Forward-Secure Public Key Encryption without Key Update from Proof-of-Stake Blockchain

A forward-secure public-key encryption (PKE) scheme prevents eavesdroppers from decrypting past ciphertexts in order to mitigate the damage caused by a potential secret key compromise. In prior works, forward security in a non-interactive setting, such as forward-secure PKE, is achieved by constantly updating (secret) keys. In this paper, we formalize the notion of blockchain-based forward-secure PKE and show the feasibility of constructing a forward-secure PKE scheme without key update (i.e. both the public key and the secret key are immutable), assuming the existence of a proof-of-stake blockchain with the distinguishable forking property introduced by Goyal, et al. (TCC 2017). Our construction uses the proof-of-stake blockchain as an immutable decryption log and witness encryption by Garg, et al. (STOC 2013) to ensure that the same ciphertext cannot be decrypted twice, thereby rendering a compromised secret key useless with respect to decryption of past ciphertext the legitimate user has already decrypted

Ultrafast All-Polymer Paper-Based Batteries

Conducting polymers for battery applications have been subject to numerous investigations during the last two decades. However, the functional charging rates and the cycling stabilities have so far been found to be insufficient for practical applications. These shortcomings can, at least partially, be explained by the fact that thick layers of the conducting polymers have been used to obtain sufficient capacities of the batteries. In the present letter, we introduce a novel nanostructured high-surface area electrode material for energy storage applications composed of cellulose fibers of algal origin individually coated with a 50 nm thin layer of polypyrrole. Our results show the hitherto highest reported charge capacities and charging rates for an all polymer paper-based battery. The composite conductive paper material is shown to have a specific surface area of 80 m2 g-1 and batteries based on this material can be charged with currents as high as 600 mA cm-2 with only 6 % loss in capacity over 100 subsequent charge and discharge cycles. The aqueous-based batteries, which are entirely based on cellulose and polypyrrole and exhibit charge capacities between 25 and 33 mAh g-1 or 38-50 mAh g-1 per weight of the active material, open up new possibilities for the production of environmentally friendly, cost efficient, up-scalable and lightweight energy storage systems. There is currently a great interest in the development of thin, flexible, lightweight, and environmentally friendly batteries and supercapacitors.1 In this process, the preparation of novel redox polymer and electronically conducting polymer-base

Synthesis of air‐stable, odorless thiophenol surrogates via Ni‐Catalyzed C−S cross‐coupling

Thiophenols are versatile synthetic intermediates whose practical appeal is marred by their air sensitivity, toxicity and extreme malodor. Herein we report an efficient catalytic method for the preparation of S-aryl isothiouronium salts, and demonstrate that these air-stable, odorless solids serve as user-friendly sources of thiophenols in synthesis. Diverse isothiouronium salts featuring synthetically useful functionality are readily accessible via nickelcatalyzed C-S cross-coupling of (hetero)aryl iodides and thiourea. Convenient, chromatography-free isolation of these salts is achieved via precipitation, allowing the methodology to be translated directly to large scales. Thiophenols are liberated from the corresponding isothiouronium salts upon treatment with a weak base, enabling an in situ release / S-functionalization strategy that entirely negates the need to isolate, purify or manipulate these noxious reagent

Ciphertext-Policy Attribute Based Encryption Supporting Access Policy Update

Attribute-based encryption (ABE) allows one-to-many encryption with static access control. In many occasions, the access control policy must be updated and the original encryptor might be required to re-encrypt the message, which is impractical, since the encryptor might be unavailable. Unfortunately, to date the work in ABE does not consider this issue yet, and hence this hinders the adoption of ABE in practice. In this work, we consider how to efficiently update access policies in Ciphertext-policy Attribute-based Encryption (CP-ABE) systems without re-encryption. We introduce a new notion of CP-ABE supporting access policy update that captures the functionalities of attribute addition and revocation to access policies. We formalize the security requirements for this notion, and subsequently construct two provably secure CP-ABE schemes supporting AND-gate access policy with constant-size ciphertext for user decryption. The security of our schemes are proved under the Augmented Multi-sequences of Exponents Decisional Diffie-Hellman assumption

Common Variants in the COL4A4 Gene Confer Susceptibility to Lattice Degeneration of the Retina

Lattice degeneration of the retina is a vitreoretinal disorder characterized by a visible fundus lesion predisposing the patient to retinal tears and detachment. The etiology of this degeneration is still uncertain, but it is likely that both genetic and environmental factors play important roles in its development. To identify genetic susceptibility regions for lattice degeneration of the retina, we performed a genome-wide association study (GWAS) using a dense panel of 23,465 microsatellite markers covering the entire human genome. This GWAS in a Japanese cohort (294 patients with lattice degeneration and 294 controls) led to the identification of one microsatellite locus, D2S0276i, in the collagen type IV alpha 4 (COL4A4) gene on chromosome 2q36.3. To validate the significance of this observation, we evaluated the D2S0276i region in the GWAS cohort and in an independent Japanese cohort (280 patients and 314 controls) using D2S0276i and 47 single nucleotide polymorphisms covering the region. The strong associations were observed in D2S0276i and rs7558081 in the COL4A4 gene (Pc = 5.8×10−6, OR = 0.63 and Pc = 1.0×10−5, OR = 0.69 in a total of 574 patients and 608 controls, respectively). Our findings suggest that variants in the COL4A4 gene may contribute to the development of lattice degeneration of the retina