SUBJECT MATTER UNDER THIS CLASS:
This class includes equipment and processes which (a) conceal or obscure intelligible information by transforming such information so as to make the information unintelligible to a casual or unauthorized recipient, or (b) extract intelligible information from such a concealed representation, including breaking of unknown codes and messages.
(1) Note. cryptographic processing may include, e.g., scrambling or masking or their complementary transformations.
(2) Note. All electrical communications equipment which processes an information signal for purposes of concealment are classified in this class.
(3) Note. Processing or converting of a signal for purposes of handling or transmission which may incidentally render a signal unintelligible are not classified in this class.
(4) Note. Mere blocking of access to the information is not considered a cryptographic transformation of the signal or information.
(5) Note. A cryptogram or a cryptographic record absent a separate encrypting or decrypting device is classified elsewhere. See References to Other Classes, below.
(6) Excluded herein is nominal cryptography in combination with subject matter of another class. Such subject matter is classified with the other class. See search notes below.
(7) Excluded herein is subject matter of this class in combination with the specific environments of a) business data processing or b) electrical computer or digital processing system support. Such subject matter is classified elsewhere in the classes providing for the specific environment. See search notes below.
(8) During the latest reclassification project, a group of existing subclasses were repositioned as is pending additional reclassification of this class. However, screening was not done within this group of subclasses or between this group and the other subclasses not part of the latest project. This should be taken into consideration when determining an appropriate field of search.

REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:
178, Telegraphy, subclass 37 for a private printing recorder; subclass 99.1 for an acoustically shielded sounder.
235, Registers, subclass 495 for a perforated, coded record (e.g., punched card or tape) reading template.
283, Printed Matter, subclass 73 for a printed or embossed article absent decryption structure.
341, Coded Data Generation or Conversion, 20 and 173+, for code transmission, and 50+ for code conversion not specified as a concealing or cryptographic coding method.
342, Communications: Directive Radio Wave Systems and Devices (e.g., Radar, Radio Navigation), 13 for radar electronic warfare; subclasses 42+ for a radar transponder identification system.
348, Television, subclass 5.5 for unauthorized use control of television equipment by signal access blocking.
379, Telephonic Communications, 188 for telephone use or access blocking equipment.
381, Electrical Audio Signal Processing Systems and Devices, subclass 73.1 for electrically operated sound or noise masking.
395, Information Processing System Organization, subclass 728
for generalized access blocking less cryptographic means or function.
399, Electrophotography, subclass 12 for unit or part identification, subclass 84 for key sheet controlling job mode, and subclasses 366+ for document handling of unauthorized copy prevention.
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclasses 50-80 for business processing using cryptography and foreign art collection FOR 124 for cryptographic protection of electronic funds transfer.
709, Electrical Computers and Digital Data Processing Systems: Multiple Computer or Process Coordinating, 200 for data transferring among multiple computer and digital processing systems.
711, Electrical Computers and Digital Processing Systems: Memory, 163 for memory access limiting less cryptographic means or function.
713, Electrical Computers and Digital Processing Systems: Support, subclasses 150-194 for cryptographic electrical computer or digital processing system support, subclasses 200+ for security in digital processing systems, and foreign art collections FOR 123 and FOR 125 for cryptographic user or record authentication.
714, Error Detection/Correction and Fault Detection/Recovery, appropriate subclasses for generic error checking of digital devices.

GLOSSARY:
CIPHER
Information concealed by substitution or interchange of text characters for those in the original message.
CODE
Information concealed by substitution of words or symbols for words of the concealed message.
CRYPTOGRAPHY
The study of secret information storage or communication.
CRYPTANALYSIS
Determination of encryption code of encrypted message (i.e., codebreaking).
DECRYPTING OR DECIPHERING
A process of extracting concealed information from an intentionally obscured form and changing it into a form intelligible to a recipient with proper authorization or equipment.
ENCRYPTING OR ENCIPHERING
A process of obscuring information by intentionally changing it to a form unintelligible to a casual or unauthorized observer.
KEY
A formula, word or signal used to define the code in encryption or decryption of the information. Such a signal is often a digital signal having a predetermined or pseudorandom content.

CRYPTANALYSIS:
This subclass is indented under the class definition. Subject matter which includes breaking of a secret code or cipher.
(1) Note. After the code has been broken, use of the code for reception is classified elsewhere in this class.

EQUIPMENT TEST OR MALFUNCTION INDICATION:
This subclass is indented under the class definition. Subject matter for evaluating or monitoring the condition of cryptographic equipment or equipment associated with a cryptographic system.
(1) Note. Associated equipment includes testing or monitoring of diverse equipment (e.g. communication or display equipment) which would be classified in either the class providing for the particular equipment or in a testing class absent association with cryptographic equipment.

SEE OR SEARCH CLASS:
324, Electricity: Measuring and Testing, appropriate subclasses for electrical measuring and testing of general utility.
375, Pulse or Digital Communications, 224 for testing or
pulse or digital communications equipment.

Having magnetic record carrier (e.g., tape, drum):
This subclass is indented under subclass 9. Subject matter utilizing storage on or retrieval from a moving magnetic element for encoding the signal.
(1) Note. The moving element is often an elongate web.

SEE OR SEARCH CLASS:
360, Dynamic Magnetic Information Storage or Retrieval, subclass 7 and 8+ for delay, and for modification, respectively, of an electrical signal by recording and subsequent retrieval from a magnetic record medium.
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclass 57 and 58 for preventing access to or copying of stored information in a distributed data file.

With user or record actuated authentication:
This subclass is indented under subclass 9. Subject matter which encrypts a signal indicating proper authorization of an individual or validity of a record for operating a device.
(1) Note. The subject matter of the classifications referred to in the following search notes are classified in this class (380) if encryption or encrypting equipment is included therein.

