Digital watermarking is a promising solution to video game piracy. In this paper, based on the analysis of special challenges and requirements in terms of watermarking textures in video games, a novel watermarking scheme for DDS textures in video games is proposed. To meet the performance requirements in video game applications, the proposed algorithm embeds the watermark message directly in the compressed stream in DDS files and can be straightforwardly applied in watermark container technique for real-time embedding. Furthermore, the embedding approach achieves high watermark payload to handle collusion secure fingerprinting codes with extreme length. Hence, the scheme is resistant to collusion attacks, which is indispensable in video game applications. The proposed scheme is evaluated in aspects of transparency, robustness, security and performance. Especially, in addition to classical objective evaluation, the visual quality and playing experience of watermarked games is assessed subjectively in game playing.
3D models and applications are of utmost interest in both science and industry. With the increment of their usage, their number and thereby the challenge to correctly identify them increases. Content identification is commonly done by cryptographic hashes. However, they fail as a solution in application scenarios such as computer aided design (CAD), scientific visualization or video games, because even the smallest alteration of the 3D model, e.g. conversion or compression operations, massively changes the cryptographic hash as well. Therefore, this work presents a robust hashing algorithm for 3D mesh data. The algorithm applies several different bit extraction methods. They are built to resist desired alterations of the model as well as malicious attacks intending to prevent correct allocation. The different bit extraction methods are tested against each other and, as far as possible, the hashing algorithm is compared to the state of the art. The parameters tested are robustness, security and runtime performance as well as False Acceptance Rate (FAR) and False Rejection Rate (FRR), also the probability calculation of hash collision is included. The introduced hashing algorithm is kept adaptive e.g. in hash length, to serve as a proper tool for all applications in practice.
The publishers of video games suffer from illegal piracy and information leakage caused by end-consumers, "release groups" or insiders shortly after or even before the official release of a new video game. Mechanisms to prevent or at least postpone this illegal redistribution are DRM or copy protection mechanisms. However, these mechanisms are very unpopular, because they restrict the customers in playing the game and demand a high administration effort from the developers and/or distributors. Even worse, most copy protection mechanisms have proven to be insecure as "patches" for circumvention usually are available quickly and easy to get. To satisfy the challenges of security and usability, this work introduces the idea of using digital watermarking to protect all available and suitable media types and software binaries contained in a video game. A three-layered watermarking deployment approach along the production chain is proposed to detect leakage in the release phase as well as during the development process of a boxed video game. The proposed approach features both copyright watermarking and collusion secure fingerprints embedded as transaction watermark messages in components of video games. We discuss the corresponding new challenges and opportunities. In addition, a prototype watermarking algorithm is presented to demonstrate the adaption necessity of classical image watermarking when applied to video games to satisfy the requirements for transparency, security as well as performance. The watermark capacity is significantly increased while inter-media and inter-file embedding is enabled and the associated synchronization challenge is solved by robust hashes.
We introduce an approach for verifying the integrity of digital audio recording by means of content-based integrity
watermarking. Here an audio fingerprint is extracted from the Fourier domain and embedded as a digital watermark in
the same domain. The design of the feature extraction allows a fine temporal resolution of the verification of the
integrity. Experimental results show a good distinction between authentic and tampered audio content.
Digital audio watermarking detection is often computational complex and requires at least as much audio information as
required to embed a complete watermark. In some applications, especially real-time monitoring, this is an important
drawback. The reason for this is the usage of sync sequences at the beginning of the watermark, allowing a decision
about the presence only if at least the sync has been found and retrieved. We propose an alternative method for detecting
the presence of a watermark. Based on the knowledge of the secret key used for embedding, we create a mark for all
potential marking stages and then use a sliding window to test a given audio file on the presence of statistical
characteristics caused by embedding. In this way we can detect a watermark in less than 1 second of audio.
Forensic analysis of image sets today is most often done with the help of cryptographic hashes due to their efficiency,
their integration in forensic tools and their excellent reliability in the domain of false detection alarms. A drawback of
these hash methods is their fragility to any image processing operation. Even a simple re-compression with JPEG results
in an image not detectable. A different approach is to apply image identification methods, allowing identifying illegal
images by e.g. semantic models or facing detection algorithms. Their common drawback is a high computational
complexity and significant false alarm rates. Robust hashing is a well-known approach sharing characteristics of both
cryptographic hashes and image identification methods. It is fast, robust to common image processing and features low
false alarm rates. To verify its usability in forensic evaluation, in this work we discuss and evaluate the behavior of an
optimized block-based hash.
