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61
Digital signatures for the analogue radio
 in Proceedings of the 5th NASA Integrated Communications Navigation and Surveillance Conference and Workshop (ICNS
, 2005
"... The air/ground voice communication between air traffic controller and aircraft does not provide any means of automatic speaker identification and is therefore susceptible to call sign confusion and originator ambiguity. In the near future the analogue VHF radio will not disappear from avionic commun ..."
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The air/ground voice communication between air traffic controller and aircraft does not provide any means of automatic speaker identification and is therefore susceptible to call sign confusion and originator ambiguity. In the near future the analogue VHF radio will not disappear from avionic communications. With an addon to the analogue radio it is possible to automatically detect the originator of a voice message. Watermarking allows the embedding of an identification into the voice signal. The tag is ideally not audible to the human listener, but is for an electronic system clearly detectable. Requirements on the system are driven by functionality and deployment constraints. The reviewed inband modem system is in our opinion not fully compatible to the legacy radio infrastructure. The spread spectrum watermarking approach shows room for improvements in functionality and capacity. With informed embedding and known host state algorithms a new trend in watermarking promises large capacity increases.
DitherModulation Data Hiding with DistortionCompensation: Exact Performance Analysis and an Improved Detector for JPEG Attacks
 in Proc. of the IEEE International Conference on Image Processing (ICIP
, 2003
"... The binary Distortion Compensated DitherModulation (DCDM) , which can be regarded to as a baseline for quantizationbased datahiding methods, is rigorously analyzed. A novel and accurate procedure for computing the exact probability of bit error is given, as well as an approximation amenable to d ..."
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The binary Distortion Compensated DitherModulation (DCDM) , which can be regarded to as a baseline for quantizationbased datahiding methods, is rigorously analyzed. A novel and accurate procedure for computing the exact probability of bit error is given, as well as an approximation amenable to differentiation which allows to obtain the optimal weights in a newly proposed decoding structure, for significant improvements on performance. The results are particularized for a JPEG compression scenario which allows to show their usefulness. Experimental results validating the proposed theory are presented.
Spread spectrum watermarking for real images: is everything so hopeless
 in Proceedings of the European Signal Processing Conference (EUSIPCO2004
, 2004
"... In this paper we perform the capacity analysis of knownhoststatitistics watermarking methods based on spread spectrum (SS) under Additive Whight Gaussian noise (AWGN) attack. The reason of our research is based on the paradox that being noneffective in theory SSbased practical watermarking system ..."
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In this paper we perform the capacity analysis of knownhoststatitistics watermarking methods based on spread spectrum (SS) under Additive Whight Gaussian noise (AWGN) attack. The reason of our research is based on the paradox that being noneffective in theory SSbased practical watermarking systems outperform knownhoststate methods when a commonly accepted benchmarking strategy (Stirmark benchmark) is used. We show that the gap in capacity of SSbased techniques with respect to quantizationbased techniques at high WNR regime could be significantly reduced, if the embedding scenario is designed using a proper stochastic model of the host image at the encoder. We show how the practical solution of watermark power allocation problem relates to the optimal one. In particular, we model the host image as an Autoregressive Process of the first order (AR(1)) and show the results of power allocation based on the waterpouring principle. It is pointed out that watermark spectrum in a real system that is properly shaped using Contrast Sensitivity Function (CSF) wellapproximates the waterpouring solution. Finally, we perform several tests to analyze the modified SS capacity facing AWGN attack. Experimental results show that host interference in this case is significantly weakened, which leads to a noticeable capacity improvement. 1.
Zeroknowledge watermark detector robust to sensitivity attacks
 in 8th ACM Multimedia and Security Workshop
"... Current zeroknowledge watermark detectors are based on a linear correlation between the asset features and a given secret sequence. This detection function is susceptible of being attacked by sensitivity attacks, for which zeroknowledge does not provide protection. In this paper a new zeroknowled ..."