SEE OR SEARCH CLASS:
235, Registers, 375 for a coded record operated system, absent signal encryption.
340, Communications: Electrical, 825.31 for electrical selective authorization control; subclass 825.34 for selective electrical authentication.
379, Telephonic Communications, 91.01 for credit authorization, other than verbal, by telephone; subclasses 102.01+ for remote control by telephone.
399, Electrophotography, subclass 12 for unit or part identification, subclass 84 for key sheet controlling job mode, and subclasses 366+ for document handling of
unauthorized copy prevention..

Electronic funds transfer (e.g., automatic teller):
This subclass is indented under subclass 23. Subject matter which encrypts a signal for authorization, or authorization request (e.g., password), for credit or debit of funds to a customer's account.

SEE OR SEARCH CLASS:
221, Article Dispensing, appropriate subclasses for currency dispensing structure, absent signal encryption.
235, Registers, subclass 379 for a coded record actuated banking system; subclasses 380+ for a coded record operated credit system, absent signal encryption.
340, Communications: Electrical, subclass 825.33 for an intelligence comparing credit system, absent signal encryption.
379, Telephonic Communication, 91.01 for automatic credit authorization over a telephone line absent signal encryption.
705, Data Processing: Financial, Business Practice, Management, or Cost/price Determination, subclass 18 for an electronic cash register having cryptography; subclass 44 for a general funds transfer or credit transaction requiring authorization or authentication not including a cryptographic limitation.

Computer:
This subclass is indented under subclass 23. Subject matter which encrypts and transmits authorization for access to computing or data processing equipment.

SEE OR SEARCH CLASS:
364, Electrical Computers and Data Processing Systems, appropriate subclasses for computer access authorization absent encryption.
379, Telephonic Communications, 93.02 for computer access restriction over a telephone line absent encryption.
705, Data Processing: Financial, Business Practice,
Management, or Cost/price Determination, 18 for a business management data processing system not including a cryptographic limitation.

Having mechanical control of signal encryption (e.g., cam):
This subclass is indented under the subclass definition. Subject matter including an electrical element controlled by the motion of physical configuration of a solid object.
(1) Note. The device in this subclass generally use a mechanically varying element as a cryptographic key.
(2) Note. Included herein are cam controlled elements.

By perforated record:
This subclass is indented under subclass 26. Subject matter which controls cryptographic signal modification in accordance with a pattern of openings along the length of an elongate web.
(1) Note. The elongate web may be a movable strip.
(2) Note. The pattern of perforations may supply the encryption key.

By particular algorithmic function encoding:
This subclass is indented under the class definition. Subject matter wherein an algorithmic operation is performed upon a signal in order to encrypt the information signal.
(1) Note. The processed signal may be the message signal.

SEE OR SEARCH CLASS:
708, Electrical Computers: Arithmetic Processing and Calculating, appropriate subclasses for a computer which performs a mathematical transformation.

NBS/DES algorithm:
This subclass is indented under subclass 28. Subject matter which encrypts a digital signal by a sequence including an initial 64-bit permutation, a 56-bit encryption-key dependent substitution block computation, and an inversion of the initial permutation.
(1) Note. The details of this encryption algorithm are published in the U.S. Government standard: Federal Information Processing Standard (FIPS) publication No. 46, January 15, 1977, U.S. National Bureau of Standards.

Public key:
This subclass is indented under subclass 28. Subject matter including an encryption algorithm which is computationally infeasible to invert, and having distinct encryption and decryption keys.
(1) Note. The encryption keys do not require secrecy and are usually published.

Plural modulation of single carrier:
This subclass is indented under subclass 270. Subject matter which modulates a carrier with more than one signal or varies more than one signal parameter.
(1) Note. The additional signal may be scrambling signal or another information signal.

SEE OR SEARCH CLASS:
370, Multiplex Communications, subclass 204 for multiplexing by plural forms of modulation; subclasses 343+ and 480+ for combining or distributing information via frequency channels.
381, Electrical Audio Signal Processing Systems and Devices, 4 for stereophonic signal broadcasting using an AM receiver.
455, Telecommunications, subclass 61 for a carrier wave system using plural modulation for a signal message absent cryptographic equipment.

Wobbling of carrier:
This subclass is indented under subclass 31. Subject matter which varies the frequency of an information modulated carrier signal periodically over a definite range.

Using plural paths or channels:
This subclass is indented under subclass 270. Subject matter which transmits an information signal or a portion thereof over different communications links simultaneously, serially, or alternately.
(1) Note. This subclass includes an alternate nonencrypted communications path.

SEE OR SEARCH CLASS:
340, Communications: Electrical, 825.03 for selective communication channel selection, absent encryption.
379, Telephonic Communications, 242 for selective switching of a nonencrypted telephone circuit.

Plural carrier frequencies:
This subclass is indented under subclass 33. Subject matter which transmits different composite parts of an information signal over carrier waves of different frequencies.

SEE OR SEARCH CLASS:
455, Telecommunications, subclass 59 for a system which transmits a signal message over plural carrier waves absent message concealment.

Variable time delay modulation:
This subclass is indented under subclass 9. Subject matter which applies varying amounts of time delay to the information signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
36 for encryption by time segment interchange.

SEE OR SEARCH CLASS:
332, Modulators, 144 for phase modulation by an information signal.

Time segment interchange:
This subclass is indented under subclass 9. Subject matter which divides the message signal into time interval segments the order of which are interchanged.
(1) Note. Excluded herein is this subject matter which involves a magnetic record carrier. Such subject matter is classified with electric signal modification by magnetic record carrier. See search notes below.

SEE OR SEARCH THIS CLASS, SUBCLASS:
22 for this subject matter which interchanges time segments by use of a magnetic record carrier.

Block/data stream enciphering:
This subclass is indented under subclass 36. Subject matter wherein time interchanged data segments are processed either in discrete blocks, or a continuous stream, of bits or pulses which serially comprise the message stream.

Frequency shift or inversion:
This subclass is indented under subclass 255. Subject matter which modifies a segment of the frequency spectrum of the information signal.

