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Wang C.,Sun Yat Sen University | Wang C.,Guangdong Province Information Security Key Laboratory | Wang C.,South China Normal University | Luo J.,Sun Yat Sen University | Luo J.,Guangdong Province Information Security Key Laboratory
Mathematical Problems in Engineering | Year: 2013

There is an acceleration of adoption of cloud computing among enterprises. However, moving the infrastructure and sensitive data from trusted domain of the data owner to public cloud will pose severe security and privacy risks. Attribute-based encryption (ABE) is a new cryptographic primitive which provides a promising tool for addressing the problem of secure and fine-grained data sharing and decentralized access control. Key-policy attribute-based encryption (KP-ABE) is an important type of ABE, which enables senders to encrypt messages under a set of attributes and private keys are associated with access structures that specify which ciphertexts the key holder will be allowed to decrypt. In most existing KP-ABE scheme, the ciphertext size grows linearly with the number of attributes embedded in ciphertext. In this paper, we propose a new KP-ABE construction with constant ciphertext size. In our construction, the access policy can be expressed as any monotone access structure. Meanwhile, the ciphertext size is independent of the number of ciphertext attributes, and the number of bilinear pairing evaluations is reduced to a constant. We prove that our scheme is semantically secure in the selective-set model based on the general Diffie-Hellman exponent assumption. © 2013 Changji Wang and Jianfa Luo. Source


Wang C.-J.,Sun Yat Sen University | Wang C.-J.,Guangdong Province Information Security Key Laboratory | Wang C.-J.,South China Normal University | Huang J.-S.,Sun Yat Sen University | And 5 more authors.
Proceedings - 5th International Conference on Intelligent Networking and Collaborative Systems, INCoS 2013 | Year: 2013

In SCN2010, Gagné, Narayan, and Safavi-Naini proposed attribute-based signcryption with threshold structure. As in cipher text-policy attribute-based encryption, a sender can specify the access structure of recipients, and as in attribute-based signature, each recipient can verify the sender's attributes. In contrast to the access structure of recipients, the access structure of the sender needs to be fixed in the setup phase. In this paper, we show that Gagné et al.'s threshold attribute-based signcryption is not secure and give a concrete forgery attack. The attack can make use some keys to construct any other legal keys and at last totally break the scheme. We also show that the attack is effective on other attribute-based cryptographic schemes with the same key structure. © 2013 IEEE. Source


Wang C.-J.,Sun Yat Sen University | Wang C.-J.,Guangdong Province Information Security Key Laboratory | Wang C.-J.,South China Normal University | Lin W.-L.,Sun Yat Sen University | And 3 more authors.
Proceedings - 4th International Conference on Emerging Intelligent Data and Web Technologies, EIDWT 2013 | Year: 2013

The rapid development of instant messaging changes the people's communication, collaboration and entertainment manner radically. Unfortunately, the existing instant messaging technology does not provide built-in support for security features. The security problem of instant messaging system has aroused widespread concern in both academia and industry. In this paper, we proposed a new and secure instant messaging system by using identity-based cryptosystems, which can provide strong authentication and secure communication (confidentiality, integrity and non-repudiation) for both instant messaging client to instant messaging server and instant messaging client to instant messaging client. The proposed instant messaging system is simpler and more efficient than those of existing instant messaging systems. © 2013 IEEE. Source


Wang C.-J.,Sun Yat Sen University | Wang C.-J.,Guangdong Province Information Security Key Laboratory | Wang C.-J.,South China Normal University | Li Y.,Sun Yat Sen University | And 3 more authors.
Proceedings - 4th International Conference on Emerging Intelligent Data and Web Technologies, EIDWT 2013 | Year: 2013

Since Mambo et al. introduced the concept of proxy signature in 1996, many proxy signature schemes have been proposed. Recently, Wang et al. and Zhao et al. proposed an ID-based proxy signature scheme and an ID-based anonymous proxy signature scheme, respectively. And they also claimed that the proposed scheme satisfied the required security properties of proxy signature. In this paper, we show that these two proxy signature schemes are insecure against original signer's forgery, and can not provide undeniability. © 2013 IEEE. Source


Wang C.,Sun Yat Sen University | Wang C.,Guangdong Province Information Security Key Laboratory | Wang C.,South China Normal University | Liu X.,Sun Yat Sen University | And 3 more authors.
International Journal of Intelligent Information and Database Systems | Year: 2013

There is an acceleration of adoption of cloud computing among healthcare enterprises. In this paper, we design and develop a patient-centric, cloud-based personal health record system based on open-source Indivo project. The developed cloud-based personal health record (PHR) system enables patients to securely store and share their personal health records in a flexible way by using ciphertext-policy attribute-based encryption mechanism. Copyright © 2013 Inderscience Enterprises Ltd. Source

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