Proc. SPIE. 8303, Media Watermarking, Security, and Forensics 2012
KEYWORDS: Transparency, Detection and tracking algorithms, Forensic science, Digital watermarking, Information technology, Multimedia, Electronic imaging, Information security, Current controlled current source
Digital transaction watermarking today is a widely accepted mechanism to discourage illegal distribution of
multimedia. The transaction watermark is a user-specific message that is embedded in all copies of one content
and thus makes it individual. Therewith it allows to trace back copyright infringements. One major threat on
transaction watermarking are collusion attacks. Here, multiple individualized copies of the work are compared
and/or combined to attack the integrity or availability of the embedded watermark message. One solution to
counter such attacks are mathematical codes called collusion secure fingerprinting codes. Problems arise when
applying such codes to multimedia files with small payload, e.g. short audio tracks or images. Therefore the
code length has to be shortened which increases the error rates and/or the effort of the tracing algorithm. In this
work we propose an approach whether to use as an addition to probabilistic fingerprinting codes for a reduction
of the effort and increment of security, as well as a new separate method providing shorter codes at a very fast
and high accurate tracing algorithm.
We present two approaches to robust image obfuscation based on permutation of image regions and channel
intensity modulation. The proposed concept of robust image obfuscation is a step towards end-to-end security in
Web 2.0 applications. It helps to protect the privacy of the users against threats caused by internet bots and web
applications that extract biometric and other features from images for data-linkage purposes. The approaches
described in this paper consider that images uploaded to Web 2.0 applications pass several transformations, such
as scaling and JPEG compression, until the receiver downloads them. In contrast to existing approaches, our
focus is on usability, therefore the primary goal is not a maximum of security but an acceptable trade-off between
security and resulting image quality.
Robustness against distortions caused by common image processing is one of the essential properties for image
watermarking to be applicable in real-world applications. Typical distortions include lossy JPEG compression, filtering,
cropping, scaling, rotation, and so on, among which geometric distortion is more challenging. Even slight geometric
distortion can totally fail the watermark detection through de-synchronization. Another important property is the
watermark payload. Although one-bit watermark is widely used in research work for algorithm testing and evaluation,
only checking whether a specific watermark exists does not meet the requirement of many practical applications. This
paper presents a practical robust image watermarking algorithm which combines template embedding and patchwork
watermarking in Fourier domain. The embedded template enables the necessary robustness against geometric distortions
and the patchwork approach provides a reasonable watermark payload which can meet the requirement of most
applications. A spatial perceptual mask is used to reshape the embedded energy after it is inverted to the spatial domain,
which significantly improves the image quality and enhances the robustness of both template and watermark.
Implementation issues and solutions, e.g. fine-tuning of embedding energy of individual pixels, are also discussed.
Experimental results demonstrate the effectiveness and practicability of the proposed algorithm.
Digital transaction watermarking today is a widely accepted mechanism to trace back copyright infringements.
Here, copies of a work are individualized by embedding user-specific watermark messages. One major threat on
transaction watermarking are collusion attacks. Here, multiple individualized copies of the work are compared
and/or combined to attack the integrity or availability of the embedded watermark message. In this work, we
show how Patchwork embedding can be adapted to provide a maximum of resistance against collusion attacks
at reduced payload and improved robustness.
We identify which hash function has the best characteristics for various applications. In some of those the
computation speed may be the most important, in others the ability to distinguish similar images, and sometimes
the robustness of the hash against attacks is the primary goal. We compare the hash functions and provide test
results. The block mean value based image hash function outperforms the other hash functions in terms of
speed. The discrete cosine transform (DCT) based image hash function is the slowest. Although the Marr-
Hildreth operator based image hash function is neither the fastest nor the most robust, it offers by far the
best discriminative abilities. Interestingly enough, the performance in terms of discriminative ability does not
depend on the content of the images. That is, no matter whether the visual appearance of the images compared
was very similar or not, the performance of the particular hash function did not change significantly. Different
image operations, like horizontal flipping, rotating or resizing, were used to test the robustness of the image hash
functions. An interesting result is that none of the tested image hash function is robust against flipping an image
Digital audio watermarking today is robust to many common attacks, including lossy compression and digital-to-analogue
conversion. One robustness and security challenge, still, is time-stretching. This operation speeds up or slows
down the playback speed while preserving the tone pitch. Although inaudible for an uninformed listener if smoothly
applied, time-stretching can be confusing for a blind watermark detection algorithm. We introduce a non-blind approach
for reconstructing the original timing based on dynamic time warping. Our experiments show that the approach is
successful even if non-linear stretching was applied. Our solution can significantly increase the robustness and security
of every audio watermarking scheme that is dependent on precise timing conditions at detection time.