SEE OR SEARCH CLASS:
370, Multiplex Communications, 343 and 480+ for combining or distributing information via frequency channels, absent cryptography.
375, Pulse or Digital Communications, 240 for bandwidth compression or expansion to facilitate digital signal
handling, rather than conceal information.
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression, 500 for audio signal bandwidth compression or expansion for purposes other than concealment of information.

Having plural band pass filters:
This subclass is indented under subclass 38. Subject matter which divides the signal into a plurality of subbands by filtering prior to a frequency shift or inversion.

Having plural band pass filters:
This subclass is indented under subclass 255. Subject matter which divides the signal into a plurality of subbands by filtering prior to further encryption.

Having quantizing and subsequent normalizing of signal (e.g., reentry telephone circuitry):
This subclass is indented under subclass 257. Subject matter wherein the message signal amplitude is divided into discrete amplitude ranges which are subsequently weighted and combined.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclass 200 for quantizing of an analog signal.
375, Pulse or Digital Communications, appropriate subclasses for pulse code modulation equipment.

Data stream/substitution enciphering:
This subclass is indented under subclass 255. Subject matter which encrypts a message signal composed of a stream of data elements serially and continuously to produce a stream of the corresponding encrypted data elements.
(1) Note. The encryption may be performed by either modification of substitution of the data stream elements.

SEE OR SEARCH THIS CLASS, SUBCLASS:
37 for this subject matter combined with time segment interchange.

Key sequence signal combined with data signal:
This subclass is indented under subclass 42. Subject matter wherein a predetermined sequence of digital signals is combined element-for-element with the message signal data elements to produce an encrypted or decrypted signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
278 and 279 - 285 for distribution of the key signal.

Having particular key generator:
This subclass is indented under subclass 277. Subject matter including a detail of a predetermined digital sequence signal generator.

SEE OR SEARCH CLASS:
331, Oscillators, subclass 78 for a random oscillator.
708, Electrical Computers: Arithmetic Processing and Calculating, 250 for a random digital signal generator.

Multiple key level:
This subclass is indented under subclass 44. Subject matter including plural encrypting or decrypting stages each of which has a separate key.

Nonlinear (e.g., pseudorandom):
This subclass is indented under subclass 44. Subject matter wherein the key signal does not vary in a constant or predictable manner.
(1) Note. Included herein is a pseudorandom key signal generator.

Plural generators:
This subclass is indented under subclass 44. Subject matter which includes more than one generator to produce the predetermined signal sequence.

Having production of printed copy (e.g., printer, typewriter):
This subclass is indented under the class definition. Subject matter which generates a permanent visible record of either the encrypted or decrypted characters.

SEE OR SEARCH THIS CLASS, SUBCLASS:
52 for an electrical cryptographic device controlled by a keyboard not limited to a typewriter.
55 for an electrical cryptographic device controlled by a keyboard not limited to a typewriter.
243 and 244 - 246 for reproduction of an optically scanned document image in cryptographic equipment.

SEE OR SEARCH CLASS:
400, Typewriting Machines, subclass 90 for a typewriter having electrical key reassignment without message concealment (e.g., "QWERTY" to "DVORAK" conversion).

Including particular structure or housing (e.g., display, keyboard):
This subclass is indented under the class definition. Subject matter which includes a detail of the configuration or arrangement of the cryptographic equipment of communications equipment connected thereto.
(1) Note. Such equipment may include an enclosure, keyboard display, etc.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, 22 for a keyboard controlled noncryptographic encoding circuit.

Audio transducer mounting or structure:
This subclass is indented under subclass 52. Subject matter including a structural detail or an audio sensing or reproducing transducer or a mounting therefor.

SEE OR SEARCH CLASS:
181, Acoustics, appropriate subclasses for an audio transducer housing.
379, Telephonic Communications, appropriate subclasses for a bidirectional speech circuit or audio terminal, not including cryptographic equipment.
381, Electrical Audio Signal Processing Systems and Devices, 150 for an electrical transducer not connected to cryptographic equipment.

BY MODIFYING OPTICAL IMAGE (E.G., TRANSMISSIVE OVERLAY):
This subclass is indented under the class definition. Subject matter which changes the visible appearance of an object so as to encrypt visible markings, or to decode the appearance of the object into intelligible visible markings.

SEE OR SEARCH CLASS:
283, Printed Matter, subclass 17 and 73 for an object with encrypted information printed or embossed thereon.
359, Optics: Systems (Including Communication) and Elements, appropriate subclasses for optically transmissive elements, particularly 1 for a holographic element; subclasses 619+ for a surface composed of lenticular elements; subclasses 885+ for an optical filter.
399, Electrophotography, subclass 12 for unit or part identification, subclass 84 for key sheet controlling job mode, and subclasses 366+ for document handling of unauthorized copy prevention.

HAVING PRODUCTION OF PRINTED COPY (E.G., CRYPTOGRAPHIC PRINTER OR TYPEWRITER):
This subclass is indented under the class definition. Subject matter which generates a permanent visible record of either the encrypted or decrypted characters.

SEE OR SEARCH CLASS:
400, Typewriting Machines, 89 for a typewriter having key reassignment without message concealment (e.g., "QWERTY" to "DVORAK" conversion).

SELECTIVELY MOVABLE ELEMENT HAVING CODE CHARACTERS:
This subclass is indented under the class definition. Subject matter for encrypting a message signal which is composed of distinct intelligible characters which are visibly positioned on relatively movable surfaces to enable transposing or substituting such characters.
(1) Note. The term "character" is intended to mean at least a distinct intelligible element, but also includes phrases, numbers, etc., as the intelligence bearing or the encrypted message

Rotatable:
This subclass is indented under subclass 56. Subject matter wherein adjacent movable character bearing surfaces have a circular motion component.

Characters on peripheral surfaces (e.g., cylinder section):
This subclass is indented under subclass 57. Subject matter wherein the character bearing surface is on an edge surface of a movable element.

SEE OR SEARCH CLASS:
399, Electrophotography, subclass 12 for unit or part identification, subclass 84 for key sheet controlling job mode, and subclasses 366+ for document handling of unauthorized copy prevention.

