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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 |
| 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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