Digital watermarking has become a widely used security technology in the domain of digital rights management
and copyright protection as well as in other applications. In this work, we show recent results regarding a
particular security attack: Embedding a new message in a previously watermarked cover using the same key as
the original message.
This re-embedding can be the consequence of the absence of truly asymmetric watermarking solutions, especially
if the watermark is to be detected in public. In public detection scenarios, every detector needs the same
key the embedder used to watermark the cover. With knowledge of the embedding algorithm, everybody who is
able to detect the message can also maliciously embed a new message with the same key over the old one. This
scenario is relevant in the case that an attacker intends to counterfeit a copyright notice, transaction ID or to
change an embedded authentication code.
This work presents experimental results on mechanisms for identifying such multiple embeddings in a spreadspectrum
patchwork audio watermarking approach. We demonstrate that under certain circumstances such
multiple embedding can be detected by watermarking-forensics.
Semi-fragile video watermarking is a technology for detecting manipulations. It provides robustness against
content-preserving manipulations as well as sensitivity to
content-changing manipulations. To achieve this,
robust content-describing features are applied. We use the SIFT keypoint detection as feature for our semifragile
video watermarking scheme introduced in this work. SIFT (Scale Invariant Feature Transformation)
detects points invariant to image scale and rotation and can be used for object matching after changing the 3D
viewpoint, addition of noise and modifications in illumination. With the detected feature points we generate
an authentication message, which is embedded with a robust video watermark. In the verification process we
introduce a temporal filtering approach to reduce the distortions caused by content-preserving manipulations.
We present experimental results demonstrating the robustness and sensitivity of our scheme.
Multimedia forensics deals with the analysis of multimedia data to gather information on its origin and authenticity. One
therefore needs to distinguish classical criminal forensics (which today also uses multimedia data as evidence) and
multimedia forensics where the actual case is based on a media file. One example for the latter is camera forensics where
pixel error patters are used as fingerprints identifying a camera as the source of an image. Of course multimedia forensics
can become a tool for criminal forensics when evidence used in a criminal investigation is likely to be manipulated. At
this point an important question arises: How reliable are these algorithms? Can a judge trust their results? How easy are
they to manipulate? In this work we show how camera forensics can be attacked and introduce a potential
countermeasure against these attacks.
Changing the distribution channel of movies from analogue to digital provides new perspectives and possibilities for
applying digital watermarking as security mechanisms. Digital watermarking provides its best security options when
used for individual marking of copies to trace back distribution leaks. For analogue copies, protecting movies with
individual watermarks was only cost-effective for small sets of copies as in promotional copies as duplication is done in
an automated photo-optical way. Modifications of the analogue copies only provide relatively crude approaches of
individual marking. Digital copies on the other hand can easily be modified before, during or even after distribution to
cinemas. It is also possible to embed watermarks at all of these stages to secure the complete distribution chain from
studio to cinema. In our paper we discuss two watermarking strategies suitable for different applications in the digital
cinema domain, video and still image watermarking. We provide technical background and also discuss the interference
of applying both algorithms at the same time.
Current systems and protocols based on cryptographic methods for integrity and authenticity verification of media
data do not distinguish between legitimate signal transformation and malicious tampering that manipulates the
content. Furthermore, they usually provide no localization or assessment of the relevance of such manipulations
with respect to human perception or semantics. We present an algorithm for a authentication audio watermarking
that uses a perception-based robust hash function in combination with robust watermarking to verify the integrity
of audio recordings. Experimental results show that the proposed system provides both a high level of distinction
between perceptually different audio data and a high robustness against signal transformations that do not change
the perceived information.
