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7613296 |
M6 block cipher system and method for encoding content and authenticating a device
An M 6 block cipher system and method for encoding content and authenticating a device may use an M 6 core. The M 6 block cipher system may include a rotate constant selector selecting one or...
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7599927 |
Method for searching content particularly for extracts common to two computer files
The present invention relates to searching content, particularly for at least one extract common to a first data file and a second data file. The method comprises a preliminary step of preparing at...
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7359512 |
Authentication in a quantum cryptographic system
A quantum cryptographic device provides authentication services over the optical (quantum) channel and the public channel. In one implementation, polarizers generate optical pulses that have a...
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7024018 |
Watermark position modulation
Methods and apparatus are provided for embedding information in a host signal based on the positioning of watermarks within the host signal. An embedder provides (i.e. embeds) a plurality of...
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7006555 |
Spectral audio encoding
Blocks of audio are encoded based upon corresponding first and second frequencies. The first and second frequencies are hopped from block to block. An audio quality measure (AQM) is computed for...
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7003118 |
High performance IPSEC hardware accelerator for packet classification
An architecture for a high performance IPSEC accelerator. The architecture includes components for scanning fields of packets, programming an IPSEC services device according to the scanned fields,...
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6996237 |
Apparatus and methods for including codes in audio signals
Apparatus and methods for including a code having at least one code frequency component in an audio signal are provided. The abilities of various frequency components in the audio signal to mask...
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6961431 |
Analog privacy scrambler and scrambling method
A system and method for maintaining privacy in transmission of a high bandwidth analog signal. A preferred system and method breaks an input signal into bands and then uses Walsh codes to overlay...
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6879703 |
Method and apparatus for watermarking images
Digital watermarks are embedded in image data ( 102 )in order to enable authentication of the image data and/or replacement of rejected portions of the image data. Authentication codes are derived...
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6862355 |
Message reconstruction from partial detection
A method and system for reliably detecting encoded messages included in audio media data in varying acoustic environments, where only a portion of the predetermined message may have been received...
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6430291 |
Method and device for controlling information signal recording
An anti-duplication control signal detection section detects an anti-duplication control signal added on a video signal S1 and supplies it to a system controller as a duplication prevention control...
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6151578 |
System for broadcast of data in an audio signal by substitution of imperceptible audio band with data
A system for broadcasting data (D) that can transmit information in the passband of a broadcast audio-frequency signal (S). The system can determine at least one frequency band (F' 13 , . . . , F'...
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6035177 |
Simultaneous transmission of ancillary and audio signals by means of perceptual coding
A communication system for simultaneously transmitting ancillary codes and audio signals via a conventional audio communications channel using perceptual coding techniques is disclosed. An encoder...
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5940135 |
Apparatus and method for encoding and decoding information in analog signals
Apparatus and methods are provided for encoding, storing and decoding auxiliary information on an analog source signal in a way which has minimal impact on the human perception of the source...
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5493612 |
Secure communication keying system
The secure communication keying system has a noise generator whose output a predetermined finite band of noise within, for example, the zero to eleven hundred cycle per second range. The noise...
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5319735 |
Embedded signalling
A code signal representing a sequence of code symbols carrying digital information is generated with the frequency components of the code signal being essentially confined to a preselected...
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5181243 |
System and method for communications security protection
A system and method are disclosed for preventing intelligible interception of information signals transmitted over a two-direction line. A masking signal is applied through a hybrid circuit at the...
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5177785 |
Method and system for secure telecommunications
There is disclosed a method and system for injecting a number of different signal patterns onto a tone encoded telecommunications line for the purpose of preventing unauthorized eavesdropping. The...
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5168519 |
System and method for securing DTMF transmission
A technique for inhibiting intelligible interception of information signals transmitted over a line from a first site to a second site. A masking signal is applied to the line immediately upon the...
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5113437 |
Signal identification system
A signal identification system, suitable for producing an identification code on a sound track recording is described. The system includes an encoder 209 effective to eliminate a variable sequence...
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5036542 |
Audio surveillance discouragement apparatus and method
An audio surveillance discouragement apparatus or system comprising, at least, first generating device, second generating device, first speaker and second speaker. The first speaker is coupled to...
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4754481 |
Expanded partial response processing for analog signal enciphering and the like
Partial response signal processing is applied to samples of an analog signal quantized in an amplitude range having a sufficient number of levels that a sample amplitude error of a small percentage...
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4674124 |
Multichannel masking sound generator
In the masking sound source disclosed herein, easily adjustable but matching acoustic energy spectrums are obtained from different channels by providing, for each channel, a plurality of bandpass...
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4438526 |
Automatic volume and frequency controlled sound masking system
A sound masking system for generating background sound. The background sound is automatically adjusted to ambient noise levels by adjusting the amplitude of the frequency levels detected.
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4160875 |
Security system
A security system for use in homes, hotels, businesses, schools, streets, and other locations requiring a high degree of security but where it is important to insure the privacy of the protected...
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4133977 |
Voice scrambler using syllabic masking
Voice signals are combined with a masking signal that changes frequencies between discrete frequencies at a selected rate and in a random manner. The combined voice spectrum and masking signal is...
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3985958 |
Secret telephony
1. In secret telephony, means to analyze speech message waves into slowly varying currents representative of energy variations in respective portions of the speech frequency band, distributor means...
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3978288 |
Method and apparatus for the secret transmission of speech signals
Method and apparatus for enhancing the secret (confidential) transmission of voice (speech) type signals. The voice signals are encoded at a transmitter facility. Filling signals are inserted into...
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3897591 |
Secret transmission of intelligence
1. In a signal privacy system, means to convert a gradually varying signal current wave into a stepped wave, means to superpose on said stepped wave a masking current varying in magnitude in a...
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3887772 |
Signal privacy with safety feature
1. In a signal privacy system, a signal current input circuit, a privacy equipment including a source for supplying masking currents thereto, means for combining said masking currents with said...
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3845391 |
COMMUNICATION INCLUDING SUBMERGED IDENTIFICATION SIGNAL
A technique for identifying a program with an identification code in which the code is modulated onto an audio frequency subcarrier and transmitted with the program. A short time period, narrow...
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3651268 |
COMMUNICATION PRIVACY SYSTEM
A communication system which employs masking signals to encode the transmitted signal and means to strip the masking signals at the receiving end. Provision is made for simple, replaceable, plug-in...
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3478169 |
SECRET SCA COMMUNICATION SYSTEMS AND APPARATUS
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3470468 |
SYNTHESIS AND WAVE GENERATION WITH COMPACTLY CARRIED WAVEFORMS
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3381223 |
Transmission system for use in a subscription radio communcation system
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3213199 |
System for masking information
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3077518 |
Apparatus for camouflaging communication signals
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