讲座题目：Blackbox Traceable Attribute Based Encryption
时间： 2014年3月12日 9:00-11：00
讲座人： 王石博士 香港城市大学
Attribute-Based Encryption (ABE) is a promising technology for enabling fine-grained access control through encryption. In recent years, a series of expressive, secure and efficient ABE schemes, both in key-policy flavor and ciphertext-policy flavor, have been proposed. However, before being able to apply in practice, these systems have to support malicious user traceability, which is an important feature that a public key cryptosystem should possess in practical applications. As the decryption privilege of a decryption key in Key-Policy ABE (resp. Ciphertext-Policy ABE) may be shared by multiple users who own the same access policy (resp. attribute set), malicious users might tempt to leak their decryption privileges to third parties, for financial gain as an example. In this talk, we discuss about the traceability notion in the setting of ABE, and formalize Traceable ABE supporting fully collusion-resistant black-box traceability. An adversary is allowed to access an arbitrary number of keys of its own choice when building a decryption-device, and given such a decryption-device while the underlying decryption algorithm or key may not be given, a Black-Box tracing algorithm can find out at least one of the malicious users whose keys have been used for building the decryption-device. We describe how such a scheme can be built for supporting both fully collusion-resistant black-box traceability and high expressiveness (i.e. supporting any monotonic access structures). We will also show that an efficient scheme can be built, that will have the ciphertexts grow only sub-linearly in the number of system users.
Duncan S. Wong received his B.Eng. degree in Electrical & Electronic Engineering with first class honors from the University of Hong Kong in 1994, M.Phil. degree in Information Engineering from the Chinese University of Hong Kong in 1998 and Ph.D. degree in Computer Science from Northeastern University, Boston, MA, USA in 2002. He is now an Associate Professor in the Department of Computer Science at City University of Hong Kong. His primary research interest is applied cryptography; in particular, cryptographic protocols, encryption and signature schemes, and anonymous systems. He has authored over 150 publications in these areas. His publications have appeared in venues such as Asiacrypt, PKC, CT-RSA, FC and journals, such as IEEE Transactions on Information Theory, IEEE Transactions on Information Forensics and Security, Designs, Codes and Cryptography, and so on. Dr Wong was awarded the membership of Phi Beta Delta Honor Society for International Scholars and won the Outstanding Research Award at the College of Computer Science during his doctoral study. He has chaired three international conferences, served as an editor for two technical journals, and also served as a program committee member for over 50 international conferences including Eurocrypt and Asiacrypt.