Leakage-Resilient Lattice-Based Partially Blind Signatures

Blind signature schemes (BSS) play a pivotal role in privacy-oriented cryptography. However, with blind signature schemes, the signed message remains unintelligible to the signer, giving them no guarantee that the blinded message he signed actually contained valid information. Partially-blind signature schemes (PBSS) were introduced to address precisely this problem. In this paper we present the first leakage-resilient, lattice-based partially-blind signature scheme in the literature. Our construction is provably secure in the random oracle model (ROM) and offers quasilinear complexity w.r.t. key/signature sizes and signing speed. In addition, it offers statistical partial blindness and its unforgeability is based on the computational hardness of worst-case ideal lattice problems for approximation factors in $˜ O(n^4)$ in dimension $n$. Our scheme benefits from the subexponential hardness of ideal lattice problems and remains secure even if a (1-o(1)) fraction of the signer’s secret key leaks to an adversary via arbitrary side-channels. Several extensions of the security model, such as honest-user unforgeability and selective failure blindness, are also considered and concrete parameters for instantiation are proposed

On a stationary spinning string spacetime

The properties of a stationary massless string endowed with intrinsic spin are discussed. The spacetime is Minkowskian geometrically but the topology is nontrivial due to the horizon located on the surface $r=0$, similar with Rindler's case. For $r$ less than the Planck length $b$, $g_{\phi\phi}$ has the same sign as $g_{tt}$ and closed timelike curves are possible. We assume an elementary particles' spin originates in the frame dragging effect produced by the rotation of the source. The Sagnac time delay is calculated and proves to be constant.Comment: revised version of hep-th/0602014 v1, 7 pages, title changed, sec.5 removed, talk given at "Recent Developments in Gravity" (NEB XII), Nafplio, Greece, 29 June 200

Evidence for Nonlinear Asymmetric Causality in US Inflation, Metal, and Stock Returns

The purpose of this paper is to propose a version of causality testing that focuses on how the sign of the returns affects the causality results. We replace the traditional VAR specification used in the Granger causality test by a discrete-time bivariate noisy Mackey glass model. Our test reveals interesting and previously unexplored relationships in US economic series, including inflation, metal, and stock returns

Research Article Evidence for Nonlinear Asymmetric Causality in US Inflation, Metal, and Stock Returns

purpose of this paper is to propose a version of causality testing that focuses on how the sign of the returns affects the causality results. We replace the traditional VAR specification used in the Granger causality test by a discrete-time bivariate noisy Mackey glass model. Our test reveals interesting and previously unexplored relationships in US economic series, including inflation, metal, and stock returns. Copyright q 2008 D. Hristu-Varsakelis and C. Kyrtsou. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1