On the data hiding theory and multimedia content security applications

This dissertation is a comprehensive study of digital steganography for multimedia content protection. With the increasing development of Internet technology, protection and enforcement of multimedia property rights has become a great concern to multimedia authors and distributors. Watermarking technologies provide a possible solution for this problem. The dissertation first briefly introduces the current watermarking schemes, including their applications in video,, image and audio. Most available embedding schemes are based on direct Spread Sequence (SS) modulation. A small value pseudo random signature sequence is embedded into the host signal and the information is extracted via correlation. The correlation detection problem is discussed at the beginning. It is concluded that the correlator is not optimum in oblivious detection. The Maximum Likelihood detector is derived and some feasible suboptimal detectors are also analyzed. Through the calculation of extraction Bit Error Rate (BER), it is revealed that the SS scheme is not very efficient due to its poor host noise suppression. The watermark domain selection problem is addressed subsequently. Some implications on hiding capacity and reliability are also studied. The last topic in SS modulation scheme is the sequence selection. The relationship between sequence bandwidth and synchronization requirement is detailed in the work. It is demonstrated that the white sequence commonly used in watermarking may not really boost watermark security. To address the host noise suppression problem, the hidden communication is modeled as a general hypothesis testing problem and a set partitioning scheme is proposed. Simulation studies and mathematical analysis confirm that it outperforms the SS schemes in host noise suppression. The proposed scheme demonstrates improvement over the existing embedding schemes. Data hiding in audio signals are explored next. The audio data hiding is believed a more challenging task due to the human sensitivity to audio artifacts and advanced feature of current compression techniques. The human psychoacoustic model and human music understanding are also covered in the work. Then as a typical audio perceptual compression scheme, the popular MP3 compression is visited in some length. Several schemes, amplitude modulation, phase modulation and noise substitution are presented together with some experimental results. As a case study, a music bitstream encryption scheme is proposed. In all these applications, human psychoacoustic model plays a very important role. A more advanced audio analysis model is introduced to reveal implications on music understanding. In the last part, conclusions and future research are presented

Digital Watermarking for Verification of Perception-based Integrity of Audio Data

In certain application fields digital audio recordings contain sensitive content. Examples are historical archival material in public archives that preserve our cultural heritage, or digital evidence in the context of law enforcement and civil proceedings. Because of the powerful capabilities of modern editing tools for multimedia such material is vulnerable to doctoring of the content and forgery of its origin with malicious intent. Also inadvertent data modification and mistaken origin can be caused by human error. Hence, the credibility and provenience in terms of an unadulterated and genuine state of such audio content and the confidence about its origin are critical factors. To address this issue, this PhD thesis proposes a mechanism for verifying the integrity and authenticity of digital sound recordings. It is designed and implemented to be insensitive to common post-processing operations of the audio data that influence the subjective acoustic perception only marginally (if at all). Examples of such operations include lossy compression that maintains a high sound quality of the audio media, or lossless format conversions. It is the objective to avoid de facto false alarms that would be expectedly observable in standard crypto-based authentication protocols in the presence of these legitimate post-processing. For achieving this, a feasible combination of the techniques of digital watermarking and audio-specific hashing is investigated. At first, a suitable secret-key dependent audio hashing algorithm is developed. It incorporates and enhances so-called audio fingerprinting technology from the state of the art in contentbased audio identification. The presented algorithm (denoted as ”rMAC” message authentication code) allows ”perception-based” verification of integrity. This means classifying integrity breaches as such not before they become audible. As another objective, this rMAC is embedded and stored silently inside the audio media by means of audio watermarking technology. This approach allows maintaining the authentication code across the above-mentioned admissible post-processing operations and making it available for integrity verification at a later date. For this, an existent secret-key ependent audio watermarking algorithm is used and enhanced in this thesis work. To some extent, the dependency of the rMAC and of the watermarking processing from a secret key also allows authenticating the origin of a protected audio. To elaborate on this security aspect, this work also estimates the brute-force efforts of an adversary attacking this combined rMAC-watermarking approach. The experimental results show that the proposed method provides a good distinction and classification performance of authentic versus doctored audio content. It also allows the temporal localization of audible data modification within a protected audio file. The experimental evaluation finally provides recommendations about technical configuration settings of the combined watermarking-hashing approach. Beyond the main topic of perception-based data integrity and data authenticity for audio, this PhD work provides new general findings in the fields of audio fingerprinting and digital watermarking. The main contributions of this PhD were published and presented mainly at conferences about multimedia security. These publications were cited by a number of other authors and hence had some impact on their works