As digital watermarking becomes an accepted and widely applied technology, a number of concerns regarding its
reliability in typical application scenarios come up. One important and often discussed question is the robustness of
digital watermarks against multiple embedding. This means that one cover is marked several times by various users with
by same watermarking algorithm but with different keys and different watermark messages. In our paper we discuss the
behavior of our PCM audio watermarking algorithm when applying multiple watermark embedding. This includes
evaluation of robustness and transparency. Test results for multiple hours of audio content ranging from spoken words to
music are provided.
Proc. SPIE. 6819, Security, Forensics, Steganography, and Watermarking of Multimedia Contents X
KEYWORDS: Detection and tracking algorithms, Digital watermarking, Computer programming, Feature extraction, Multimedia, Acoustics, Error control coding, Signal detection, Information security, Computer security
Current systems and protocols based on cryptographic methods for integrity and authenticity verification of media
data do not distinguish between legitimate signal transformation and malicious tampering that manipulates the
content. Furthermore, they usually provide no localization or assessment of the relevance of such manipulations
with respect to human perception or semantics. We present an algorithm for a robust message authentication code
in the context of content fragile authentication watermarking to verify the integrity of audio recodings by means
of robust audio fingerprinting. Experimental results show that the proposed algorithm provides both a high level
of distinction between perceptually different audio data and a high robustness against signal transformations that
do not change the perceived information. Furthermore, it is well suited for the integration in a content-based
authentication watermarking system.
When transaction watermarking is used to secure sales in online shops by embedding
transaction specific watermarks, the major challenge is embedding efficiency:
Maximum speed by minimal workload. This is true for all types of media. Video
transaction watermarking presents a double challenge. Video files not only are larger
than for example music files of the same playback time. In addition, video
watermarking algorithms have a higher complexity than algorithms for other types of
media. Therefore online shops that want to protect their videos by transaction
watermarking are faced with the problem that their servers need to work harder and
longer for every sold medium in comparison to audio sales. In the past, many
algorithms responded to this challenge by reducing their complexity. But this usually
results in a loss of either robustness or transparency.
This paper presents a different approach. The container technology separates
watermark embedding into two stages: A preparation stage and the finalization stage.
In the preparation stage, the video is divided into embedding segments. For each
segment one copy marked with "0" and anther one marked with "1" is created. This
stage is computationally expensive but only needs to be done once. In the finalization
stage, the watermarked video is assembled from the embedding segments according
to the watermark message. This stage is very fast and involves no complex
computations. It thus allows efficient creation of individually watermarked video files.
Synchronization is still one of the most important issues in digital watermarking. Many attacks do not remove the
watermark from the cover, but only disable the synchronization between the watermark and the detector. Most
watermarking algorithms feature some synchronization strategy, but especially in audio watermarking this may not be
sufficient to fight de-synchronization attacks: As the watermark is embedded over a given length of audio data, a good
synchronization at the starting point of the retrieval process may be lost during retrieval. An example for this is time
stretching, where the effects of playback speed modification sums up during retrieval. We introduce a novel
synchronization approach applying passive audio fingerprinting to synchronize each watermarking bit individually.
Storage of the fingerprint values is not necessary in our approach, improving the usability compared to existing solutions
in this area.
Most of the MPEG watermarking schemes can only be embedded into I-frames. The other frames will not be marked.
Different attacks like frame rate changing can change the frame type of the marked I-frames. Thus the watermark could
be detected from wrong I-frames.
Due to these attacks an important issue of digital watermarking solutions for MPEG video is the temporal
synchronization of the video material to the proportions before the attacks to detect the watermark successfully. The
synchronization information can be embed as part of the information watermark or as a second watermark. The
weakness point is with the destruction of the synchronization information the watermark can not be detected more.
We provide a solution which analyzes the I-frames based on a robust image hash system. The hash solution was
developed for JPEG images and can also be used for MPEG I-frames because of their similar structure. The hash values
are robust against common manipulations, like compression, and can be used to detect the marked frames also after
manipulations at the video material. We analyze the usability of the image hash system and develop a concept based on
video and MPEG properties.
