CAPTCHAs/HIPs are security mechanisms that try to prevent automatic abuse of services. They are susceptible to learning attacks in which attackers can use them as oracles. Kwon and Cha presented recently a novel algorithm that intends to avoid such learning attacks and “detect all bots” [6]. They add uncertainties to the grading of challenges, and also use trap images designed to detect bots. T...

Oracle Spatial and Graph – RDF Semantic Graph, an option for Oracle Database 12c, is the only mainstream commercial RDF triplestore that supports the OGC GeoSPARQL standard for spatial data on the Semantic Web. This demonstration will give an overview of the GeoSPARQL implementation in Oracle Spatial and Graph and will show how to load, index and query spatial RDF data. In addition, this demons...

Oracle complexity of the problem under the oracle based optimization model introduced by Nemirovski & Yudin (1978) is considered. We show that the oracle complexity can be lower bounded by fat-shattering dimension introduced by Kearns & Schapire (1990), a key tool in learning theory. Using this result, we proceed to establish upper bounds on learning rates for agnostic PAC learning with linear ...

We give the first proof of security for an identity-based encryption scheme in the quantum random oracle model. This is the first proof of security for any scheme in this model that requires no additional assumptions. Our techniques are quite general and we use them to obtain security proofs for two random oracle hierarchical identity-based encryption schemes and a random oracle signature schem...