MISCELLANEOUS:
This subclass is indented under the class definition. Subject matter not provided for in any of the preceding subclasses.

VIDEO CRYPTOGRAPHY:
Subject matter wherein a video signal representative of a time varying object or image is made unintelligible.
(1) Note. Processing of a picture signal representing a static image is classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:
243 for facsimile cryptography.

SEE OR SEARCH CLASS:
348, Television, appropriate subclasses for television processing absent encryption.
358, Facsimile, appropriate subclasses for facsimile equipment absent signal encryption.

Copy protection or prevention:
This subclass is indented under 200. Subject matter which prevents rerecording of a stored picture signal representative of a time varying object or image.

SEE OR SEARCH CLASS:
360, Dynamic Magnetic Information Storage or Retrieval, subclass 60 for recording or erasing prevention.
369, Dynamic Information Storage or Retrieval, subclass 84 and 85 for dynamic record rerecording.
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclass 57 and 58 for copy protection or prevention of distributed data files.

Having origin or program ID:
This subclass is indented under 201. Subject matter wherein a video signal which is copy protected is supplemented by a unique identifier of a source or picture signal.

Having copy protect signal:
This subclass is indented under 201. Subject matter wherein a video signal which is copy protected is supplemented by a separate signal indicating a protection mode.

Modifying sync signal:
This subclass is indented under 201. Subject matter wherein the signal for proper timing of a dynamic playback system is altered.

SEE OR SEARCH THIS CLASS, SUBCLASS:
221 for generic video sync modification.

Video electric signal masking:
This subclass is indented under 200. Subject matter wherein the characteristics of an information bearing video electric signal are obscured by the addition of an extraneous interfering signal.
(1) Note. Obscuring of a video display by an optical overlay is classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:
54 for modifying an optical image by an overlay.
252 253, and 254 for electric signal masking in general.

Masking of synchronization signal:
This subclass is indented under 205. Subject matter wherein the interfering signal is combined with the video electric signal to obscure a scanning time component.

SEE OR SEARCH THIS CLASS, SUBCLASS:
221 for generic video sync modification.

Including locally generated masking signal:
This subclass is indented under 205. Subject matter wherein the masking signal is produced and added at or near a receiver.

Including filter for removing masking signal:
This subclass is indented under 205. Subject matter wherein an electronic circuit eliminates the interfering signal.

SEE OR SEARCH CLASS:
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, or Systems, subclass 552 for active filters.
333, Wave Transmission Lines and Networks, subclasses 167-185 for passive filters.
708, Electrical Computers: Arithmetic Processing and Calculating, 300 for filtering by digital computer and subclass 819 for filtering by analog calculating computer.

Masking signal selectively addressed:
This subclass is indented under 205. Subject matter
wherein an interfering signal is directed to a particular subscriber.

SEE OR SEARCH THIS CLASS, SUBCLASS:
240 for an addressed scrambling decoder control signal.

Video electric signal modification (e.g., scrambling):
This subclass is indented under 200. Subject matter wherein a video electric signal is made unintelligible by varying at least one of its parameters.
(1) Note. The electric signal may be analog or digital.
(2) Note. The modification may include such operations as transposition.
(3) Note. The parameter may include a synchronization component.

SEE OR SEARCH THIS CLASS, SUBCLASS:
287 through 53 for modification (e.g., scrambling) of an electric signal in general.

Interactive TV:
This subclass is indented under 210. Subject matter including two-way communication with a TV signal source.

SEE OR SEARCH CLASS:
348, Television, subclasses 13-20 for two-way (e.g., interactive) television absent cryptography.

Plural video stream multiplexing:
This subclass is indented under 210. Subject matter wherein multiple video streams are combined into a single video stream

SEE OR SEARCH CLASS:
370, Multiplex Communications, appropriate subclasses for multiplexing in general.

Chrominance scrambling:
This subclass is indented under 210. Subject matter wherein the portion of a video signal which conveys color information is modified.

SEE OR SEARCH CLASS:
348, Television, subclasses 571-721 for chrominance signal processing in general.

Nonstandard scan pattern of video information:
This subclass is indented under 210. Subject matter wherein the normal ordering of the scan components is modified.
(1) Note. Examples of a nonstandard scan pattern are: nonadjacent scan lines, oppositely directed scan lines, or nonsequential video information in standard scan line.
(2) Note. Scan components are: line segments, lines, fields, and frames.

SEE OR SEARCH THIS CLASS, SUBCLASS:
222 for a modified sync signal having phase inversion of scan line information.
235 for phase inversion of scan line information.
245 for a facsimile nonstandard scan pattern.

Line cut and shuffle:
This subclass is indented under 214. Subject matter wherein an individual scan line is segmented and then the order of the segments is rearranged.

Image data converted to digital before modification:
This subclass is indented under 210. Subject matter wherein a baseband video signal is digitized prior to signal modification.

Having compression (e.g., MPEG):
This subclass is indented under 216. Subject matter wherein the quantity of data representing the converted image data is reduced prior to further processing.

SEE OR SEARCH THIS CLASS, SUBCLASS:
269 for cryptographic communication system having compression.

SEE OR SEARCH CLASS:
348, Television, subclasses 384-440 for television with bandwidth reduction.
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression, subclass 503 and 504 for audio signal time compression or expansion.
708, Electrical Computers: Arithmetic Processing and Calculating, subclass 203 for compression/decompression by digital computer.

Variable time delay modulation of baseband video signal:
This subclass is indented under 210. Subject matter which modifies a picture signal before carrier modulation by application of varying amounts of time delay.
(1) Note. This and indented subclasses also include time shifting between video information and synchronizing signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
35 for encryption of other than picture signals by variable time delay modulation.

Carrier phase shift:
This subclass is indented under 210. Subject matter in which a picture signal modulated onto a carrier wave is modified by a phase change of the carrier.

Carrier frequency conversion:
This subclass is indented under 210. Subject matter under subclass 210 in which the frequency of a carrier wave is modified for encryption.

