Cryptography – By modifying optical image
Reexamination Certificate
1998-04-27
2002-03-19
Peeso, Thomas R. (Department: 2132)
Cryptography
By modifying optical image
C382S232000
Reexamination Certificate
active
06359985
ABSTRACT:
TECHNICAL FIELD
The invention is in the field of marking binary coded data sets, particularly concerning image data and audio signals by embedding at least one information unit in a data set.
BACKGROUND ART
Protection of intellectual property rights and usage rights is one of the main concerns of producers of information, publishers, media companies and usage rights brokers. One of the paramount concerns of the creators of intellectual property is protection from illicit copying and distribution of copyrighted multimedia data. In many cases, as for instance in the case of the distribution of digitally stored data the direct inhibition of illicit distribution is not possible. To counter this, techniques have been developed which allow the detection and tracking of illicit copying and distribution as well as tracing the original perpetrator.
Such measures for embedding information in the particular electronic data sets constitute so-called steganographic measures which allow the integration of additional secret information in data by modifying the original data without significantly degrading the quality or appearance of the original data.
A number of different methods for slightly modifying original digital data in order to embed additional information have been investigated. Matsui & Tanaka have proposed a number of steganographic methods for identifying intellectual property in digital images, videos and facsimiles. Refer to the publication of Matsui and K. Tanaka “Video-Steganography: How to secretly embed a signature in a picture”, IMA Intellectual Property Proceedings Vol. 1, No. 1, 1994 for details.
The underlying principle of their methods is based on embedding the information in such a way as to make it appear that it is merely a further imprecision (i.e. an increase in the noise level) in the original data.
Researchers at AT&T have investigated possibilities for embedding information in another class of documents, namely structured text, by means of inserting distortions in the form of varying in a controlled fashion the spacing between subsequent lines as well as the inter-word spacing. Refer to the publication by J. Brassil et al. “Electronic Marking and Identification Techniques to Discourage Document Copying”, AT&T Bell Laboratories, Murray Hill, N.J., 1994 for details.
The existing steganographic techniques for digital imagery do not by any measure meet the requirements for the protection and proof of intellectual property rights to multimedia productions and information. This is due to the fact that the techniques do not offer any protection against both intentional and inadvertent attacks which are possible by digital processing especially of image data. The deletion, modification or gross distortion of the embedded information may easily be accomplished by a lossy image compression, low pass filtering and/or change of the data/image representation in the case of the older techniques. However, such processing steps are often performed by necessity on the way of a digital multimedia document from the creator to the final consumer or user; hence the mentioned techniques are unsuited for yielding a proof of authenticity or for identification of the intellectual rights holder.
The European publication EP 0 581 317 contains a method for digital marking of digital data sets, e.g. digital image data. The method described in this publication allows the integration of digital signatures, a.k.a. markings in digital image data. The digital signatures are embedded to allow the future identification of the images. This is accomplished by identifying pixels of the image which contain relative minima and maxima (i.e. extreme values) in the pixel values. From the thusly identified pixels, pixels are determined for the integration of an identification code, the so-called signature. In order to integrate each bit of the signature at a selected point of the image, the pixel values of the selected pixel as well as the pixel values of the surrounding pixels are adapted, i.e. modified. This technique has the Immanent drawback that the selected positions for the integration of the signature values are easily determined and may therefore be assumed as known to attackers. By selecting the positions of the originally present extreme values the thus integrated identification codes may easily be detected and removed accordingly.
Similarly, the European Publication EP 0 614 308 A1 contains a method for encrypting data. Such encryption techniques accomplish the complete scrambling of the entire data set for unauthorized access. In this technique, high resolution image components are protected from illicit access by means of a key or an encryption technique. Non-high-resolution image components may however remain freely accessible so that a hierarchical access control for the information is realized. The entirety of the image information may be present in one storage medium while only authorized users may access all of the image data present. The above mentioned European publication does not serve to accomplish a directed marking of e.g. image information for a future identification; it merely serves to encrypt the entire information content of an image so that unauthorized users do not gain access to the information.
DISCLOSURE OF THE INVENTION
The invention comprises a procedure for marking binary coded data sets, particularly but not limited to image data and audio signals by embedding at least one information unit in a data set in such a way as to embed information serving to uniquely identify the data set to be protected so that the relationship between the data set and the embedded information is not lost in a number of modifications of the data set. The identification procedure shall offer the creator as well as the customers and distributors of multimedia creations the opportunity to confirm and prove the possession of intellectual property rights to the data as well as supply proofs of abuse of the multimedia data.
The invention of the procedure for marking binary data, particularly but not limited to image data or audio signals, comprises the generation of a discrete position sequence for the integration of information units in the data set to be marked which is dependent on features specific to the data to be marked as well as on a key, and the subsequent reading or writing of the integrated (resp. to be integrated) information units in the predetermined position sequence in the data set.
The invention also comprises the embedding of additional secret, hidden data in a robust fashion in multimedia data, i.e. particularly digital images. The same procedure can also be used for marking audio signals which are structured in time and not in pixel values.
The invention, apart from the use in color, greyscale and bilevel still images, also comprises the use with digital video data, i.e. image sequences. The embedding of the additional information does not lead to a visible degradation of the image quality. The embedded information can be reconstructed given the knowledge of a possibly secret key.
The first step in the procedure described is the generation of a pseudo-random position sequence which is used to determine the positions in which a code or more generally an information unit is embedded. Characteristic information, which may for instance be extracted from the image data itself are used in combination with a secret key as a seed value for the position generation. In a second step the information unit is either read or written in the positions determined by the positions sequence. There exist different methods for reading and writing of the information units depending on the type of image data representation.
Generally speaking there are three distinguishable marking techniques which depend on the data sets to be marked.
A. Frequency Based Marking for Color and Greyscale Images
This technique is based on the idea that typical digital images of humans, buildings, natural scenery etc. may be considered as non-stationary statistical processes which are highly redundant and tolerant
Koch Eckhard
Zhao Jian
Fraunhofer Gesellschaft zur Foerderung der angewandten Forschung
Peeso Thomas R.
LandOfFree
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