Fast, Compact, and Expressive Attribute-Based Encryption

Attribute-based encryption (ABE) is an advanced cryptographic tool and useful to build various types of access control systems. Toward the goal of making ABE more practical, we propose key-policy (KP) and ciphertext-policy (CP) ABE schemes, which first support unbounded sizes of attribute sets and policies with negation and multi-use of attributes, allow fast decryption, and are fully secure under a standard assumption, simultaneously. The proposed schemes are more expressive than previous schemes and efficient enough. We also implement our schemes in 128-bit security level and present their benchmarks for an ordinary personal computer and smartphones. They show that all algorithms run in one second with the personal computer when they handle any policy or attribute set with one hundred attributes

Naturally Occurring 3RS, 7R, 11R-Phytanic Acid Suppresses In Vitro T-Cell Production of Interferon-Gamma

Background: Among the eight stereoisomers of phytanic acid (PA), the 3RS, 7R, 11R-isomer is naturally occurring and is present in foods and the human body. PA is considered to have possible health benefits in the immune system. However, it remains undetermined whether these effects are elicited by the 3RS, 7R, 11R-PA isomer, because previous studies used a commercially available PA whose isomer configuration is unknown. In this study, we synthesized a preparation of 3RS, 7R, 11R-PA, and investigated its in vitro immunomodulatory effects, especially the T-cell production of interferon (IFN)-γ, which is associated with various autoimmune diseases. This study also investigated the effects of 3RS, 7R, 11R-PA on NF-κB activity in order to address the mechanism of its immunomodulatory effects. Methods: Mouse splenocytes and purified T-cells were stimulated with T-cell mitogens and incubated with 3RS, 7R, 11R-PA, followed by evaluation of IFN-γ production. The effect of 3RS, 7R, 11R-PA on NF-κB activity was also investigated using an A549 cell line with stable expression of an NF-κB-dependent luciferase reporter gene. Results: 3RS, 7R, 11R-PA significantly reduced in vitro IFN-γ production at both the protein and mRNA levels, and was accompanied by decreased expression of T-bet, a key regulator of Th1 cell differentiation. The results indicated that NFκB-mediated transcriptional activity was significantly decreased by 3RS, 7R, 11R-PA and that GW6471, an antagonist of peroxisome proliferator activated receptor α (PPARα), abrogated the inhibitory effect of 3RS, 7R, 11R-PA on NF-κB activity. Conclusions: The present study suggests that 3RS, 7R, 11R-PA is a functional and bioactive fatty acid, and has a potentially beneficial effect for amelioration of T-cell mediated autoimmune diseases. This study also indicates that interference in the NF-κB pathway via PPARα activation is a potential mechanism of the immunomodulatory effects of 3RS, 7R, 11R-PA

Multi-Cast Key Distribution: Scalable, Dynamic and Provably Secure Construction

In this paper, we propose a two-round dynamic multi-cast key distribution (DMKD) protocol under the star topology with a central authentication server. Users can share a common session key without revealing any information of the session key to the server, and can join/leave to/from the group at any time even after establishing the session key. Our protocol is scalable because communication and computation costs of each user are independent from the number of users. Also, our protocol is still secure if either private key or session-specific randomness of a user is exposed. Furthermore, time-based backward secrecy is guaranteed by renewing the session key for every time period even if the session key is exposed. We introduce the first formal security definition for DMKD under the star topology in order to capture such strong exposure resilience and time-based backward secrecy. We prove that our protocol is secure in our security model in the standard model

Potential therapeutic applications of targeting signal-transducing adaptor protein-2 in autoimmune diseases

Adaptor proteins are involved in various immune responses via the modulation of many signaling pathways. Signal-transducing adaptor protein-2 (STAP-2) is an adaptor protein that contains typical domains such as the pleckstrin homology (PH) domain, Src homology domain, and a proline-rich region from the N-terminal region. In T cells, STAP-2 positively regulates T cell receptor (TCR)-mediated signaling by associating with CD3ζ immunoreceptor tyrosine-based activation motifs (ITAMs) and lymphocyte-specific protein tyrosine kinase (LCK). Therefore, a peptide that inhibits the interaction between STAP-2 and CD3ζ ITAMs is likely to suppress TCR-mediated T cell activation, as well as T cell-mediated diseases. As expected, the peptide successfully inhibited the STAP-2/CD3ζ ITAM interaction and suppressed TCR-mediated signaling, cell proliferation, and interleukin (IL)-2 production in human/murine T cells. Furthermore, this inhibitor suppressed the pathogenesis of experimental autoimmune encephalomyelitis (EAE), which is widely recognized as a mouse model of multiple sclerosis, via the downregulation of T cell activation and infiltration of T helper (Th) 1/Th17 cells. These results suggest a new strategy for the treatment of multiple sclerosis and other immune diseases

On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective

Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher δ18O, Δ17O, and ε54Cr values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10’s of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation

A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss

Efficient Implementation of Tate Pairing on a Mobile Phone using Java

Pairing-based cryptosystems (PBC) have been attracted by researchers in cryptography. Some implementations show that PBC are relatively slower than the standard public key cryptosystems. We present an efficient implementation for computing Tate pairing on a mobile phone using Java. We implemented the $\eta_T$ pairing (a recent efficient variation of Duursma-Lee algorithm) over some finite fields of characteristic 3 with extension degree $m= \{ 97, 167, 193, 239 \}$. Our optimized implementation for $m=97$ achieved about 0.5 seconds for computing Tate pairing over FOMA SH901iS, NTT DoCoMo. Then our implementation of Tate pairing is compared in the same platform with other Java program of the standard cryptosystems, i.e., RSA cryptosystem and elliptic curve cryptosystem (ECC). The computation speed of Tate pairing is comparable to that of RSA or ECC on the same mobile device

標数3の超特異楕円曲線上のηTペアリングの高速実装

Abstract / Acknowledgements / List of Tables / List of Algorithms / 1 Introduction / 2 Mathematical Background / 3 ηT Pairing over F_3m / 4 The Detail of Implementation of ηT Pairing over F_3m / 5 Construction of Addition and Subtraction in F_3 using Minimum Number of Logical Instructions / 6 MapToPoint over Supersingular Elliptic Curves in F_3m / 7 Experiment and Timing Results / 8 Conclusion / Bibliography / HistoryMade available in DSpace on 2012-04-18T01:10:31Z (GMT). No. of bitstreams: 2 math149.pdf: 412991 bytes, checksum: ceef9c914b485e00995a9ef91ebc9ceb (MD5) math149_abstract.pdf: 162468 bytes, checksum: eca64bb0ccf2f7d8b0621e292c24130e (MD5)Submitted by 真弓 小柳 ([email protected]) on 2012-04-18T01:10:31Z No. of bitstreams: 2 math149.pdf: 412991 bytes, checksum: ceef9c914b485e00995a9ef91ebc9ceb (MD5) math149_abstract.pdf: 162468 bytes, checksum: eca64bb0ccf2f7d8b0621e292c24130e (MD5)主1数理Pairing-based cryptosystems can provide cryptographic schemes which have novel and useful properties, such as Identity-based encryption schemes, and they have been attracted in cryptography. These schemes are constructed by using pairings, such as the Tate and Weil pairings, hash functions, and group computations. Miller proposed the first polynomial-time algorithm for computing the Weil pairing on algebraic curves, and various pairings are indicated until now. ηT pairing over F_3m is one of the fastest pairings now