SEE OR SEARCH THIS CLASS, SUBCLASS:
38 and 39 for similar subject matter used with other than video information.

By modifying synchronizing signal:
This subclass is indented under 210. Subject matter which modifies a synchronizing component of the video signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
206 for masking of video sync signal.

Including phase inversion of scan line information:
This subclass is indented under 221. Subject matter which inverts the phase of selected video scan line information signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
235 for phase inversion of scan line information in general.

Key signal on separate carrier:
This subclass is indented under 221. Subject matter wherein the signal needed to restore the modified synchronizing component is transmitted on a carrier distinct from the video carrier.

SEE OR SEARCH THIS CLASS, SUBCLASS:
239 for encrypted code signal of a video signal and subclass 240 for addressed code control of a video signal.

Including pseudo-synchronizing pulse:
This subclass is indented under 221. Subject matter wherein the modification includes the addition of a false synchronizing pulse.

SEE OR SEARCH THIS CLASS, SUBCLASS:
204 for video copy protection with modified sync signal.

Self-synchronizing circuit at receiver:
This subclass is indented under 221. Subject matter wherein the synchronizing component is regenerated by a circuit detecting a nonstandard timing characteristic of the modified video signal.
(1) Note. The circuit does not rely on a key signal for timing.

Key signal in blanking interval:
This subclass is indented under 221. Subject matter wherein the signal needed to restore the modified synchronizing component is transmitted during a video retrace portion.

SEE OR SEARCH THIS CLASS, SUBCLASS:
239 for encrypted code signal of a video signal and subclass 240 for addressed code control of a video signal.

Record or coin controlled:
This subclass is indented under 210. Subject matter wherein a video signal is made intelligible through the use of an object bearing a code or providing a medium of exchange.
(1) Note. Such objects may include coins and other currency, or credit and debit cards.

SEE OR SEARCH CLASS:
194, Check-Actuated Control Mechanisms, appropriate subclasses for coin operated equipment of general utility.
235, Registers, subclasses 375-386 for coded record operated equipment, absent cryptographic equipment.
348, Television, subclass 3 for remote computing a television subscriber payment and subclass 5.5 for television access control equipment without cryptographic structure.
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclasses 65-69 for a cryptographic secure transaction using an intelligent token.
713, Electrical Computers and Digital Processing Systems: Support, subclasses 172-174 for cryptographic multiple computer communication authentication using intelligent token.

Including key on record:
This subclass is indented under 227. Subject matter wherein a portable carrier provides a signal f or encryption or decryption.

Including authentication:
This subclass is indented under 227. Subject matter wherein the processing validates a portable carrier or the receiver.

SEE OR SEARCH THIS CLASS, SUBCLASS:
232 for video signal modification which has usage or charge determination ncluding authentication, subclasses 247 - 250 for cellular phone cryptographic authentication, and subclass 258 for a communication system which is position dependent or has authentication.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclass 67 for secure transaction cryptographic processing (e.g., EFT / POS) including authentication.
713, Electrical Computers and Digital Processing Systems: Support, subclasses 155-159 for multiple computer communication using cryptography having central trusted authority providing computer authentication, subclass 161 for multiple computer communication using cryptography where packet header denotes cryptographically protected data and having data authentication, and subclasses 168 - 181 for multiple computer communication using cryptography having particular communication authentication technique, particularly subclasses 172 - 174 for a multiple computer communication system using cryptography with authentication using an intelligent token.

Including usage recording:
This subclass is indented under 227. Subject matter wherein data representing program descrambling activity is written to a storage device.

SEE OR SEARCH THIS CLASS, SUBCLASS:
231 through 234 for video usage determination.

Usage or charge determination:
This subclass is indented under 210. Subject matter including determining the amount of use or a cost associated therewith in making the modified video signal intelligible.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclasses 52-54 for usage protection of distributed data files including
usage or charge determination, subclasses 77 - 79for a cryptographic electric commerce system including billing and subclasses 1 - 45 for automated electrical financial or business practice or management arrangement.

Including authentication:
This subclass is indented under 231. Subject matter wherein the usage or charge determination includes validation.

SEE OR SEARCH THIS CLASS, SUBCLASS:
229 for video signal modification which is record or coin controlled and includes authentication, subclasses 247 - 250 for cellular phone cryptographic authentication, and subclass 258 for a communication system which is position dependent or has authentication.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclass 67 for secure transaction cryptographic processing (e.g., EFT / POS) including authentication.
713, Electrical Computers and Digital Processing Systems: Support, subclasses 155-159 for multiple computer communication using cryptography having central trusted authority providing computer authentication, subclass 161 for multiple computer communication using cryptography where packet header denotes cryptographically protected data and having data authentication, and subclasses 168 - 181 for multiple computer communication using cryptography having particular communication authentication technique.

Including usage or charge recording at subscriber station:
This subclass is indented under 231. Subject matter wherein data representing program descrambling activity or cost thereof is written to a storage device at a user s location.

Including display of supplemental information:
This subclass is indented under 231. Subject matter wherein cost or auxiliary program data is presented to a user.

Phase inversion of scan line information:
This subclass is indented under 210. Subject matter which inverts the phase of selected video scan line information signals.

SEE OR SEARCH THIS CLASS, SUBCLASS:
38 and 39 for encryption using phase inversion not limited to video communication.
78 for nonstandard video scan pattern.
219 for video carrier phase shift.
222 for sync signal modification with phase inversion.

Modifying accompanying audio signal:
This subclass is indented under 210. Subject matter wherein a parameter of an audio signal is varied so as to render the sound unintelligible in a conventional receiver.

SEE OR SEARCH THIS CLASS, SUBCLASS:
275 and 276 for communication speech scrambler detail.

Including digital audio:
This subclass is indented under 236. Subject matter wherein the modified audio is transmitted as a series of pulses.

SEE OR SEARCH CLASS:
700, Data Processing: Generic Control Systems and Specific Applications, subclass 94 for digital audio signal processing not elsewhere provided for.
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression,
appropriate subclasses for speech signal processing in general.

