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The scalable video coding extension of H.264/AVC standard specifies the usage of layered scalable bit streams to achieve temporal, spatial and quality scalability. The inter-layer redundancies are exploited in addition to spatial and temporal predictions to obtain a better coding efficiency. The addition of inter-layer modes increases the computational complexity of the mode decision process in the enhancement layer. We propose a fast mode decision algorithm based on spatiograms for reducing the computational overhead during the encoding process. Our algorithm is based on constructing spatiograms for the macroblocks and comparing them to find the similarity of the macroblocks. This similarity measure is used to evaluate only a subset of modes leading to reduction in coding time. Our experiment results show that the time saving is around 29% to 67% based on the video sequence with a quality loss between 0 to -0.04dB and bit rate increase in the range -0.21% to 0.94%. The quality loss and the bit rate increase from our proposed algorithm is extremely insignificant when compared to the original JSVM 9.8 reference implementation. [ABSTRACT FROM AUTHOR]

Certificateless cryptography introduced by Al-Riyami and Paterson eliminates the key escrow problem inherent in identity based cryptosystems. Even though building practical identity based signcryption schemes without bilinear pairing are considered to be almost impossible, it will be interesting to explore possibilities of constructing such systems in other settings like certificateless cryptography. Often for practical systems, bilinear pairings are considered to induce computational overhead. Signcryption is a powerful primitive that offers both confidentiality and authenticity to noteworthy messages. Though some prior attempts were made for designing certificateless signcryption schemes, almost all the known ones have security weaknesses. Specifically, in this paper we demonstrate the security weakness of the schemes in [2], [1] and [6]. We also present the first provably secure certificateless signcryption scheme without bilinear pairing and prove it in the random oracle model. [ABSTRACT FROM AUTHOR]

Sanitizable signatures provide several security features which are useful in many scenarios including military and medical applications. Sanitizable signatures allow a semi-trusted party to update some part of the digitally signed document without interacting with the original signer. Such schemes, where the verifier cannot identify whether the message has been sanitized, are said to possess strong transparency. In this paper, we have described the first efficient and provably secure sanitizable signature scheme having strong transparency under the standard model. [ABSTRACT FROM AUTHOR]

Signcryption is a cryptographic primitive that fulfills both the functions of digital signature and public key encryption in a single step, at a cost significantly lower than that is required by the traditional signature-then-encrypt approach. Threshold involved with signcryption is used where the sender or receiver side has a group of members. Threshold Signcryption comes into picture when a message to be sent needs the authentication of a particular number of members in an organization, whereas threshold unsigncryption is used where until a given number of members join, a particular message cannot be decrypted. In this paper we show that three of the threshold signcryption schemes reported in the literature, lack confidentiality under the stronger notion of insider security. We also propose an improved scheme and give the formal proof of security in new stronger security model. [ABSTRACT FROM AUTHOR]

We propose an efficient statistically secure asynchronous multiparty computation (AMPC) protocol with optimal fault tolerance; i.e., with n = 3t + 1, where n is the total number of parties and t is the number of parties that can be under the influence of a Byzantine (active) adversary ]> having unbounded computing power. Our protocol privately communicates ]> bits per multiplication gate and involves a negligible error probability of 2 − Ώ(Κ), where Κ is the error parameter. As far as our knowledge is concerned, the only known statistically secure AMPC protocol with n = 3t + 1 is due to [7], which privately communicates Ώ(n11Κ4) bits and A-casts Ώ(n11Κ2 log(n)) bits per multiplication gate. Here A-cast is an asynchronous broadcast primitive, which allows a party to send some information to all other parties identically. Thus our AMPC protocol shows significant improvement in communication complexity over the AMPC protocol of [7]. [ABSTRACT FROM AUTHOR]

Integrating data mining techniques into database systems has gained popularity and its significance is well recognized. However, the performance of SQL based data mining is known to fall behind specialized implementations. Reasons for this are among others the prohibitive nature of the cost associated with extracting knowledge as well as the lack of suitable declarative query language support. Recent studies have found that for association rule mining and sequential pattern mining with carefully tuned SQL formulations it is possible to achieve performance comparable to systems that cache the data in files outside the DBMS. However, most of the previous pattern mining methods follow the method of Apriori, which still encounters problems when a sequential database is large and/or when sequential patterns to be mined are numerous and long. In this paper, we present a novel SQL based approach that we recently proposed, called Prospad (PROjection Sequential PAttern Discovery). Prospad fundamentally differs from an Apriori-like candidate set generation-and-test approach. This approach is a pattern growth-based approach without candidate generation. It grows longer patterns from shorter ones by successively projecting the sequential table into subsequential tables. Since a projected table for a sequential pattern i contains all and only necessary information for mining the sequential patterns that can grow from i, the size of the projected table usually reduces quickly as mining proceeds to longer patterns. Moreover, a depth first approach is used to facilitate the projecting process in order to avoid creating and dropping costs of temporary tables. [ABSTRACT FROM AUTHOR]