157 research outputs found

    Steganography and collusion in cryptographic protocols

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (leaves 61-62).Steganography, the hiding of covert messages inside innocuous communication, is an active area of cryptographic research. Recent research has shown that provably undetectable steganography is possible in a wide variety of settings. We believe that the existence of such undetectable steganography will have far reaching implications. In this thesis, we investigate the impact of steganography on the design of cryptographic protocols. In particular, we show that that all existing cryptographic protocols allow malicious players to collude and coordinate their actions by steganographicly hiding covert messages inside legitimate protocol traffic. Such collusion is devastating in many settings, and thus we argue that it's elimination is an important direction for cryptographic research. Defeating such steganographic collusion requires not only new cryptographic protocols, but also a new notion of protocol security. Traditional notions of protocol security attempt to minimize the injuries to privacy and correctness inflicted by malicious participants who collude during run-time. They do not, however, prevent malicious parties from colluding and coordinating their actions in the first place! We therefore put forward the notion of a collusion-free protocol which guarantees that no set of players can use the protocol to maliciously coordinate their actions.(cont.) As should be expected, such a strong notion of security is very difficult to achieve. We show that achieving collusion-free security is impossible in a model with only broadcast communication and that even with physically private communication (e.g. physical envelopes) there are still many ideal functionalities that have no collusion-free protocols. Fortunately, under natural assumptions collusion-free protocols exist for an interesting class of ideal functionalities. Assuming the existence of trapdoor permutations, we construct collusion-free protocols, in a model with both broadcast messages and physical envelopes, for every finite ideal functionality in which all actions are public.by Matthew LepinskiPh.D

    Data Hiding and Its Applications

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    Data hiding techniques have been widely used to provide copyright protection, data integrity, covert communication, non-repudiation, and authentication, among other applications. In the context of the increased dissemination and distribution of multimedia content over the internet, data hiding methods, such as digital watermarking and steganography, are becoming increasingly relevant in providing multimedia security. The goal of this book is to focus on the improvement of data hiding algorithms and their different applications (both traditional and emerging), bringing together researchers and practitioners from different research fields, including data hiding, signal processing, cryptography, and information theory, among others

    On the Implementation of Spread Spectrum Fingerprinting in Asymmetric Cryptographic Protocol

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    <p/> <p>Digital fingerprinting of multimedia contents involves the generation of a fingerprint, the embedding operation, and the realization of traceability from redistributed contents. Considering a buyer's right, the asymmetric property in the transaction between a buyer and a seller must be achieved using a cryptographic protocol. In the conventional schemes, the implementation of a watermarking algorithm into the cryptographic protocol is not deeply discussed. In this paper, we propose the method for implementing the spread spectrum watermarking technique in the fingerprinting protocol based on the homomorphic encryption scheme. We first develop a rounding operation which converts real values into integer and its compensation, and then explore the tradeoff between the robustness and communication overhead. Experimental results show that our system can simulate Cox's spread spectrum watermarking method into asymmetric fingerprinting protocol.</p

    Systematic Review on Security and Privacy Requirements in Edge Computing: State of the Art and Future Research Opportunities

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    Edge computing is a promising paradigm that enhances the capabilities of cloud computing. In order to continue patronizing the computing services, it is essential to conserve a good atmosphere free from all kinds of security and privacy breaches. The security and privacy issues associated with the edge computing environment have narrowed the overall acceptance of the technology as a reliable paradigm. Many researchers have reviewed security and privacy issues in edge computing, but not all have fully investigated the security and privacy requirements. Security and privacy requirements are the objectives that indicate the capabilities as well as functions a system performs in eliminating certain security and privacy vulnerabilities. The paper aims to substantially review the security and privacy requirements of the edge computing and the various technological methods employed by the techniques used in curbing the threats, with the aim of helping future researchers in identifying research opportunities. This paper investigate the current studies and highlights the following: (1) the classification of security and privacy requirements in edge computing, (2) the state of the art techniques deployed in curbing the security and privacy threats, (3) the trends of technological methods employed by the techniques, (4) the metrics used for evaluating the performance of the techniques, (5) the taxonomy of attacks affecting the edge network, and the corresponding technological trend employed in mitigating the attacks, and, (6) research opportunities for future researchers in the area of edge computing security and privacy

