Short Signatures from the Weil Pairing
ASIACRYPT '01 Proceedings of the 7th International Conference on the Theory and Application of Cryptology and Information Security: Advances in Cryptology
Improved proxy re-encryption schemes with applications to secure distributed storage
ACM Transactions on Information and System Security (TISSEC)
Chosen-Ciphertext Secure Proxy Re-encryption without Pairings
CANS '08 Proceedings of the 7th International Conference on Cryptology and Network Security
Conditional Proxy Broadcast Re-Encryption
ACISP '09 Proceedings of the 14th Australasian Conference on Information Security and Privacy
Data Security in the World of Cloud Computing
IEEE Security and Privacy
Efficient Conditional Proxy Re-encryption with Chosen-Ciphertext Security
ISC '09 Proceedings of the 12th International Conference on Information Security
Secure provenance: the essential of bread and butter of data forensics in cloud computing
ASIACCS '10 Proceedings of the 5th ACM Symposium on Information, Computer and Communications Security
The twin Diffie-Hellman problem and applications
EUROCRYPT'08 Proceedings of the theory and applications of cryptographic techniques 27th annual international conference on Advances in cryptology
Achieving secure, scalable, and fine-grained data access control in cloud computing
INFOCOM'10 Proceedings of the 29th conference on Information communications
Establishing Trust in Cloud Computing
IT Professional
Security and Privacy Challenges in Cloud Computing Environments
IEEE Security and Privacy
Security Challenges for the Public Cloud
IEEE Internet Computing
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Over years, cloud computing has been rapidly changing the shape of modern computing environment. The problem of how to keep the confidentiality of user data against malicious entities including a cloud service provider has been recognized as a significant issue. This problem becomes even more complicated if a data is shared among multiple users. Recently, the idea of proxy re-encryption has been introduced to support secure data sharing among group members in cloud environment. However, in this scheme, a malicious user can collude with the server to decrypt unauthorized messages. The conditional proxy re-encryption (CPRE) aims to fix this problem by introducing a condition value into message encryption process and re-encryption key generation. We observe that CPRE becomes significantly inefficient when the membership of the group changes very actively and the size of the group is large since a new condition value is selected and re-encryption keys have to be generated for each user whenever the group membership is changed. This paper introduces a new CPRE in which the condition value is not associated with re-encryption keys. Whenever a group membership is changed, only a new condition value is distributed to the users via cloud server. As a result, the overhead of each user becomes significantly reduced at each membership change.