Current systems and protocols for integrity and authenticity verification of media data do not distinguish between
legitimate signal transformation and malicious tampering that manipulates the content. Furthermore, they
usually provide no localization or assessment of the relevance of such manipulations with respect to human
perception or semantics. We present an algorithm for a robust message authentication code (RMAC) to verify the
integrity of audio recodings by means of robust audio fingerprinting and robust perceptual hashing. Experimental
results show that the proposed algorithm provides both a high level of distinction between perceptually different
audio data and a high robustness against signal transformations that do not change the perceived information.
In our paper we discuss and compare the possibilities and shortcomings of both content-fragile watermarking and
digital forensics and analyze if the combination of both techniques allows the identification of more than the sum
of all manipulations identified by both techniques on their own due to synergetic effects. The first part of the
paper discusses the theoretical possibilities offered by a combined approach, in which forensics and watermarking
are considered as complementary tools for data authentication or deeply combined together, in order to reduce
their error rate and to enhance the detection efficiency. After this conceptual discussion the paper proposes
some concrete examples in which the joint approach is applied to video authentication. Some specific forensics
techniques are analyzed and expanded to handle efficiently video data. The examples show possible extensions
of passive-blind image forgery detection to video data, where the motion and time related characteristics of video
are efficiently exploited.
There are several scenarios where the integrity of digital images and videos has to be verified. Examples can be found in videos captured by surveillance cameras. In this paper we propose a semi-fragile watermarking scheme, which can be applied on still images as well as on digital videos. We concentrate on the protection of I-frames in compressed MPEG-1/2 videos. We use the entropy of the probability distribution of gray level values in block groups to generate a binary feature mask, which is embedded robustly into an adjacent I-frame. The approach can distinguish between content-preserving and content-changing manipulations. Positions of content-changing manipulations can be localized. We provide experimental results to analyze the effectiveness of the scheme. In the evaluation part we concentrate on the robustness against content-preserving and the sensitivity to content-changing manipulations.
Most of the MPEG watermarking schemes can only be embedded into I-frames. The other frames will not be marked. Different attacks like frame rate changing can change the frame type of the marked I-frames. Thus the watermark could be detected from wrong I-frames. Due to these attacks an important issue of digital watermarking solutions for MPEG video is the temporal synchronization of the video material to the proportions before the attacks to detect the watermark successfully. The synchronization information can be embed as part of the information watermark or as a second watermark. The weakness point is with the destruction of the synchronization information the watermark can not be detected more. We provide a solution which analyzes the I-frames based on a robust image hash system. The hash solution was developed for JPEG images and can also be used for MPEG I-frames because of their similar structure. The hash values are robust against common manipulations, like compression, and can be used to detect the marked frames also after manipulations at the video material. We analyze the usability of the image hash system and develop a concept based on video and MPEG properties.
Customer identification watermarking today is one of the most promising application domains of digital watermarking. It enables to identify individual copies of otherwise indistinguishable digital copies. If done without any precautions, those individual watermarking are vulnerable to a number of specialized attacks based on an attacker collecting more than one individual copy. Fingerprinting algorithms are used to create watermarks robust against these attacks, but the resulting watermarks require a high payload of the watermarking algorithm. As soon as a large number of copies need to be distinguished and more than two copies are available to the attacker, the watermarks are too long to be embedded with current algorithms. We present a novel alternative method to fight attacks aimed at individual customer identification watermarks. This is achieved by modifying the watermarked material in a way collusion attacks produce artifacts which significantly reduce the perceived quality while they do not affect the quality of the individual copies.
Today two technologies are applied when protecting audio data in digital rights management (DRM) environments: Encryption and digital watermarking. Encryption renders the data unreadable for those not in the possession of a key enabling decryption. This is especially of interest for access control, as usage of the audio data is restricted to those owning a key. Digital watermarking adds additional information into an audio file without influencing quality our file size. This additional information can be used for inserting copyright information or a customer identity into the audio file. The later method is of special interest for DRM as it is the only protection mechanism enabling tracing illegal usage to a certain customer even after the audio data has escaped the secure DRM environment. Existing methods combine these methods in first embedding the watermark and than encrypting the content. As a more efficient alternative, we introduce a combined watermarking and encryption scheme where both mechanisms are transparent to each other. A watermark is embedded in and detected from an encrypted or unencrypted file. The watermark also does not influence the encryption mechanism. The only requirement for this method is a common key available to both algorithms.