Study and Implementation of Watermarking Algorithms

Water Making is the process of embedding data called a watermark into a multimedia object such that watermark can be detected or extracted later to make an assertion about the object. The object may be an audio, image or video. A copy of a digital image is identical to the original. This has in many instances, led to the use of digital content with malicious intent. One way to protect multimedia data against illegal recording and retransmission is to embed a signal, called digital signature or copyright label or watermark that authenticates the owner of the data. Data hiding, schemes to embed secondary data in digital media, have made considerable progress in recent years and attracted attention from both academia and industry. Techniques have been proposed for a variety of applications, including ownership protection, authentication and access control. Imperceptibility, robustness against moderate processing such as compression, and the ability to hide many bits are the basic but rat..

Anonymizing Speech: Evaluating and Designing Speaker Anonymization Techniques

The growing use of voice user interfaces has led to a surge in the collection and storage of speech data. While data collection allows for the development of efficient tools powering most speech services, it also poses serious privacy issues for users as centralized storage makes private personal speech data vulnerable to cyber threats. With the increasing use of voice-based digital assistants like Amazon's Alexa, Google's Home, and Apple's Siri, and with the increasing ease with which personal speech data can be collected, the risk of malicious use of voice-cloning and speaker/gender/pathological/etc. recognition has increased. This thesis proposes solutions for anonymizing speech and evaluating the degree of the anonymization. In this work, anonymization refers to making personal speech data unlinkable to an identity while maintaining the usefulness (utility) of the speech signal (e.g., access to linguistic content). We start by identifying several challenges that evaluation protocols need to consider to evaluate the degree of privacy protection properly. We clarify how anonymization systems must be configured for evaluation purposes and highlight that many practical deployment configurations do not permit privacy evaluation. Furthermore, we study and examine the most common voice conversion-based anonymization system and identify its weak points before suggesting new methods to overcome some limitations. We isolate all components of the anonymization system to evaluate the degree of speaker PPI associated with each of them. Then, we propose several transformation methods for each component to reduce as much as possible speaker PPI while maintaining utility. We promote anonymization algorithms based on quantization-based transformation as an alternative to the most-used and well-known noise-based approach. Finally, we endeavor a new attack method to invert anonymization.Comment: PhD Thesis Pierre Champion | Universit\'e de Lorraine - INRIA Nancy | for associated source code, see https://github.com/deep-privacy/SA-toolki

Proposta e avaliação de sistema de comunicação de informação escondida em propagandas sonoras