    Theory and Applications of Outsider Anonymity in Broadcast Encryption

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    Broadcast Encryption (BE) allows efficient one-to-many secret communication of data over a broadcast channel. In the standard setting of BE, information about receivers is transmitted in the clear together with ciphertexts. This could be a serious violation of recipient privacy since the identities of the users authorized to access the secret content in certain broadcast scenarios are as sensitive as the content itself. Anonymous Broadcast Encryption (AnoBe) prevents this leakage of recipient identities from ciphertexts but at a cost of a linear lower bound (in the number of receivers) on the length of ciphertexts. A linear ciphertext length is a highly undesirable bottleneck in any large-scale broadcast application. In this thesis, we propose a less stringent yet very meaningful notion of anonymity for anonymous broadcast encryption called Outsider-Anonymous Broadcast Encryption (oABE) that allows the creation of ciphertexts that are sublinear in the number of receivers. We construct several oABE schemes with varying security guarantees and levels of efficiency. We also present two very interesting cryptographic applications afforded by the efficiency of our oABE schemes. The first is Broadcast Steganography (BS), the extension of the state of the art setting of point-to-point steganography to the multi-recipient setting. The second is Oblivious Group Storage (OGS), the introduction of fine-grained data access control policies to the setting of multi-client oblivious cloud storage protocols

    Steganography-Free Zero-Knowledge

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    We revisit the well-studied problem of preventing steganographic communication in multi-party communications. While this is known to be a provably impossible task, we propose a new model that allows circumventing this impossibility. In our model, the parties first publish a single message during an honest non-interactive pre-processing phase and then later interact in an execution phase. We show that in this model, it is indeed possible to prevent any steganographic communication in zero-knowledge protocols. Our solutions rely on standard cryptographic assumptions

    Kleptography trapdoor free cryptographic protocols

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    Context. Methods of known kleptography implementations are being investigated. The article focuses mostly on SETUP design of subliminal data leakage channels. Aim. Suggest approaches to develop SETUP resistant cryptosystems. Methods. The necessary conditions for SETUP implementation are building in entropy source (otherwise generated secret will be predictable). In this article, it\u27s considered subscriber whose protocol implementation is suspected to be modified by Developer (the malicious actor who is able to influence on cryptosystem implementation) to create subliminal leakage channel. The possible countermeasure is to prohibit usage own random sources for subscribers, enforce generate random values from public counters. %them to use external Trusted Random Number Generation service. Results. The formal model for basic SETUP scheme has been suggested. Approach to develop SETUP resistant protocols has been described. Two basic SETUP-resistance protocols (nonce generation protocol and Diffie-Hellman key agreement protocol) have been proposed

    Covert communication over VoIP streaming media with dynamic key distribution and authentication

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    Voice over Internet Protocol (VoIP) is widely embedded into commercial and industrial applications. VoIP streams can be used as innocuous cover objects to hide the secret data in steganographic systems. The security offered by VoIP signaling protocols is likely to be compromised due to a sharp increase in computing power. This article describes a theoretical and experimental investigation of covert steganographic communications over VoIP streaming media. A new information-theoretical model of secure covert VoIP communications was constructed to depict the security scenarios in steganographic systems against the passive attacks. A one-way accumulation-based steganographic algorithm was devised to integrate dynamic key updating and exchange with data embedding and extraction, so as to protect steganographic systems from adversary attacks. The theoretical analysis of steganographic security using information theory proves that the proposed model for covert VoIP communications is secure against a passive adversary. The effectiveness of the steganographic algorithm for covert VoIP communications was examined by means of performance and robustness measurements. The results reveal that the algorithm has no or little impact on real-time VoIP communications in terms of imperceptibility, speech quality, and signal distortion, and is more secure and effective at improving the security of covert VoIP communications than the other related algorithms with the comparable data embedding rates
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