Security Analysis of Some Proxy Signature

A proxy signature scheme allows an entity to delegate his/her signing capability to another entity in such a way that the latter can sign messages on behalf of the former. Such schemes have been suggested for use in a number of applications, particularly in distributed computing where delegation of rights is quite common. Followed by the rst schemes introduced by Mambo, Usuda and Okamoto in 1996, a number of new schemes and improvements have been proposed. In this paper, we present a security analysis of four such schemes newly proposed in [15, 16]. By successfully identifying several interesting forgery attacks, we show that all the four schemes are insecure. Consequently, the fully distributed proxy scheme in [11] is also insecure since it is based on the (insecure) LKK scheme [14, 15]. In addition, we point out the reasons why the security proofs provided in [15] are invalid

Painting Scene Recognition Using Homogenous Shapes

Abstract. This paper addresses the problem of semantic analysis of paintings by automatic detection of the represented scene type. The so-lution comes as an incipient effort to fill the gap already stated in the literature between the low level computational analysis and the high level semantic dependent human analysis of paintings. Inspired by the way humans perceive art, we first decompose the image in homogenous regions, follow by a step of region merging, in order to obtain a painting description by the extraction of perceptual features of the dominant ob-jects within the scene. These features are used in a classification process that discriminates among 5 possible scene types on a database of 500 paintings

Towards Network Denial Of Service Resistant Protocols

Networked and distributed systems have introduced a new significant threat to the availability of data and services: network denial of service attacks. A well known example is the TCP SYN ooding. In general, any statefull handshake protocol is vulnerable to similar attacks. This paper examines the network denial of service in detail and surveys and compares different approaches towards preventing the attacks. As a conclusion, a number of protocol design principles are identified essential in designing network denial of service resistant protocols, and examples provided on applying the principles

Proceedings of the 2005 International Conference on Grid Computing and Applications, GCA'05: Foreword

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