Transformed-key asymmetric watermarking system

H. Choi, K. Lee, T. Kim

Research output: Contribution to journalConference articlepeer-review

8 Scopus citations


This paper proposes a new asymmetric watermarking system. Digital watermarking is a method to imperceptibly embed certain information in digital multimedia data. Watermarking systems are classified as symmetric and asymmetric ones. The former uses the same key for encoding and decoding and is suitable for private applications in the sense that the key has to be maintained private among the authorized embedder and detectors. The latter, which uses different keys for encoding and decoding, is for public applications. In the proposed asymmetric system, a linear transformation A is applied to the primitive key u to form the private encoding key Au and the public decoding key A-tu, where -t denotes inverse transpose. The transformation mostly cancels out when the decoding key is correlated to watermarked signal containing the encoding key, which is possibly contaminated with noise. Our analysis shows that this simple scheme provides not only reliability in watermark detection but also security from any attempts to identify or erase the encoding key. We also address the issue of selecting a good transformation matrix.

Original languageEnglish
Pages (from-to)280-289
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2001
EventSecurity and Watermarking of Multimedia Contents III - San Jose, CA, United States
Duration: 22 Jan 200125 Jan 2001


  • Asymmetric key
  • Digital watermarking
  • Linear transformation
  • Public detection


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