Communication Overhead of Network Coding Schemes Secure against Pollution Attacks

Network coding is a promising approach for increasing performance of multicast data transmission and reducing energy costs. Of course, it is essential to consider security aspects to ensure a reliable data transmission. Particularly, pollution attacks may have serious impacts in network coding since a single attacker can jam large parts of the network. Therefore, various approaches have been introduced to secure network coding against this type of attack. However, introducing security increases costs. Even though there are some performance analysis of secure schemes, to our knowledge there are no details whether these schemes are worthwhile to replace routing under the facet of efficiency. Thus, we discuss in this report parameters to assess the efficiency of secure network coding schemes. Using three network graphs, we evaluate parameters focusing on communication overhead for selected schemes. Our results show that there are still benefits in comparison to routing depending on the network topology

On the Security Notions for Homomorphic Signatures

Homomorphic signature schemes allow anyone to perform computation on signed data in such a way that the correctness of computation’s results is publicly certified. In this work we analyze the security notions for this powerful primitive considered in previous work, with a special focus on adaptive security. Motivated by the complications of existing security models in the adaptive setting, we consider a simpler and (at the same time) stronger security definition inspired to that proposed by Gennaro and Wichs (ASIACRYPT’13) for homomorphic MACs. In addition to strength and simplicity, this definition has the advantage to enable the adoption of homomorphic signatures in dynamic data outsourcing scenarios, such as delegation of computation on data streams. Then, since no existing homomorphic signature satisfies this stronger notion, our main technical contribution are general compilers which turn a homomorphic signature scheme secure under a weak definition into one secure under the new stronger notion. Our compilers are totally generic with respect to the underlying scheme. Moreover, they preserve two important properties of homomorphic signatures: context-hiding (i.e. signatures on computation’s output do not reveal information about the input) and efficient verification (i.e. verifying a signature against a program P can be made faster, in an amortized, asymptotic sense, than recomputing P from scratch)

Quasi-Adaptive NIZK for Linear Subspaces Revisited

Non-interactive zero-knowledge (NIZK) proofs for algebraic relations in a group, such as the Groth-Sahai proofs, are an extremely powerful tool in pairing-based cryptography. A series of recent works focused on obtaining very efficient NIZK proofs for linear spaces in a weaker quasi-adaptive model. We revisit recent quasi-adaptive NIZK constructions, providing clean, simple, and improved constructions via a conceptually different approach inspired by recent developments in identity-based encryption. We then extend our techniques also to linearly homomorphic structure-preserving signatures, an object both of independent interest and with many applications

Bounded Fully Homomorphic Signature Schemes

Homomorphic signatures enable anyone to publicly perform computations on signed data and produce a compact tag to authenticate the results. In this paper, we construct two bounded fully homomorphic signature schemes, as follows. \begin{itemize} \item For any two polynomials $d=d(\lambda), s=s(\lambda)$, where $\lambda$ is the security parameter. Our first scheme is able to evaluate any circuit on the signatures, as long as the depth and size of the circuit are bounded by $d$ and $s$, respectively. The construction relies on indistinguishability obfuscation and injective (or polynomially bounded pre-image size) one-way functions. \medskip \item The second scheme, removing the restriction on the size of the circuits, is an extension of the first one, with succinct verification and evaluation keys. More specifically, for an a-prior polynomial $d=d(\lambda)$, the scheme allows to evaluate any circuit on the signatures, as long as the depth of the circuit is bounded by $d$. This scheme is based on differing-inputs obfuscation and collision-resistant hash functions and relies on a technique called recording hash of circuits. \end{itemize} Both schemes enjoy the composition property. Namely, outputs of previously derived signatures can be re-used as inputs for new computations. The length of derived signatures in both schemes is independent of the size of the data set. Moreover, both constructions satisfy a strong privacy notion, we call {\em semi-strong context hiding}, which requires that the derived signatures of evaluating any circuit on the signatures of two data sets are {\em identical} as long as the evaluations of the circuit on these two data sets are the same

A Review on the Mechanism Mitigating and Eliminating Internet Crimes using Modern Technologies

There is no doubting that contemporary technology creates new hazards, and these threats are many and significant, directly harming people's lives and threatening their stability. Because of the increased use of computers and Internet-connected cellphones in recent years, the problem of cybercrime has expanded substantially. Unquestionably, this kind of crime is now a reality that jeopardizes people's reputations and lives, therefore we must be aware of it to prevent being a victim. The exponential growth in internet connectedness is closely tied to a rise in cyberattack incidences, frequently with significant consequences. Malware is the weapon of choice for carrying out malicious intent in cyberspace, whether by exploiting pre-existing flaws or exploiting the unique properties of new technology. There is an urgent need in the cybersecurity area to develop more inventive and effective virus defense techniques. To do this, we first give an overview of the most often exploited vulnerabilities in the current hardware, software, and network layers. This follows criticism of the most recent mitigation efforts and the reasons why they may or may not be helpful. Following that, We'll talk about new attack methods for cutting-edge technologies including social networking, cloud computing, mobile technology, as well as critical infrastructure. We conclude by sharing our speculative findings on potential future research avenues

Practical Homomorphic MACs for Arithmetic Circuits

Homomorphic message authenticators allow the holder of a (public) evaluation key to perform computations over previously authenticated data, in such a way that the produced tag $\sigma$ can be used to certify the authenticity of the computation. More precisely, a user knowing the secret key \sk used to authenticate the original data, can verify that $\sigma$ authenticates the correct output of the computation. This primitive has been recently formalized by Gennaro and Wichs, who also showed how to realize it from fully homomorphic encryption. In this paper, we show new constructions of this primitive that, while supporting a smaller set of functionalities (i.e., polynomially-bounded arithmetic circuits as opposite to boolean ones), are much more efficient and easy to implement. Moreover, our schemes can tolerate any number of (malicious) verification queries. Our first construction relies on the sole assumption that one way functions exist, allows for arbitrary composition (i.e., outputs of previously authenticated computations can be used as inputs for new ones) but has the drawback that the size of the produced tags grows with the degree of the circuit. Our second solution, relying on the $D$-Diffie-Hellman Inversion assumption, offers somewhat orthogonal features as it allows for very short tags (one single group element!) but poses some restrictions on the composition side

Linearly Homomorphic Structure-Preserving Signatures and Their Applications

Structure-preserving signatures (SPS) are signature schemes where messages, signatures and public keys all consist of elements of a group over which a bilinear map is efficiently computable. This property makes them useful in cryptographic protocols as they nicely compose with other algebraic tools (like the celebrated Groth-Sahai proof systems). In this paper, we consider SPS systems with homomorphic properties and suggest applications that have not been provided before (in particular, not by employing ordinary SPS). We build linearly homomorphic structure-preserving signatures under simple assumptions and show that the primitive makes it possible to verify the calculations performed by a server on outsourced encrypted data (i.e., combining secure computation and authenticated computation to allow reliable and secure cloud storage and computation, while freeing the client from retaining cleartext storage). Then, we give a generic construction of non-malleable (and actually simulation-sound) commitment from any linearly homomorphic SPS. This notably provides the first constant-size non-malleable commitment to group elements