A Hybrid Cryptographic System for Secured Device to Device Communication

It is general fact that even after enormous expansion of wireless communication there are still dead regions that hampers the effective communication. With exponential rise in the smart phones, a new layer of communication has evolved that could address the concerns of dead regions and capacity barriers. D2D is the evolving communication technology which focuses on short distance hops between the public devices to reach the destination. The major drawback of this technology is that most of the devices are public hence trustworthiness of the entire channel needs to be addressed in order to make it a viable solution. In this paper, we introduce a novel hybrid cryptographic approach that could address multiple eavesdroppers’ scenario. This approach incorporates both Huffman coding and Binary coding to enhance the crypto benefits for the information transmitted over D2D channel that consists of several public devices. The dual-crypto nature of the proposed algorithm offers higher efficiency, better security and improved key transmission.  Thus, the proposed hybrid cryptographic approach is robust in nature while easy and simple to operate. In addition, the proposed approach could recover the original information without any distortion from the encrypted data making the approach lossless in nature. Further simulation results prove that the proposed offers confidentiality to the transmitted to data while addressing the network capacity crunch

Efficient public-key cryptography with bounded leakage and tamper resilience

We revisit the question of constructing public-key encryption and signature schemes with security in the presence of bounded leakage and tampering memory attacks. For signatures we obtain the first construction in the standard model; for public-key encryption we obtain the first construction free of pairing (avoiding non-interactive zero-knowledge proofs). Our constructions are based on generic building blocks, and, as we show, also admit efficient instantiations under fairly standard number-theoretic assumptions. The model of bounded tamper resistance was recently put forward by Damgård et al. (Asiacrypt 2013) as an attractive path to achieve security against arbitrary memory tampering attacks without making hardware assumptions (such as the existence of a protected self-destruct or key-update mechanism), the only restriction being on the number of allowed tampering attempts (which is a parameter of the scheme). This allows to circumvent known impossibility results for unrestricted tampering (Gennaro et al., TCC 2010), while still being able to capture realistic tampering attack

Continuous Non-Malleable Key Derivation and Its Application to Related-Key Security

Related-Key Attacks (RKAs) allow an adversary to observe the outcomes of a cryptographic primitive under not only its original secret key e.g., $s$, but also a sequence of modified keys $\phi(s)$, where $\phi$ is specified by the adversary from a class $\Phi$ of so-called Related-Key Derivation (RKD) functions. This paper extends the notion of non-malleable Key Derivation Functions (nm-KDFs), introduced by Faust et al. (EUROCRYPT\u2714), to \emph{continuous} nm-KDFs. Continuous nm-KDFs have the ability to protect against any a-priori \emph{unbounded} number of RKA queries, instead of just a single time tampering attack as in the definition of nm-KDFs. Informally, our continuous non-malleability captures the scenario where the adversary can tamper with the original secret key repeatedly and adaptively. We present a novel construction of continuous nm-KDF for any polynomials of bounded degree over a finite field. Essentially, our result can be extended to richer RKD function classes possessing properties of \emph{high output entropy and input-output collision resistance}. The technical tool employed in the construction is the one-time lossy filter (Qin et al. ASIACRYPT\u2713) which can be efficiently obtained under standard assumptions, e.g., DDH and DCR. We propose a framework for constructing $\Phi$-RKA-secure IBE, PKE and signature schemes, using a continuous nm-KDF for the same $\Phi$-class of RKD functions. Applying our construction of continuous nm-KDF to this framework, we obtain the first RKA-secure IBE, PKE and signature schemes for a class of polynomial RKD functions of bounded degree under \emph{standard} assumptions. While previous constructions for the same class of RKD functions all rely on non-standard assumptions, e.g., $d$-extended DBDH assumption

