This paper proposes a new UGC-oriented language technology application, which we call experience mining. Experience mining aims at automatically collecting instances of personal experiences as well as opinions from an explosive number of user generated contents (UGCs) such as weblog and forum posts and storing them in an experience database with semantically rich indices. After arguing the technical issues of this new task, we focus on the central problem, factuality analysis, among others and propose a machine learning-based solution as well as the task definition itself. Our empirical evaluation indicates that our factuality analysis task is sufficiently well-defined to achieve a high inter-annotator agreement and our Factorial CRF-based model considerably outperforms the baseline. We also present an application system, which currently stores over 50M experience instances extracted from 150M Japanese blog posts with semantic indices and is scheduled to start serving as an experience search engine for unrestricted users in October.

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In the ordinary security model for signature schemes, we consider an adversary that may forge a signature on a new message using only his knowledge of other valid message and signature pairs. To take into account side channel attacks such as tampering or fault-injection attacks, Bellare and Kohno (Eurocrypt 2003) formalized related-key attacks (RKA), where stronger adversaries are considered. In RKA for signature schemes, the adversary can also manipulate the signing key and obtain signatures for the modified key. This paper considers RKA security of two established signature schemes: the Schnorr signature scheme and (a well-known variant of) DSA. First, we show that these signature schemes are secure against a weak notion of RKA. Second, we demonstrate that, on the other hand, neither the Schnorr signature scheme nor DSA achieves the standard notion of RKA security, by showing concrete attacks on these. Lastly, we show that a slight modification of both the Schnorr signature scheme and (the considered variant of) DSA yields fully RKA secure schemes.

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