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Audio Watermarking and Steganography

Nov 11, 2014



Some Audio Steganography and Watermarking algorithms

  • 1. AUDIO WATERMARKING AND STEGANOGRAPHY Anirudh Shekhawat Manan Shah Prateek Srivastava Pratik Poddar Guided by: Prof. Bernard Menezes
  • 2. DIGITAL WATERMARKING Embedding perceptually transparent data in digital media Watermark can be detected and retrieved by a computer algorithm Applications include broadcast monitoring, fingerprinting, copyright protection and steganography
  • 3. STEGANOGRAPHY Steganography literally means "secret writing Hiding data in a digital media Avoids the suspicion and scrutiny an encrypted message would arouse Applications include "covert communication Examples from history - Invisible ink, Scalp tattoo, Pinholes
  • 5. COPYRIGHT PROTECTION Ownership information can be embedded in the media Presence of the watermark can be demonstrated to prove ownership The watermark must survive compression
  • 6. FINGERPRINTING Embedding a serial number in each copy of a media before distribution Can be used to trace down the originator of a particular illegal copy of media The watermark must be secure against attacks
  • 7. BROADCAST MONITORING Programs and advertisements broadcasted can be monitored by an automated system Illegal broadcasts can be identified by monitoring satellite nodes High Bit rate and low complexity are required
  • 8. COVERT COMMUNICATION Embedding data such that existence of a watermark cannot be detected Aimed at protecting the sender and receiver rather than the message Terrorists have been reported to hide messages in images to communicate
  • 10. PERCEPTUAL TRANSPARENCY Primary requirement in watermarking Watermark should be imperceptible to human auditory system Watermarking is more difficult for audio as compared to images
  • 11. WATERMARK BIT RATE Represented in bits per second (bps) Required rates vary across applications (0.5 bps in copyright protection and 15 bps in broadcast monitoring) Attainable values depend upon level of compression of audio
  • 12. ROBUSTNESS The ability of the watermark to survive common signal processing manipulations Required against a predefined set of manipulations Required in some applications (radio broadcast monitoring) but not at all required in some (tampering detection)
  • 13. BLIND AND INFORMED DETECTION Informed: with access to original(host) audio Blind: without access to original audio Informed techniques are more secure Examples Blind: Tampering detection, Information Carrier Informed: Steganography
  • 14. SECURITY Adversary must not be able to detect the existence of embedded data Not be able to extract or modify the data without the secret key In some cases the watermark is encrypted before being embedded
  • 16. 1) LEAST SIGNIFICANT BIT ENCODING Watermark added in the least significant bit of amplitude Easy to embed and retrieve High bit rate Low robustness
  • 17. WATERMARKING, COMPRESSION & REDUNDANCY Lossy compression destroys watermark. To make watermark robust against compression, we need sufficient redundancy LSB encoding: Robustness vs Imperceptibility? LSB Watermarking in JPEG done Possible for MP3?
  • 18. 2) PHASE MODULATION Embed watermark by modulating phase in host audio Robust against signal processing manipulations Extraction or detection of watermark needs original audio Suitable for applications where security and robustness are important, e.g. copyright protection
  • 19. 3) FREQUENCY DOMAIN STEGANOGRAPHY Shanon Sampling theorem Sampling rate for CD is 44.1KHz the highest frequency is 18KHz Average peak frequency which a human can hear is 18Khz 22 18 = 4KHz band goes unused
  • 20. UNDERLYING PRINCIPLE Use the 18Khz - 22KHz frequency band to hide the message Message signal Base signal Fig : Combined Signal
  • 21. MERITS AND DEMERITS Merits Longer message can be hidden in a given base Less likely to be affected by errors during transmission Demerits Message signal has limited frequency range Low recovery quality
  • 22. 4) ECHO HIDING Embeds data by introducing echo in the original signal. Resilient to lossy data compression algorithms.
  • 23. ECHO ENCODING AND DECODING Encoding Decoding
  • 25. REFERENCES Juergen Seitz, Digital Watermarking for Digital Media, ISBN 159140519X, 2005, Information Resources Press, Arlington, VA, USA Nedeljko Cvejic, Algorithms for audio watermarking and steganography, ISBN 9514273834, 2004, Oulu University Press, Oulu C.H. Yeh & C.J Kuo, Digital watermarking through quasi m-arrays, Proceedings of the IEEE Workshop on Signal Processing Systems 1999, 456-461 Guy Belloch, Introduction to Data Compression, Draft version, Algorithms in the real world Kuo S, Johnston J, Turin W & Quackenbush S Covert audio- watermarking using perceptually tuned signal independent multiband phase modulation, IEEE International Conference on Acoustics, Speech, and Signal Processing 2002, 1753-1756
  • 26. REFERENCES Foo, S.W., Yeo, T.H., & Huang, D.Y. (2001). An adaptive audio watermarking system. Proceedings of the IEEE Region 10 International Conference on Electrical and Electronic Technology, 509513. Huang, D.Y., & Yeo, Y.H. (2002). Robust and inaudible multi-echo audio watermarking. Proceedings of the IEEE Pacific-Rim Conference on Multimedia, 615622. Bender, W., Gruhl D. Echo Hiding, International Workshop on Information Hiding, 1996.