Non-Malleable Functions and Their Applications

We formally study ``non-malleable functions\u27\u27 (NMFs), a general cryptographic primitive which simplifies and relaxes ``non-malleable one-way/hash functions\u27\u27 (NMOWHFs) introduced by Boldyreva et al. (Asiacrypt 2009) and refined by Baecher et al. (CT-RSA 2010). NMFs focus on basic functions, rather than one-way/hash functions considered in the literature of NMOWHFs. We mainly follow Baecher et al. to formalize a game-based definition for NMFs. Roughly, a function $f$ is non-malleable if given an image $y^* \leftarrow f(x^*)$ for a randomly chosen $x^*$, it is hard to output a mauled image $y$ with a transformation $\phi$ from some prefixed transformation class s.t. $y = f(\phi(x^*))$. A distinctive strengthening of our non-malleable notion is that $\phi$ such that $\phi(x^*) = x^*$ is allowed. We also consider adaptive non-malleability, which stipulates that non-malleability holds even when an inversion oracle is available. We investigate the relations between non-malleability and one-wayness in depth. In non-adaptive setting, we show that for any achievable transformation class, non-malleability implies one-wayness for poly-to-one functions but not vise versa.In adaptive setting, we show that for most algebra-induced transformation class, adaptive non-malleability (ANM) is equivalent to adaptive one-wayness (AOW) for injective functions. These results establish theoretical connections between non-malleability and one-wayness for functions, which extend to trapdoor functions as well, and thus resolve the open problems left by Kiltz et al. (Eurocrypt 2010). We also study the relations between standard OW/NM and hinted OW/NM, where the latter notions are typically more useful in practice. Towards efficient realizations of NMFs, we give a deterministic construction from adaptive trapdoor functions and a randomized construction from all-but-one lossy functions and one-time signature. This partially solves an open problem posed by Boldyreva et al. (Asiacrypt 2009). Finally, we explore applications of NMFs in security against related-key attacks (RKA). We first show that the implication AOW $\Rightarrow$ ANM provides key conceptual insight into addressing non-trivial copy attacks in RKA security. We then show that NMFs give rise to a generic construction of continuous non-malleable key derivation functions, which have proven to be very useful in achieving RKA security for numerous cryptographic primitives. Particularly, our construction simplifies and clarifies the construction by Qin et al. (PKC 2015)

Non-Malleable Codes with Split-State Refresh

Non-Malleable Codes for the split state model allow to encode a mes- sage into two parts such that arbitrary independent tampering on the parts either destroys completely the content or maintains the message untouched. If the code is also leakage resilient it allows limited independent leakage from the two parts. We propose a model where the two parts can be refreshed independently. We give an abstract framework for building codes for this model, instantiate the construc- tion under the external Diffie-Hellman assumption and give applications of such split-state refreshing. An advantage of our new model is that it allows arbitrarily many tamper attacks and arbitrarily large leakage over the life-time of the systems as long as occasionally each part of the code is refreshed. Our model also tolerates that the refreshing occasionally is leaky or tampered with

Super-Strong RKA Secure MAC, PKE and SE from Tag-based Hash Proof System

$\mathcal{F}$-Related-Key Attacks (RKA) on cryptographic systems consider adversaries who can observe the outcome of a system under not only the original key, say $k$, but also related keys $f(k)$, with $f$ adaptively chosen from $\mathcal{F}$ by the adversary. In this paper, we define new RKA security notions for several cryptographic primitives including message authentication code (MAC), public-key encryption (PKE) and symmetric encryption (SE). This new kind of RKA notions are called _super-strong_ RKA securities, which stipulate minimal restrictions on the adversary\u27s forgery or oracle access, thus turn out to be the strongest ones among existing RKA security requirements. We present paradigms for constructing super-strong RKA secure MAC, PKE and SE from a common ingredient, namely _Tag-based Hash Proof System_ (THPS). We also present constructions for THPS based on the $k$-Linear and the DCR assumptions. When instantiating our paradigms with concrete THPS constructions, we obtain super-strong RKA secure MAC, PKE and SE schemes for the class of restricted affine functions $\mathcal{F}_{\text{raff}}$, of which the class of linear functions $\mathcal{F}_{\text{lin}}$ is a subset. To the best of our knowledge, our MACs, PKEs and SEs are the first ones possessing super-strong RKA securities for a non-claw-free function class $\mathcal{F}_{\text{raff}}$ in the standard model and under standard assumptions. Our constructions are free of pairing and are as efficient as those proposed in previous works. In particular, the keys, tags of MAC and ciphertexts of PKE & SE all consist of only a constant number of group elements