Adaptively secure lattice-based revocable IBE in the QROM: compact parameters,tight security,and anonymity

Designs, Codes and Cryptography - Revocable identity-based encryption (RIBE) is an extension of IBE that satisfies a key revocation mechanism to manage a number of users dynamically and...     

一类Z2k-线性的二元码

我们记Tk为Galois环GR（2^k,m)到Z2^k的迹映射，ξ是GR（2^k,m)中的本原元，ξ2^m-1=1,ιk,m={0,1,ξ，…，ξ2^m-2}，来讨论一类Z2^k-线性码{Tk(a0x 2^k-2a1x^3 2^k-1,a2x^5) b|a0∈GR(2^k,m),a1∈ιk,m 2ιk,m,a2∈ιk,m,b∈Z2^k}x∈ιk的广义Gray映射下的象所构成的二元码，这类二元码也具有很好的参数性质，优于一些已知的二元码，例如广义的Kerdock码或广义的Delsarte-Goethals码。     

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’s 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 and SE all consist of only a constant number of group elements.     

Obtaining a secure and efficient key agreement protocol from (H)MQV and NAXOS

LaMacchia, Lauter and Mityagin recently presented a strong security definition for authenticated key agreement strengthening the well-known Canetti-Krawczyk definition. They also described a protocol, called NAXOS, that enjoys a simple security proof in the new model. Compared to MQV and HMQV, NAXOS is less efficient and cannot be readily modified to obtain a one-pass protocol. On the other hand MQV does not have a security proof, and the HMQV security proof is extremely complicated. This paper proposes a new authenticated key agreement protocol, called CMQV (‘Combined’ MQV), which incorporates design principles from MQV, HMQV and NAXOS. The new protocol achieves the efficiency of HMQV and admits a natural one-pass variant. Moreover, we present a relatively simple and intuitive proof that CMQV is secure in the LaMacchia-Lauter-Mityagin model.      

A comparison study of extreme precipitation from six different regional climate models via spatial hierarchical modeling

We analyze output from six regional climate models (RCMs) via a spatial Bayesian hierarchical model. The primary advantage of this approach is that the statistical model naturally borrows strength across locations via a spatial model on the parameters of the generalized extreme value distribution. This is especially important in this application as the RCM output we analyze have extensive spatial coverage, but have a relatively short temporal record for characterizing extreme behavior. The hierarchical model we employ is also designed to be computationally efficient as we analyze RCM output for nearly 12000 locations. The aim of this analysis is to compare the extreme precipitation as generated by these RCMs. Our results show that, although the RCMs produce similar spatial patterns for the 100-year return level, their characterizations of extreme precipitation are quite different. Additionally, we examine the spatial behavior of the extreme value index and find differing spatial patterns for the point estimates for the RCMs. However, these differences may not be significant given the uncertainty associated with estimating this parameter.     

An efficiency estimate for a hierarchical reconstruction method in the problem of reconstructing the locations of discrete scattering centers from a set of projections

Under consideration is the problem of determining a maximal set for a family of points from a restricted collection of their two-dimensional projections. This problem arises naturally in the applications of physical hydroaerodynamics to optical diagnostics of real liquid and gas flows by measuring the instantaneous velocity fields in a flow volume. We propose some methods for reconstructing the original set and determining the sufficiency of measurement for solving uniquely the inverse problem for parallel and perspective projections. We statistically evaluate the efficiency of the reconstruction method.