In this article we present a semi-fragile watermarking scheme for authenticating intra-coded frames in compressed digital videos. The scheme provides the detection of content-changing manipulations while being moderately robust against content-preserving manipulations. More generally, we mean by content-preserving manipulations those, which are applied in post-production processes, such as compression. Content-changing manipulations remove or insert objects into frames or sequences of frames. We focus in this work on a semi-fragile watermarking method based on invariant features referred to as points of interests. The features are extracted using the Moravec-Operator. The interest point operator of Moravec is totally un-supervised and does not require any a priori knowledge in the class of objects being protected in a given frame. Out of the interest points we generate a binary mask, which will be embedded robustly as watermark into the video. In the verification process we compare the detected watermark with the points of interest from the video, which has to be verified. We present test results evaluating the robustness against content-preserving manipulations and the fragility regarding content-changing manipulations. Beside the discussion of the results we propose a procedure to provide security of the scheme against forgery attacks.
Proc. SPIE. 5681, Security, Steganography, and Watermarking of Multimedia Contents VII
KEYWORDS: Image compression, Detection and tracking algorithms, Visualization, Video, Digital watermarking, Computer programming, Directed energy weapons, Video compression, Video processing, Signal detection
Most of the MPEG watermarking schemes are intracoded block based solutions. In a standard encoded MPEG video every 12th frame is an I-frame, consisting of intracoded blocks. The other frames will not be marked. I-frames have nearly the same structure as JPEG images and JPEG based watermarking solution are applicable for I-frames. Different attacks like frame rate changing can change the frame type of the marked I-frames. Thus the watermark can be detected from wrong I-frames and the capacity of the watermark solutions are lowly.
We propose an extended approach of an existing I-frame watermark solution. We embed the watermark also into the intercoded blocks of P- and B-frames. First the transferred intracoded watermark will be compensated by the drift compensation signal in the intercoded blocks. After this the same watermark information can be embedded in the P- and B-frames as in the I-frames. The advantages of this solution are a higher capacity and a good visual quality of the watermark solution.
We present the drawback points of existing intracoded solutions, our newly developed concept and provide the first test results.
This paper presents a new content-fragile watermarking algorithm for the detection and localization of malicious manipulations of MPEG-I/II videos. While being fragile to malicious manipulations, the watermarking scheme is robust against content-preserving manipulations like re-encoding processes. It is a bitstream watermarking method based on 8x8 DCT blocks. One of the main advantages of our scheme is the possibility of localizing positions within the video where modifications occurred. Another main advantage is the portability of the scheme to other multimedia documents based on the 8x8 DCT block domain, e.g. JPEG images. The framework of the watermarking scheme can be divided into three main parts: watermark construction, watermark embedding and watermark detection. We derive a Content Based Message (CBM) from the multimedia document, based on a partial energy relationship between two groups of DCT blocks. Embedding the CBM is based on the Differential Energy Watermarking (DEW) concept. In the detection process we compare the CBM and the retrieved watermark to detect and locate manipulations. Besides the algorithm we present experimental results to demonstrate the feasibility of the scheme. We discuss four experiments representing four typical kinds of malicious manipulations.
Proc. SPIE. 5306, Security, Steganography, and Watermarking of Multimedia Contents VI
KEYWORDS: Signal to noise ratio, Transparency, Image compression, Detection and tracking algorithms, Interference (communication), Distortion, Digital watermarking, Signal processing, Information security, Computer security
Digital watermarking is envisaged as a potential technology for copyright protection and manipulation recognition. A key issue in the usage of robust watermarking is the evaluation of robustness and security. StirMark Benchmarking has been taken to set a benchmarking suite for audio watermarking in addition to existing still image evaluation solutions. In particular we give an overview of recent advancements and actual questions in robustness and transparency evaluations, in complexity and performance issues, in security and capacity questions. Further more we introduce benchmarking for content-fragile watermarking by summarizing design aspects and concluding essential benchmarking requirements.
