STEGANOGRAPHIC METHODS

In this paper we analyze and test several steganographic techniques on still images. We show that embedding a large amount of data into the picture it can modify its visible properties. We compare the RSA and the elliptic curve (ECC) based digital signatures, and we analyze their advantages and disadvantages in steganography. In steganography it is important that the embedded data size should be minimized. Using ECC minimization of the embedded information is possible, because the minimal block size is smaller than in the case of RSA

Thesis Summary: Toward a theory of Steganography

Abstract Informally, steganography refers to the practice of hiding secret messages in communications over a public channel so that an eavesdropper (who listens to all communications) cannot even tell that a secret message is being sent. In contrast to the active literature proposing new concrete steganographic protocols and analysing flaws in existing protocols, there has been very little work on formalizing steganographic notions of security, and none giving complete, rigorous proofs of security in a satisfying model. This thesis initiates the study of steganography from a cryptographic point of view. We give a precise model of a communication channel and a rigorous definition of steganographic security, and prove that relative to a channel oracle, secure steganography exists if and only if one-way functions exist. We give tightly matching upper and lower bounds on the maximum rate of any secure stegosystem. We introduce the concept of steganographic key exchange and public-key steganography, and show that provably secure protocols for these objectives exist under a variety of standard number-theoretic assumptions. We consider several notions of active attacks against steganography, show how to achieve each under standard assumptions, and consider the relationships between these notions. Finally, we extend the concept of steganograpy as covert communication to include the more general concept of covert computation

On the Gold Standard for Security of Universal Steganography

While symmetric-key steganography is quite well understood both in the information-theoretic and in the computational setting, many fundamental questions about its public-key counterpart resist persistent attempts to solve them. The computational model for public-key steganography was proposed by von Ahn and Hopper in EUROCRYPT 2004. At TCC 2005, Backes and Cachin gave the first universal public-key stegosystem - i.e. one that works on all channels - achieving security against replayable chosen-covertext attacks (SS-RCCA) and asked whether security against non-replayable chosen-covertext attacks (SS-CCA) is achievable. Later, Hopper (ICALP 2005) provided such a stegosystem for every efficiently sampleable channel, but did not achieve universality. He posed the question whether universality and SS-CCA-security can be achieved simultaneously. No progress on this question has been achieved since more than a decade. In our work we solve Hopper's problem in a somehow complete manner: As our main positive result we design an SS-CCA-secure stegosystem that works for every memoryless channel. On the other hand, we prove that this result is the best possible in the context of universal steganography. We provide a family of 0-memoryless channels - where the already sent documents have only marginal influence on the current distribution - and prove that no SS-CCA-secure steganography for this family exists in the standard non-look-ahead model.Comment: EUROCRYPT 2018, llncs styl

Efficient Public Key Steganography Secure Against Adaptively Chosen Stegotext Attacks

We define the notion of adative chosen stegotext security. We then construct \emph{efficient} public key steganographic schemes secure against adaptively chosen stegotext attacks, without resort to any special existence assumption such as unbiased functions. This is the first time such a construction is obtained. Not only our constructions are \emph{secure}, but also are essentially optimal and have \emph{no error} decoding. We achieve this by applying a primitive called $\ch{P}$-codes

A Survey on IP Watermarking Techniques

Intellectual property (IP) block reuse is essential for facilitating the design process of system-on-a-chip. Sharing IP designs poses significant high security risks. Recently, digital watermarking emerged as a candidate solution for copyright protection of IP blocks. In this paper, we survey and classify different techniques used for watermarking IP designs. To this end, we defined several evaluation criteria, which can also be used as a benchmark for new IP watermarking developments. Furthermore, we established a comprehensive set of requirements for future IP watermarking techniques