Including frequency modification of audio signal or frequency shifting of audio carrier:
This subclass is indented under 236. Subject matter wherein audio modification occurs by varying a frequency characteristic of an audio signal or by frequency shifting of an audio carrier.

Encrypted code control signal:
This subclass is indented under 210. Subject matter wherein a control coding signal modifying the video electric signal has itself been made unintelligible.

SEE OR SEARCH THIS CLASS, SUBCLASS:
277 through 47 for cryptographic key management.

Including addressed decoder control signal:
This subclass is indented under 210. Subject matter wherein a control coding signal includes a designation of a particular descrambling device.

Having program ID or authorization:
This subclass is indented under 240. Subject matter wherein the addressed decoder signal includes a unique identifier for a particular video signal or access thereto.

Having command signal for receiver:
This subclass is indented under 240. Subject matter wherein the addressed decoder signal provides for actuation
or modification of receiver operation.

FACSIMILE CRYPTOGRAPHY:
Subject matter including an optically scanned static picture represented by an electrical signal which has been made unintelligible.
(1) Note. Processing of a picture signal representing a time varying object or image is classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:
51 for generating a printed record of decrypted characters, rather than an image of a document.
200 and 242 for video cryptography of a time varying image.

SEE OR SEARCH CLASS:
348, Television, appropriate subclasses for television processing absent encryption.
358, Facsimile, appropriate subclasses for facsimile equipment absent signal encryption.

Synchronization:
This subclass is indented under 243. Subject matter including a signal for placing a transmitter and receiver into a particular in step relationship.

Nonstandard scan pattern:
This subclass is indented under 243. Subject matter wherein the normal ordering of the scan components is modified.
(1) Note. Examples of a nonstandard scan pattern are: nonadjacent scan lines, oppositely directed scan lines, or nonsequential video information in a standard scan line.
(2) Note. Scan components are: line segments, lines, fields, and frames.

SEE OR SEARCH THIS CLASS, SUBCLASS:
214 and 215 for nonstandard scan pattern of video information.
235 for phase inversion of scan line information.

Including generation of an associated coded record:
This subclass is indented under 243. Subject matter wherein a machine readable indicia is produced which is representative of the scanned static picture.

SEE OR SEARCH CLASS:
713, Electrical Computers and Digital Processing Systems: Support, subclass 179 for digital signature representation with generation of associated coded record.

CELLULAR TELEPHONE CRYPTOGRAPHIC AUTHENTICATION :
Subject matter wherein use of a cellular telephone system is restricted to an authorized subscriber by the use of an encryption method.

SEE OR SEARCH THIS CLASS, SUBCLASS:
229 for video signal modification which is record or coin controlled and includes authentication, subclass 232 for video signal modification which has usage or charge determination including authentication, subclass 258 for a communication system which is position dependent or has authentication, and subclasses 270 - 274 for cryptography in a wireless communication system.

SEE OR SEARCH CLASS:
370, Multiplex Communications, subclasses 352-356 for internet telephony.

Visiting center:
This subclass is indented under 247. Subject matter wherein authorization to a cellular system other than the subscriber s home system is processed through an
intermediary.

SEE OR SEARCH CLASS:
455, Telecommunications, subclass 433 for cellular roaming processing in general which includes visitor location registration detail.

Initialization:
This subclass is indented under 247. Subject matter wherein cryptographic information necessary for authentication is preloaded.

Usage pattern detection:
This subclass is indented under 247. Subject matter wherein authorization is permitted by comparing current usage with previous usage.

ELECTRONIC GAME USING CRYPTOGRAPHY:
Subject matter including an electronic amusement device having a signal therein protected by cryptographic structure or methods.

SEE OR SEARCH CLASS:
463, Amusement Devices: Games, subclasses 1-47 for computer games in general.

ELECTRIC SIGNAL MASKING:
Subject matter wherein the characteristics of an information bearing electric signal are obscured by the addition of an extraneous interfering signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
205 and 206 - 209 for video electric signal masking.
210 and 211 242 for video signal encryption by scrambling.
287 through 53 for signal encryption in general by scrambling or other modification.

SEE OR SEARCH CLASS:
455, Telecommunications, subclass 1 for jamming of a modulated carrier wave signal.

By signal having discrete frequency component:
This subclass is indented under 252. Subject matter wherein the masking signal is formed from a finite number of individual frequency components.

By signal having discrete step amplitude variation:
This subclass is indented under 252. Subject matter wherein the amplitude of the masking signal varies in discrete steps.

COMMUNICATION SYSTEM USING CRYPTOGRAPHY:
Subject matter including cryptographic structure or methods which protect the transmission or reception of information.
(1) Note. Key distribution is excluded herein and classified elsewhere with key management.

SEE OR SEARCH THIS CLASS, SUBCLASS:
277 through 47 for key management and particularly subclasses 278 - 285 for key distribution.

SEE OR SEARCH CLASS:
340, Communications, Electrical, appropriate subclasses for electrical communication in general.
370, Multiplex communications, appropriate subclasses for multiplex communication in general.
375, Pulse or Digital Communications, appropriate subclasses for generic digital communication.
379, Telephonic Communications, appropriate subclasses for wired telephone systems in general.
455, Telecommunications, appropriate subclasses for telecommunication including a modulated carrier.

Fiber optic network:
This subclass is indented under 255. Subject matter including plural nodes joined by an optical waveguide for the transmission or reception of light waves.

SEE OR SEARCH CLASS:
359, Optics: Systems (Including Communication) and Elements, subclasses 109-195 for optical communication systems that may include an optical waveguide absent encryption.

Circuit switched network (e.g., wired telephone):
This subclass is indented under 255. Subject matter wherein protection of the transmission or reception of information occurs in a system having plural nodes joined by switched physical links (usually two-way voice).
(1) Note. Excluded herein is symmetric key cryptography which includes a modem. This is classified elsewhere.

SEE OR SEARCH THIS CLASS, SUBCLASS:
266 for symmetric key cryptography which includes a modem.
275 through 276 for speech scrambling detail per se.

