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Class Information
Number: 380/253
Name: Cryptography > Electric signal masking > By signal having discrete frequency component
Description: Subject matter wherein the masking signal is formed from a finite number of individual frequency components.

Patents under this class:

Patent Number Title Of Patent Date Issued
8676364 Apparatus and method for synchronizing multichannel extension data with an audio signal and for processing the audio signal Mar. 18, 2014
8670986 Method and apparatus for masking speech in a private environment Mar. 11, 2014
8634946 Apparatus and method for calculating a fingerprint of an audio signal, apparatus and method for synchronizing and apparatus and method for characterizing a test audio signal Jan. 21, 2014
8600055 Method and system using stealth noise modulation Dec. 3, 2013
8594575 Shifted channel characteristics for mitigating co-channel interference Nov. 26, 2013
8571213 Security method for preventing the unauthorized use of multimedia contents Oct. 29, 2013
8559865 Method and apparatus for providing jammer detection in a receiver Oct. 15, 2013
8522032 System and method to prevent audio watermark detection Aug. 27, 2013
8369972 Methods and apparatus to perform audio watermarking and watermark detection and extraction Feb. 5, 2013
8331562 Image forming apparatus, image forming method and, computer readable medium and computer signal Dec. 11, 2012
8280051 Secure presentation of media streams in response to encrypted content Oct. 2, 2012
8074081 Method for replacing contents of a data storage unit Dec. 6, 2011
7961881 Apparatus and methods for including codes in audio signals Jun. 14, 2011
7809143 QKD system with synchronization channel verification Oct. 5, 2010
7796758 Method and apparatus for securing transmission on a speakerphone or teleconference call Sep. 14, 2010
7613296 M6 block cipher system and method for encoding content and authenticating a device Nov. 3, 2009
7599927 Method for searching content particularly for extracts common to two computer files Oct. 6, 2009
7359512 Authentication in a quantum cryptographic system Apr. 15, 2008
7024018 Watermark position modulation Apr. 4, 2006
7006555 Spectral audio encoding Feb. 28, 2006
7003118 High performance IPSEC hardware accelerator for packet classification Feb. 21, 2006
6996237 Apparatus and methods for including codes in audio signals Feb. 7, 2006
6961431 Analog privacy scrambler and scrambling method Nov. 1, 2005
6879703 Method and apparatus for watermarking images Apr. 12, 2005
6862355 Message reconstruction from partial detection Mar. 1, 2005
6430291 Method and device for controlling information signal recording Aug. 6, 2002
6421445 Apparatus and methods for including codes in audio signals Jul. 16, 2002
6330335 Audio steganography Dec. 11, 2001
6175627 Apparatus and method for embedding and extracting information in analog signals using distributed signal features Jan. 16, 2001
6151578 System for broadcast of data in an audio signal by substitution of imperceptible audio band with data Nov. 21, 2000
6035177 Simultaneous transmission of ancillary and audio signals by means of perceptual coding Mar. 7, 2000
5940135 Apparatus and method for encoding and decoding information in analog signals Aug. 17, 1999
5764763 Apparatus and methods for including codes in audio signals and decoding Jun. 9, 1998
5493612 Secure communication keying system Feb. 20, 1996
5450490 Apparatus and methods for including codes in audio signals and decoding Sep. 12, 1995
5319735 Embedded signalling Jun. 7, 1994
5181243 System and method for communications security protection Jan. 19, 1993
5177785 Method and system for secure telecommunications Jan. 5, 1993
5168519 System and method for securing DTMF transmission Dec. 1, 1992
5148478 System and method for communications security protection Sep. 15, 1992
5113437 Signal identification system May. 12, 1992
5036542 Audio surveillance discouragement apparatus and method Jul. 30, 1991
4972469 System and method for communications security protection Nov. 20, 1990
4754481 Expanded partial response processing for analog signal enciphering and the like Jun. 28, 1988
4674124 Multichannel masking sound generator Jun. 16, 1987
4438526 Automatic volume and frequency controlled sound masking system Mar. 20, 1984
4160875 Security system Jul. 10, 1979
4133977 Voice scrambler using syllabic masking Jan. 9, 1979
3985958 Secret telephony Oct. 12, 1976
3978288 Method and apparatus for the secret transmission of speech signals Aug. 31, 1976

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