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Current zeroknowledge watermark detectors are based on a linear correlation between the asset features and a given secret sequence. This detection function is susceptible of being attacked by sensitivity attacks, for which zeroknowledge does not provide protection. In this paper a new zeroknowledge watermark detector robust to sensitivity attacks is presented, using the Generalized Gaussian Maximum Likelihood (ML) detector as basis. The inherent robustness that this detector presents against sensitivity attacks, together with the security provided by the zeroknowledge protocol that conceals the keys that could be used to remove the watermark or to produce forged assets, results in a robust and secure protocol. Additionally, two new zeroknowledge proofs for modulus and square root calculation are presented; they serve as building blocks for the zeroknowledge implementation of the Generalized Gaussian ML detector, and also open new possibilities in the design of high level protocols.
Steganalysis of QIMBased Data Hiding using Kernel Density Estimation
"... This paper presents a novel steganalysis technique to attack quantization index modulation (QIM) steganography. Our method is based on the observation that QIM embedding disturbs neighborhood correlation in the transform domain. We estimate the probability density function (pdf) of this statistical ..."
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This paper presents a novel steganalysis technique to attack quantization index modulation (QIM) steganography. Our method is based on the observation that QIM embedding disturbs neighborhood correlation in the transform domain. We estimate the probability density function (pdf) of this statistical change in a systematic manner using a kernel density estimate (KDE) method. The estimated parametric density model is then used for stego message detection. The impact of the choice of kernels on the estimated density is investigated experimentally. Simulation results evaluated on a large dataset of 6000 quantized images indicate that the proposed method is reliable. The impact of the choice of message embedding parameters on the accuracy of the steganalysis detection is also evaluated. Simulation results show that the proposed method can distinguish between the quantizedcover and the QIMstego with low false alarm rates (i.e. Pfn ≤ 0.03 and Pfp ≤ 0.19). We demonstrate that the proposed steganalysis scheme can successfully attack steganographic tools like Jsteg and JP Hide and Seek as well.
Robustness improvement of knownhoststate watermarking using host statistics
 in Proceedings of IS&T/SPIE 17th Annual Symposium: Electronic Imaging, Security, Steganography, and Watermarking of Multimedia Contents VII
, 2005
"... In this paper we consider the problem of performance improvement of knownhoststate (quantizationbased) watermarking methods undergo Additive White Gaussian noise (AWGN) and uniform noise attacks. We question the optimality of uniform highrate quantizer based design of Dither Modulation and Disto ..."
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In this paper we consider the problem of performance improvement of knownhoststate (quantizationbased) watermarking methods undergo Additive White Gaussian noise (AWGN) and uniform noise attacks. We question the optimality of uniform highrate quantizer based design of Dither Modulation and Distortion Compensated Dither Modulation methods from their robustness to these attacks point of view in terms of bit error rate probability. Motivated by the superior performance of the uniform deadzone quantizer over the uniform one in lossy source coding, we propose to replace the latter one by the former designed according to the statistics of the host data. Based on the suggested modifications we obtain analytical expressions for the bit error rate probability analysis of quantizationbased watermarking methods in AWGN and uniform noise channels. Experimental results of computer simulations demonstrate significant performance enhancement of knownhoststate watermarking techniques in comparison to the classically elaborated schemes.
Hexagonal Quantizers are not Optimal for 2D Data Hiding
 In Proc. of SPIE Vol. 5020, Security and Watermarking of Multimedia Contents IV
, 2003
"... Data hiding using quantization has revealed as an effective way of taking into account side information at the encoder. When quantizing more than one host signal samples there are two choices: 1) using the Cartesian product of several onedimensional quantizers, as made in Scalar Costa Scheme (SCS); ..."
