Attribute-Based Encryption Without Key Escrow
Attribute-Based Encryption (ABE) is a promising cryptographic primitive for fine-grained sharing of encrypted data. However, ABE has a major shortcoming which is called the key escrow problem. Key generation center (KGC) can generate the secret key of a user with arbitrary set of attributes. Even worse, KGC can decrypt ciphertext directly using its master key. This could be a potential intimidation to data security and privacy. In this paper, we propose a novel ciphertext-policy ABE scheme without key escrow. In our construction, we use two authorities, KGC and OAA (outsourced attribute authority). Unless KGC colludes with OAA, neither KGC nor OAA can decrypt the ciphertext independently. Our scheme is proved to be selectively secure in the standard model. We give universal methods for transforming both KP-ABE and CP-ABE with a single authority to solve the problem of key escrow. Our scheme naturally supports outsourcing the decryption of ciphertexts.
KeywordsCloud storage Access control Attribute-based encryption Key escrow Outsourcing decryption
This work is supported by the National High Technology Research and Development Program (“863” Program) of China under Grant No. 2015AA016009, the National Natural Science Foundation of China under Grant No. 61232005, and the Science and Technology Program of Shen Zhen, China under Grant No. JSGG2014051 6162852628.
- 3.Goyal, V., Pandey, O., Sahai, A., Waters, B.: Attribute-based encryption for fine-grained access control of encrypted data. In: ACM Conference on Computer and Communications Security, pp. 89–98 (2006)Google Scholar
- 4.Ostrovsky, R., Sahai, A., Waters, B.: Attribute-based encryption with non-monotonic access structures. In: ACM Conference on Computer and Communications Security, pp. 195–203 (2007)Google Scholar
- 6.Rouselakis, Y., Waters, B.: Practical constructions and new proof methods for large universe attribute-based encryption. In: ACM Conference on Computer and Communications Security, pp. 463–474 (2013)Google Scholar
- 7.Bethencourt, J., Sahai, A., Waters, B.: Ciphertext-policy attribute-based encryption. In: IEEE Symposium on Security and Privacy, pp. 321–334 (2007)Google Scholar
- 8.Cheung, L., Newport, C.: Provably secure ciphertext policy ABE. In: ACM Conference on Computer and Communications Security, pp. 456–465 (2007)Google Scholar
- 12.Zhang, G., Liu, L., Liu, Y.: An attribute-based encryption scheme secure against malicious KGC. In: IEEE 11th International Conference on Trust, Security and Privacy in Computing and Communications (TrustCom), pp. 1376–1380 (2012)Google Scholar
- 15.Green, M., Hohenberger, S., Waters, B.: Outsourcing the decryption of ABE ciphertexts. In: USENIX Security Symposium (2011)Google Scholar
- 16.Beimel, A.: Secure schemes for secret sharing and key distribution. PhD thesis, Israel Institute of Technology, Technion, Haifa, Israel (1996)Google Scholar
- 18.Chase, M., Chow, S.S.: Improving privacy and security in multi-authority attribute-based encryption. In: ACM Conference on Computer and Communications Security, pp. 121–130 (2009)Google Scholar
- 21.Wang, G., Liu, Q., Wu, J.: Hierarchical attribute-based encryption for fine-grained access control in cloud storage services. In: Proceedings of the 17th ACM Conference on Computer and Communications Security, pp. 735–737 (2010)Google Scholar