SEE OR SEARCH CLASS:
379, Telephonic Communications, appropriate subclasses for wired telephone circuits in general.

Position dependent or authenticating:
This subclass is indented under 255. Subject matter
wherein cryptographic protection is based upon or validates the spatial location of a transmitter or receiver.

SEE OR SEARCH THIS CLASS, SUBCLASS:
229 for video signal modification which is record or coin controlled and includes authentication, subclass 232 for video signal modification which has usage or charge determination including authentication, and subclasses 247 - 250 for cellular phone cryptographic authentication.

SEE OR SEARCH CLASS:
342, Communications: Directive Radio Wave Systems and Devices (E.G., Radar, Radio Navigation), 357.01 for directive radio wave systems including a satellite with position indicating.
701, Data Processing: Vehicles, Navigation, and Relative Location, subclasses 207-223 for navigation employing position determining equipment.
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclass 67 for secure transaction cryptographic processing (e.g., EFT / POS) including authentication.
713, Electrical Computers and Digital Processing Systems: Support, subclasses 155-159 for multiple computer communication using cryptography having central trusted authority providing computer authentication, subclass 161 for multiple computer communication using cryptography where packet header denotes cryptographically protected data and having data authentication, and subclasses 168 - 181 for multiple computer communication using cryptography having particular communication authentication technique.

Symmetric key cryptography:
This subclass is indented under 255. Subject matter wherein the encryption and decryption keys are the same.

SEE OR SEARCH THIS CLASS, SUBCLASS:
29 for a generic NBS/DES algorithm.
42 for generic data stream/substitution enciphering.
277 through 47 for cryptographic key management.

Symmetric key synchronization:
This subclass is indented under 259. Subject matter including transmission of a signal for generating identical transmitting and receiving keys in step relationship.

Including frame synchronization:
This subclass is indented under 260. Subject matter wherein the synchronizing signal is determined by the starting point of a discrete data block input to a receiver.

SEE OR SEARCH THIS CLASS, SUBCLASS:
212 for plural video stream multiplexing.
274 for wireless communication with synchronization in general.

Transmitting a seed, sequence, or initial value:
This subclass is indented under 260. Subject matter wherein the synchronizing signal is a value indicating a starting point for key generation

Nonlinear or chaotic system:
This subclass is indented under 260. Subject matter wherein the key synchronization is used in a nondeterministic process.

Key derived from addressable memory element:
This subclass is indented under 259. Subject matter wherein the key is extracted from a static storage device having a specified location designation.

Combining outputs of shift register:
This subclass is indented under 259. Subject matter wherein the encryption or decryption includes summing the taps from individual stages of a shift register.

SEE OR SEARCH CLASS:
365, Static Information Storage and Retrieval, subclasses 80-90 for a magnetic shift register.
377, Electrical Pulse Counters, Pulse Dividers or Shift Registers, subclasses 64-81 for a shift register in general.

Including a modem:
This subclass is indented under 259. Subject matter including a device converting a digital signal to a signal suitable for telephone network transfer.

SEE OR SEARCH THIS CLASS, SUBCLASS:
257 through 41 for a cryptographically protected circuit switched network.

Correcting for random appearance of control character code:
This subclass is indented under 255. Subject matter wherein an undesired sequence representing a command signal within a body of data is compensated.

SEE OR SEARCH THIS CLASS, SUBCLASS:
51 for electric signal modification with printed copy production.

Pseudo-random sequence scrambling:
This subclass is indented under 255. Subject matter wherein modification of a digital data signal is
affected to randomly distribute consecutive appearance of ones and zeros.

Having compression:
This subclass is indented under 255. Subject matter wherein the quantity of data representing a signal to be communicated is reduced.

SEE OR SEARCH THIS CLASS, SUBCLASS:
217 for video cryptography having compression.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclass 60 for digital to digital conversion to or from packed format.
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression, subclass 503 and 504 for audio signal time compression or expansion.
708, Electrical Computers: Arithmetic Processing and Calculating, subclass 203 for compression/decompression by digital computer.

Wireless communication:
This subclass is indented under 255. Subject matter including cryptographic structure or methods which protect the transmission or reception of information over a nonphysical link by electromagnetic waves.

SEE OR SEARCH CLASS:
359, Optics: Systems(Including Communication) and Elements, subclasses 109-195 for optical communication.
370, Multiplex Communications, appropriate subclasses for multiplex communication system in general.
375, Pulse or Digital Communications, appropriate subclasses for wireless digital communication.
455, Telecommunications, appropriate subclasses for wireless telecommunication systems.

Having receiver selection (e.g., pager):
This subclass is indented under 270. Subject matter wherein communication is established between a transmitter and one of plural receivers.

SEE OR SEARCH CLASS:
340, Communications: Electrical, subclasses 825.44-825.48 for selective code responsive device with indicator or alarm.
455, Telecommunications, subclass 31.1 38.5 for system with receiver selection.

Including hand-off based cryptographic alteration:
This subclass is indented under 270. Subject matter wherein cryptographic protection is extended or modified by a switch between serving base stations of a mobile receiver.

SEE OR SEARCH THIS CLASS, SUBCLASS:
247 and 248 - 250 for cellular phone cryptographic authentication.

SEE OR SEARCH CLASS:
370, Multiplex Communications, subclass 331 for multiplex communication system handoff.
455, Telecommunications, subclasses 436-444 for cellular handoff.

Rekeying system:
This subclass is indented under 270. Subject matter wherein a key previously used for communication is replaced.

Synchronization:
This subclass is indented under 270. Subject matter including a signal for placing the transmitter and receiver into a particular in step relationship.

Speech scrambler detail:
This subclass is indented under 255. Subject matter wherein a signal representative of speech is made unintelligible.
(1) Note. The signal may either be analog or digital.

SEE OR SEARCH THIS CLASS, SUBCLASS:
236 237, and 238 for video cryptography having modified audio signal.
257 through 41 for a cryptographically protected circuit switched network.