Distribution via Internet is of increasing importance. Easy access,
transmission and consumption of digitally represented music is very
attractive to the consumer but led also directly to an increasing
problem of illegal copying. To cope with this problem watermarking is a promising concept since it provides a useful mechanism to track illicit copies by persistently attaching property rights information to the material. Especially for online music distribution the use of so-called transaction watermarking, also denoted with the term bitstream watermarking, is beneficial since it offers the opportunity
to embed watermarks directly into perceptually encoded material without the need of full decompression/compression. Besides the concept of bitstream watermarking, former publications presented the complexity, the audio quality and the detection performance. These results are now extended by an assessment of the robustness of such schemes. The detection performance before and after applying selected attacks is presented for MPEG-1/2 Layer 3 (MP3) and MPEG-2/4 AAC bitstream watermarking, contrasted to the performance of PCM spread spectrum watermarking.
Today a number of audio watermarking algorithms have been proposed, some of them at a quality making them suitable for commercial applications. The focus of most of these algorithms is copyright protection. Therefore, transparency and robustness are the most discussed and optimised parameters. But other applications for audio watermarking can also be identified stressing other parameters like complexity or payload. In our paper, we introduce a new mp2 audio watermarking algorithm optimised for high payload. Our algorithm uses the scale factors of an mp2 file for watermark embedding. They are grouped and masked based on a pseudo-random pattern generated from a secret key. In each group, we embed one bit. Depending on the bit to embed, we change the scale factors by adding 1 where necessary until it includes either more even or uneven scale factors. An uneven group has a 1 embedded, an even group a 0. The same rule is later applied to detect the watermark. The group size can be increased or decreased for transparency/payload trade-off. We embed 160 bits or more in an mp2 file per second without reducing perceived quality. As an application example, we introduce a prototypic Karaoke system displaying song lyrics embedded as a watermark.
Digital watermarking has become an accepted technology for enabling multimedia protection schemes. One problem here is the security of these schemes. Without a suitable framework, watermarks can be replaced and manipulated. We discuss different protocols providing security against rightful ownership attacks and other fraud attempts. We compare the characteristics of existing protocols for different media like direct embedding or seed based and required attributes of the watermarking technology like robustness or payload. We introduce two new media independent protocol schemes for rightful ownership authentication. With the first scheme we ensure security of digital watermarks used for ownership protection with a combination of two watermarks: first watermark of the copyright holder and a second watermark from a Trusted Third Party (TTP). It is based on hologram embedding and the watermark consists of e.g. a company logo. As an example we use digital images and specify the properties of the embedded additional security information. We identify components necessary for the security protocol like timestamp, PKI and cryptographic algorithms. The second scheme is used for authentication. It is designed for invertible watermarking applications which require high data integrity. We combine digital signature schemes and digital watermarking to provide a public verifiable integrity. The original data can only be reproduced with a secret key. Both approaches provide solutions for copyright and authentication watermarking and are introduced for image data but can be easily adopted for video and audio data as well.
StirMark Benchmark is a well-known evaluation tool for watermarking robustness. Additional attacks are added to it continuously. To enable application based evaluation, in our paper we address attacks against audio watermarks based on lossy audio compression algorithms to be included in the test environment. We discuss the effect of different lossy compression algorithms like MPEG-2 audio Layer 3, Ogg or VQF on a selection of audio test data. Our focus is on changes regarding the basic characteristics of the audio data like spectrum or average power and on removal of embedded watermarks. Furthermore we compare results of different watermarking algorithms and show that lossy compression is still a challenge for most of them. There are two strategies for adding evaluation of robustness against lossy compression to StirMark Benchmark: (a) use of existing free compression algorithms (b) implementation of a generic lossy compression simulation. We discuss how such a model can be implemented based on the results of our tests. This method is less complex, as no real psycho acoustic model has to be applied. Our model can be used for audio watermarking evaluation of numerous application fields. As an example, we describe its importance for e-commerce applications with watermarking security.
In this paper we introduce a new content-fragile watermarking concept for multimedia data authentication, especially for a/v data. While previous data authentication watermarking schemes address single media stream only, we discuss the requirements of multimedia protection techniques. Furthermore we introduce our new approach called 3D thumbnail cube. The main idea is based on a 3D hologram over continuing video and audio frames. Beside the data authentication, we face the owner authentication problem as second requirement for manipulation recognition. The watermark for manipulation recognition has to be created by the owner itself. The goal of owner authentication is to ensure that an entity is the one it claims to be. Therefore we introduce a key server and a biometric hash approach. We discuss several strategies and introduce a biometric based framework for owner authentication. With our presented data and owner authentication solutions we can realize an advanced security level.