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2014.Esta dissertação propõe um novo sistema de comunicação informado projetado para incorporar a informação escondida em anúncios de áudio. A informação é modulada e transmitida através de uma marca d'água em áudio digital incorporada ao sinal de áudio hospedeiro. A inserção de marca d'água é projetada para alcançar um impacto perceptual mínimo e alta robustez às distorções do ambiente, a fim de cumprir com a proposta de aplicação em marketing. A energia da incorporação está devidamente dimensionada para atingir a alta transparência. Novas técnicas de sincronização e de equalização adaptativa são investigadas e propostas para extrair as informações de forma confiável após as interferências do canal ambiente. Os resultados experimentais, utilizando canais ambientes simulados e reais, ilustram o desempenho do sistema proposto e os resultados estão em contraste a outras técnicas existentes. O objetivo deste trabalho é expor um sistema de marca d'água digital de áudio que integre em um sistema de comunicação informada escondida em propagandas sonoras, permitindo a utilização deste sistema em aplicações de marketing.This dissertation proposes a new informed communication system designed to embed information hidden into audio advertisements. The information is modulated and transmitted through a audio digital watermark embedded into the audio signal host. The watermark embedding is designed to achieve minimal perceptual impact and high robustness to environment distortions in order to comply with the proposed application in marketing. The embedding energy is properly scaled in order to achieve high transparency. Novel synchronization and adaptive equalization techniques are investigated and proposed to reliably extract the information after the channel interferences. Experimental results using simulated and real environment channels illustrate the performance of the proposed system and results are contrasted to other existing techniques

Recent Trends in Communication Networks

In recent years there has been many developments in communication technology. This has greatly enhanced the computing power of small handheld resource-constrained mobile devices. Different generations of communication technology have evolved. This had led to new research for communication of large volumes of data in different transmission media and the design of different communication protocols. Another direction of research concerns the secure and error-free communication between the sender and receiver despite the risk of the presence of an eavesdropper. For the communication requirement of a huge amount of multimedia streaming data, a lot of research has been carried out in the design of proper overlay networks. The book addresses new research techniques that have evolved to handle these challenges

Equalização Adaptativa Aplicada a um Sistema de Marcação de Áudio Digital

TCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia de Controle e Automação.The transmission of watermarked audio by acoustic channel is still a limited theme in literature. Few studies in this area have shown good results against this type of transmission. Even the state of the art techniches have limitations mostly related to the transparency of the mark. This work presents problems caused by acoustic reverberation in the audio broadcast as the ISI and distortion of the frequency spectrum. An adaptive equalization technique is proprosed to reduce the harmful effects of channel on watermarked audios and to improve the decoding rate. It is intended by increasing the watermarking robustness to reduce the watermark’s energy and to boost its transparency without compromising good decoding rates. The equalization is done based on the method proposed in [1] using an approximation of the transmission convolutional channel and its subsequent reversal, characterizing an zero forcing equalizer. The channel estimation is performed in small intervals of time by adaptive filtering using the watermark’s synchronization sequence itself to train the adaptive filter. Three adaptive filtering algorithms are tested: LMS, NLMS and AFA. Tests on simulated and real environment are presented comparing the decoding rates of a non equalized signal with signals that were equalized using adaptive filtering algorithms cited.A transmissão de áudios marcados digitalmente pelo meio acústico ainda é um tema limitado na literatura. Poucos trabalhos nesta área mostram bons resultados frente a este tipo de transmissão. Mesmo as técnicas de estado da arte, apresentam limitações, na maioria das vezes relacionadas à transparência da marca. Neste trabalho, são pontuados os problemas causados pela reverberação acústica no áudio transmitido, como a ISI e a distorção do espectro de frequência. Uma técnica de equalização adaptativa é proposta para reduzir os efeitos danosos do canal acústico sobre o áudio marcado e para melhorar a taxa de decodificação da informação inserida. Pretende-se através do aumento da robustez da marcação, conseguir reduzir energia da marca d’água e torná-la mais transparente, sem abrir mão de boas taxas de decodificação. A equalização é feita baseada na proposta de [1], através de uma aproximação do canal de transmissão convolutivo e sua posterior inversão, caracterizando uma equalização zero forcing. A estimação do canal é realizada em pequenos intervalos de tempo por filtragem adaptativa, utilizando-se da sequência de sincronia da própria marca d’água para treinar o filtro adaptativo. Três algoritmos de filtragem adaptativa são testados: LMS, NLMS e AFA. Testes em ambiente simulado e real são apresentados comparando o desempenho da decodificação do sinal não equalizado com os sinais equalizados utilizando-se dos algoritmos de filtragem adaptativa citados