SEE OR SEARCH CLASS:
704, Data Processing: Speech Signal Processing, Linguistics, Language Translation, and Audio Compression/Decompression, subclasses 200-278 for speech signal processing in general.

Including sampling:
This subclass is indented under 275. Subject matter wherein a sequence of signal representations are obtained at discrete time intervals.

SEE OR SEARCH CLASS:
341, Coded Data Generation or Conversion, subclasses 122-125 for sample and hold circuits.
700, Data Processing: Generic Control Systems and Specific Applications, subclass 94 for digital audio signal processing not elsewhere provided for.

KEY MANAGEMENT:
Subject matter providing supervision or control of a signal necessary for encryption or decryption.

SEE OR SEARCH THIS CLASS, SUBCLASS:
259 through 266 for a communication system using symmetric key cryptography.

SEE OR SEARCH CLASS:
705, Data Processing: Financial, Business Practice, Management, or Cost/Price Determination, subclass 71 for secure transactions including key management.
713, Electrical Computers and Digital Processing Systems: Support, subclass 171 for multiple computer communication authentication having key exchange.

Key distribution:
This subclass is indented under 277. Subject matter wherein the manner of sending or receiving the cryptographic key is detailed.

Key distribution center:
This subclass is indented under 278. Subject matter wherein distribution of a key is from a single source to plural distributed stations.

Control vector or tag:
This subclass is indented under 279. Subject matter wherein a key has associated data that limits key use.

Using master key (e.g., key-encrypting-key)
This subclass is indented under 279. Subject matter wherein a distributed short term key is protected by a separate private long term key.

By public key method:
This subclass is indented under 279. Subject matter wherein a distributed key is protected by a public key algorithm.

User-to-user key distributed over data link (i.e., no center):
This subclass is indented under 278. Subject matter wherein a key is directly distributed between users over the same channel as the data.

Using master key (e.g., key-encrypting-key):
This subclass is indented under 283. Subject matter wherein a distributed short term key is protected by a separate private long term key.

By public key method:
This subclass is indented under 283. Subject matter wherein a distributed key is protected by a public key algorithm.

Key escrow or recovery:
This subclass is indented under 277. Subject matter wherein the key is deposited or retrieved to or from a third party.

ELECTRIC SIGNAL MODIFICATION:
Subject matter which makes an information signal unintelligible by varying a parameter of the signal.

SEE OR SEARCH THIS CLASS, SUBCLASS:
210 and 211 - 242 for video electric signal modification.
252 253, and 254 for information signal encryption by masking with a second signal.
255 and 256 276 for a cryptographically protected communication system.

Parenthetical references in the titles below refer to the U.S. classifications from which these art collections are derived.

STORED INFORMATION ACCESS OR COPY PREVENTION (380/3): Foreign art collection under the class definition which conceals or prevents rerecording of machine readable information by making the stored information unintelligible.

Digital data (e.g., software program protection, data encryption) (380/4): Foreign art collection under collection 103 which prevents duplication of, or unauthorized access to, information stored as a group of discrete pulses.

Video (380/5): Foreign art collection under collection 103 for preventing rerecording of, or unauthorized access to, a stored picture signal representative of an object or image.

ELECTRIC SIGNAL MASKING (380/6): Foreign art collection under the class definition wherein the characteristics of an information bearing electric signal are obscured by the addition of an extraneous interfering signal.

Video (380/7): Foreign art collection under collection 106 for masking a picture signal representative of an object or image.

By signal having discrete step amplitude variation (380/8): Foreign art collection under collection 106 wherein the amplitude of the masking signal varies in discrete steps.

ELECTRIC SIGNAL MODIFICATION (E.G., SCRAMBLING) (380/9): Foreign art collection under the class definition which makes an information signal unintelligible by varying a parameter of the information signal.

Video (380/10): Foreign art collection under collection 109 for modifying either (a) a picture signal representative of an object or image, or (b) a signal transmitted with such a picture signal (e.g., audio).

Variable time delay modulation of baseband video signal (380/11): Foreign art collection under collection 110 which encrypts a picture signal before carrier modulation by application of varying amounts of time delay.

Carrier phase shift (380/12): Foreign art collection under collection 110 in which a picture signal modulated onto a carrier wave is modified by a phase change of the carrier.

Carrier frequency conversion (380/13): Foreign art
collection under collection 110 in which the frequency of a carrier wave is modified for encryption.

Nonstandard scan of video information (380/14): Foreign art collection under collection 110 which encrypts the video signal by use of nonstandard scan components.

By modifying synchronizing signal (380/15): Foreign art collection under collection 110 which encrypts the synchronizing portion of the video signal.

Record or coin controlled (380/16): Foreign art collection under collection 110 wherein video signal modification is actuated by an object authorizing or making payment for use of the equipment.

Phase inversion of scan line information (380/17): Foreign art collection under collection 110 which inverts the phase of selected video scan line information signals.

Facsimile (380/18): Foreign art collection under collection 110 which transmits or reproduces an optically scanned static picture represented by an electrical signal.

Encrypting of accompanying audio signal (380/19): Foreign art collection under collection 110 which modifies an audio signal so as to render the sound unintelligible in a conventional receiver.

Control coding (380/20): Foreign art collection under collection 110 which transmits an auxiliary signal between the transmitter and receiver for actuation or modification of an encrypting or decrypting function.

Having transmission or distribution of key signal (380/21): Foreign art collection under collection 109 wherein a sequence of signals necessary for decoding of an encrypted signal is transmitted over a data link.

With particular synchronization or initiation (380/48): Foreign art collection under collection 109 which uses a particular signal or circuit for control of timing relationships between a transmitting encrypting device and a receiving decrypting device.

With digital signal handling (e.g., digital control, digital computer communication) (380/49): Foreign art collection under collection 109 in which an encrypting or decrypting device utilizes a digital signal manipulation technique on the information signal.

Including shift register or memory (380/50): Foreign art collection under collection 149 which uses digital information storage equipment for encryption or decryption of the information signal.