 |
User-to-user key distributed over data link (i.e., no center) |
248 |
| 380/285 |
By public key method |
193 |
| 380/284 |
Using master key (e.g., key-encrypting-key) |
147 |
| 380/286 |
Key escrow or recovery |
217 |
| 380/59 |
Miscellaneous |
159 |
| 380/28 |
Particular algorithmic function encoding |
971 |
| 380/29 |
Nbs/des algorithm |
335 |
| 380/30 |
Public key |
1033 |
| 380/56 |
Selectively movable element having code characters |
25 |
| 380/57 |
Rotatable |
14 |
| 380/58 |
Characters on peripheral surface (e.g., cylinder section) |
5 |
| 380/200 |
Video cryptography |
251 |
| 380/201 |
Copy protection or prevention |
679 |
| 380/203 |
Having copy protect signal |
313 |
| 380/202 |
Having origin or program id |
200 |
| 380/204 |
Modifying sync signal |
106 |
| 380/205 |
Video electric signal masking |
74 |
| 380/208 |
Including filter for removing masking signal |
40 |
| 380/207 |
Including locally generated masking signal |
30 |
| 380/206 |
Masking of synchronization signal |
39 |
| 380/209 |
Masking signal selectively addressed |
42 |
| 380/210 |
Video electric signal modification (e.g., scrambling) |
263 |
| 380/221 |
By modifying synchronizing signal |
71 |
| 380/222 |
Including phase inversion of scan line information |
30 |
| 380/224 |
Including pseudo-synchronizing pulse |
30 |
| 380/226 |
Key signal in blanking interval |
60 |
| 380/223 |
Key signal on separate carrier |
59 |
| 380/225 |
Self-synchronizing circuit at receiver |
34 |
| 380/220 |
Carrier frequency conversion |
30 |
| 380/219 |
Carrier phase shift |
23 |
| 380/213 |
Chrominance scrambling |
49 |
| 380/239 |
Encrypted code control signal |
254 |
| 380/216 |
Image data converted to digital before modification |
108 |
| 380/217 |
Having compression (e.g., mpeg) |
150 |
| 380/240 |
Including addressed decoder control signal |
176 |
| 380/242 |
Having command signal for receiver |
117 |
| 380/241 |
Having program id or authorization |
238 |
| 380/211 |
Interactive tv |
98 |
| 380/236 |
Modifying accompanying audio signal |
64 |
| 380/237 |
Including digital audio |
53 |
| 380/238 |
Including frequency modification of audio signal or frequency shifting of audio carrier |
41 |
| 380/214 |
Nonstandard scan pattern of video information |
38 |
| 380/215 |
Line cut and shuffle |
57 |
| 380/235 |
Phase inversion of scan line information |
41 |
| 380/212 |
Plural video stream multiplexing |
118 |
| 380/227 |
Record or coin controlled |
72 |
| 380/229 |
Including authentication |
91 |
| 380/228 |
Including key on record |
116 |
| 380/230 |
Including usage recording |
55 |
| 380/231 |
Usage or charge determination |
130 |
| 380/232 |
Including authentication |
95 |
| 380/234 |
Including display of supplemental information |
40 |
| 380/233 |
Including usage or charge recording at subscriber station |
56 |
| 380/218 |
Variable time delay modulation of baseband video signal |
36 |
