Secure Plot Transfer for the Chia Blockchain

Chia is a popular cryptocurrency that relies on proofs of space (PoS) for consensus. Plots are the unit of storage on Chia and form the basis of PoS generation. When a proof is found that meets the challenge requirements, farmers on the network compete to create blocks. Plot generation and farming involve the use of secret information, which makes plot transfer a non-trivial task in Chia. In this short note, we propose a way to transfer Chia plots in a secure manner with the help of zero-knowledge proofs

Cryptographic agents

Over the last decade or so, thanks to remarkable breakthroughs in cryptographic techniques, a wave of ''cryptographic objects'' -- identity-based encryption, fully-homomorphic encryption, functional encryption, and most recently, various forms of obfuscation -- have opened up exciting new possibilities for computing on encrypted data. Initial foundational results on this front consisted of strong impossibility results. Breakthrough constructions, as they emerged, often used specialized security definitions which avoided such impossibility results. However, as these objects and their constructions have become numerous and complex, often building on each other, the connections among these disparate cryptographic objects, and among their various security definitions, have become increasingly confusing. The goal of this work is to provide a clean and unifying framework for diverse cryptographic objects and their various security definitions, equipped with powerful 'reduction' and 'composition' theorems. We model the functionality desired from a cryptographic object via a 'schema' in an ideal world. Our new security definition, indistinguishability preservation, is parametrized by a family of 'test' functions. We say that a scheme securely implements a schema against a test family in the real world if for every test in the family, if test is able to hide some bit of information from all adversaries in the ideal world, then this bit should be hidden in the real world too. By choosing test families appropriately, we are able to place known security definitions (along with new ones) for a given object on the same canvas, enabling comparative analysis. Next, we explore the implications of a meaningful relaxation of our security definition, the one obtained by considering all-powerful adversaries in the ideal world. Thanks to our framework, we are not only able to substantially generalize known results connecting two important flavors of security definitions (simulation and indistinguishability) in cryptography under this relaxation, but significantly simplify them too. We also initiate a systematic study of the security of fundamental cryptographic primitives like public-key encryption under a new class of attacks that had not been considered so far in the literature. Once again, owing to the flexibility of our framework, we are able to model such attacks, along with existing ones, in a clean and satisfactory way

FORMULATION APPROACHES FOR SUSTAINED RELEASE DOSAGE FORMS: A REVIEW

Over the past 30 years, as the expense and complications involved in marketing new drug entities have increased, with concomitant recognition ofthe therapeutic advantages of controlled drug delivery, greater attention has been focused on development of sustained or controlled release drugdelivery systems (DDS). For many disease states, a substantial number of therapeutically effective compounds already exist. The effectiveness of thesedrugs is often limited by side effects or necessity to administer the compound in an ethical setting. The goal in designing sustained drug deliveryis to reduce the frequency of dosing or to increase the effectiveness of the drug by localization at the site of action, reducing the dose required orproviding uniform drug delivery. The design of oral sustained release DDS depends on various factors such as, physicochemical properties of drug,type of delivery system, disease being treated, and patient condition, and treatment duration, presence of food, gastrointestinal motility, and coadministrationof other drugs.Keywords: Sustained release drug delivery system, Dose frequency, Biological half-life, Physicochemical properties of drugs

Simplifying Design and Analysis of Complex Predicate Encryption Schemes

Wee (TCC\u2714) and Attrapadung (Eurocrypt\u2714) introduced predicate and pair encodings, respectively, as a simple way to construct and analyze attribute-based encryption schemes, or more generally predicate encryption. However, many schemes do not satisfy the simple information theoretic property proposed in those works, and thus require much more complicated analysis. In this paper, we propose a new simple property for pair encodings called symbolic security. Proofs that pair encodings satisfy this property are concise and easy to verify. We show that this property is inherently tied to the security of predicate encryption schemes by arguing that any scheme which is not trivially broken must satisfy it. Then we use this property to discuss several ways to convert between pair encodings to obtain encryption schemes with different properties like small ciphertexts or keys. Finally, we show that any pair encoding satisfying our new property can be used to construct a fully secure predicate encryption scheme. The resulting schemes are secure under a new q-type assumption which we show follows from several of the assumptions used to construct such schemes in previous work

FAME: Fast Attribute-based Message Encryption

Time and again, attribute-based encryption has been shown to be the natural cryptographic tool for building various types of conditional access systems with far-reaching applications, but the deployment of such systems has been very slow. A central issue is the lack of an encryption scheme that can operate on sensitive data very efficiently and, at the same time, provides features that are important in practice. This paper proposes the first fully secure ciphertext-policy and key-policy ABE schemes based on a standard assumption on Type-III pairing groups, which do not put any restriction on policy type or attributes. We implement our schemes along with several other prominent ones using the Charm library, and demonstrate that they perform better on almost all parameters of interest

Functional Encryption: Deterministic to Randomized Functions from Simple Assumptions

Functional encryption (FE) enables fine-grained control of sensitive data by allowing users to only compute certain functions for which they have a key. The vast majority of work in FE has focused on deterministic functions, but for several applications such as privacy-aware auditing, differentially-private data release, proxy re-encryption, and more, the functionality of interest is more naturally captured by a randomized function. Recently, Goyal et al. (TCC 2015) initiated a formal study of FE for randomized functionalities with security against malicious encrypters, and gave a selectively secure construction from indistinguishability obfuscation. To date, this is the only construction of FE for randomized functionalities in the public-key setting. This stands in stark contrast to FE for deterministic functions which has been realized from a variety of assumptions. Our key contribution in this work is a generic transformation that converts any general-purpose, public-key FE scheme for deterministic functionalities into one that supports randomized functionalities. Our transformation uses the underlying FE scheme in a black-box way and can be instantiated using very standard number-theoretic assumptions (for instance, the DDH and RSA assumptions suffice). When applied to existing FE constructions, we obtain several adaptively-secure, public-key functional encryption schemes for randomized functionalities with security against malicious encrypters from many different assumptions such as concrete assumptions on multilinear maps, indistinguishability obfuscation, and in the bounded-collusion setting, the existence of public-key encryption, together with standard number-theoretic assumptions. Additionally, we introduce a new, stronger definition for malicious security as the existing one falls short of capturing an important class of correlation attacks. In realizing this definition, our compiler combines ideas from disparate domains like related-key security for pseudorandom functions and deterministic encryption in a novel way. We believe that our techniques could be useful in expanding the scope of new variants of functional encryption (e.g., multi-input, hierarchical, and others) to support randomized functionalities

Secure Message Transmission In Asynchronous Directed Networks

We study the problem of information-theoretically secure message transmission (SMT) in asynchronous directed networks. In line with the literature, the distrust and failures of the network is captured via a computationally unbounded Byzantine adversary that may corrupt some subset of nodes. We give a characterization of networks over which SMT from sender S to receiver R is possible in both the well-known settings, namely perfect SMT (PSMT) and unconditional SMT (USMT). We distinguish between two variants of USMT: one in which R can output an incorrect message (with small probability) and another in which R never outputs a wrong message, but may choose to abort (with small probability). We also provide efficient protocols for an important class of networks

Unconditionally Reliable Message Transmission in Directed Neighbour Networks

The problem of unconditionally reliable message transmission (URMT) is to design a protocol which when run by players in a network enables a sender S to deliver a message to a receiver R with high probability, even when some players in the network are under the control of an unbounded adversary. Renault and Tomala [JoC2008] gave a characterization of undirected neighbour networks over which URMT tolerating Byzantine adversary is possible. In this paper, we generalize their result to the case of directed networks