Protecting the media of the future - securing the future of the media is an essential task for our new century. Security is defined by security measures, e.g. confidentiality, integrity, authenticity, and non-repudiation. Most of these measures are using watermarking techniques and cryptographic mechanisms like cipher systems, digital signature schemes, and authentication protocols. The security of these mechanisms is mainly based on the authenticity of specific data like keys and attributes - both data must be dedicated to its owner in an authentic manner. Otherwise, the authenticity of data and of owners can not be guaranteed and subsequently, the security can not be assured. Therefore in our paper we want to focus on data and entity (owner) authentication. We introduce a general framework to protect media data by combining different existing techniques: cryptographic, watermarking and biometric approaches. As an example we describe general concepts for a content-fragile watermarking approach for digital images and a generic approach for biometric authentication.
One of the main problems, which darkens the future of digital watermarking technologies, is the lack of detailed evaluation of existing marking schemes. This lack of benchmarking of current algorithms is blatant and confuses rights holders as well as software and hardware manufacturers and prevents them from using the solution appropriate to their needs. Indeed basing long-lived protection schemes on badly tested watermarking technology does not make sense. In this paper we will present the architecture of a public automated evaluation service we have developed for still images, sound and video. We will detail and justify our choice of evaluation profiles, that is the series of tests applied to different types of wa-termarking schemes. These evaluation profiles allow us to measure the reliability of a marking scheme to different levels from low to very high. Beside the known StirMark transformations, we will also detail new tests that will be included in this platform. One of them is intended to measure the real size of the key space. Indeed, if one is not careful, two different watermarking keys may produce interfering watermarks and as a consequence the actual space of keys is much smaller than it appears. Another set of tests is related to audio data and addresses the usual equalisation and normalisation but also time stretching, pitch shifting. Finally we propose a set of tests for fingerprinting applications. This includes: averaging of copies with different fingerprint, random ex-change of part between different copies and comparison between copies with selection of most/less frequently used position differences.
Digital watermarking is a technology for copyright protection and protection against unauthorized access and modification of multimedia material. The most important properties of digital watermarking techniques are robustness, security, imperceptibility/ transparency, complexity, capacity and possibility of verification. Robustness means resistance to 'blind', non-targeted modifications, or common media operations. A transparent watermark causes no artifacts or quality loss. A maximum of robustness cannot be achieved at the same time as a maximum of transparency as a higher robustness requires stronger media modifications. Transparency is based on the properties of the human visual system or the human auditory system. It is an often-neglected part of a watermarking evaluation scheme. We introduce a computer aided visual model based on a visual modulation threshold function which is used to test the degree of transparency of the watermark in watermarked multimedia material using linear system theory. We describe our test environment for the model and show how it is implemented in 5 steps representing the essential parts of the visual model: Sampling, band pass contrast response, oriented response, transducer and distance. The model takes two digital images as the input of the and returns a probability that an observer can distinguish the two pictures.
Audio and video watermarking enable the copyright protection with owner or customer authentication and the detection of media manipulations. The available watermarking technology concentrates on single media like audio or video. But the typical multimedia stream consists of both video and audio data. Our goal is to provide a solution with robust and fragile aspects to guarantee authentication and integrity by using watermarks in combination with content information. We show two solutions for the protection of audio and video data with a combined robust and fragile watermarking approach. The first solution is to insert a time code into the data: We embed a signal as a watermark to detect gaps or changes in the flow of time. The basic idea uses numbers increasing by one. If in the verification process the next number is smaller than the last one or the step is greater than one, the time flow has been changed. This is realized without the combination of video and audio data. But we can synchronize the two data streams. A time signal is only valid if the combination of audio and video signals satisfy a certain attribute. To keep the basic example: if we embed an increasing a number in the audio and a decreasing number in the video, we could test if the combination of both always equals zero. The second solution is more complex: We use watermarks to embed information in each media about the content of the other media. With the help of speech recognition technology it is possible to embed the spoken text, the content, of an audio file in the video. With an algorithm previously developed in  we extract video content representation which is embedded in the audio stream. In our paper we present the problem of copyright protection and integrity checks for combined video and audio data. We show our two solutions and discuss our results.