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Data hiding using quantization has revealed as an effective way of taking into account side information at the encoder. When quantizing more than one host signal samples there are two choices: 1) using the Cartesian product of several onedimensional quantizers, as made in Scalar Costa Scheme (SCS); or 2) performing vectorial quantization. The second option seems better, as ratedistortion theory affirms that higher dimensional quantizers yield improved performance due to better spherepacking properties. Although the embedding problem does resemble that of ratedistortion, no attacks or host signal characteristics are usually considered when designing the quantizer in this way. We show that attacks worsen the performance of the a priori optimal lattice quantizer through a counterexample: the comparison under Gaussian distortion of hexagonal lattice quantization against bidimensional DistortionCompensated Quantized Projection (DCQP), a data hiding alternative based in quantizing a linear projection of the host signal. Apart from empirical comparisons, theoretical lower bounds on the probability of decoding error of hexagonal lattices under Gaussian host signal and attack are provided and compared to the already analyzed DCQP method.
Optimal Strategies For SpreadSpectrum And QuantizedProjection Image Data Hiding Games with BER Payoffs
 in Proc. of the IEEE International Conference on Image Processing (ICIP
, 2003
"... We analyze spreadspectrum and quantization projection data hiding methods from a gametheoretic point of view, using the bit error rate (BER) as the payoff, and assuming that the embedder simply follows pointbypoint constraints given by a perceptual mask, whereas for the attacker an MSElike con ..."
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We analyze spreadspectrum and quantization projection data hiding methods from a gametheoretic point of view, using the bit error rate (BER) as the payoff, and assuming that the embedder simply follows pointbypoint constraints given by a perceptual mask, whereas for the attacker an MSElike constraint is imposed. The optimal attacking and decoding strategies are obtained by making use of a theorem that in addition states that those strategies constitute an equilibrium of the game. Experimental results supporting our analyses are also shown.
Asymmetric Spread Spectrum DataHiding For Laplacian Host Data
 IEEE International Conference on Image Processing ICIP 2005
, 2005
"... Spread spectrum (SS) or knownhoststatistics technique has shown the best performance in terms of both rate of reliable communications and bit error probability at the low watermarktonoise ratio (WNR) regime. These results were obtained assuming that the host data follows an independent and ide ..."
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Spread spectrum (SS) or knownhoststatistics technique has shown the best performance in terms of both rate of reliable communications and bit error probability at the low watermarktonoise ratio (WNR) regime. These results were obtained assuming that the host data follows an independent and identically distributed (i.i.d.) Gaussian distribution. However, in some widely used in practical datahiding transform domains (like wavelet or discrete cosine transform domains) the host statistics have strong nonGaussian character. Motivated by this stochastic modeling mismatch between the used assumption and the real case, a new setup of the SSbased datahiding with Laplacian host is presented for performance enhancement in terms of both bit error probability and achievable rates in additive white Gaussian noise (AWGN) channels based on the parallel splitting of Laplacian source.
QuantizationBased Methods: Additive Attacks Performance Analysis
, 2008
"... The main goal of this study consists in the development of the worst case additive attack (WCAA) for Mary quantizationbased datahiding methods using as design criteria the error probability and the maximum achievable rate of reliable communications. Our analysis focuses on the practical scheme ..."
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The main goal of this study consists in the development of the worst case additive attack (WCAA) for Mary quantizationbased datahiding methods using as design criteria the error probability and the maximum achievable rate of reliable communications. Our analysis focuses on the practical scheme known as distortioncompensated dither modulation (DCDM). From the mathematical point of view, the problem of the worst case attack (WCA) design using probability of error as a cost function is formulated as the maximization of the average probability of error subject to the introduced distortion for a given decoding rule. When mutual information is selected as a cost function, a solution of the minimization problem should provide such an attacking noise probability density function (pdf) that will maximally decrease the rate of reliable communications for an arbitrary decoder structure. The obtained results demonstrate that, within the class of additive attacks, the developed attack leads to a stronger performance decrease for the considered class of embedding techniques than the additive white Gaussian or uniform noise attacks.