CryptoCache: a secure sharable file cache for roaming users

ABSTRACT

Small mobile computers are now sufficiently powerful to run many applications, but storage capacity remains limited so working files cannot be cached or stored locally. Even if files can be stored locally, the mobile device is not powerful enough to act as server in collaborations with other users. Conventional distributed file systems cache everything locally or not at all; there is no possibility to cache files on nearby nodes.In this paper we present the design of a secure cache system called CryptoCache that allows roaming users to cache files on untrusted file hosting servers. The system allows flexible sharing of cached files among unauthenticated users, i.e. unlike most distributed file systems CryptoCache does not require a global authentication framework.Files are encrypted when they are transferred over the network and while stored on untrusted servers. The system uses public key cryptography, which allows roaming users to selectively grant read and write access to others by entrusting them with respectively the public key or the private key.

REFERENCES

• 1: A. D. Birrell, A. Hisgen, T. Mann C. Jerian, and G. Swart. The echo distributed file system. SRC Research Report 111, Digital Systems Research Center, 1993.
• 2: Matt Blaze, A cryptographic file system for UNIX, Proceedings of the 1st ACM conference on Computer and communications security, p.9-16, November 03-05, 1993, Fairfax, Virginia, United States [doi>10.1145/168588.168590]
• 3: Peter J. Braam, The Coda Distributed File System, Linux Journal, v.1998 n.50es, June 1998
• 4: G. Cattaneo and G. Persiano. Design and implementation of a transparent cryptographic file system for Unix. Technical report, Dip. Informatica e Appl., Universita di Salerno, July 1997.
• 5: A. O. Freier, P. Karlton, and P. C. Kocher. The ssl protocol : Version 3.0. Internet-draft, Internet Engineering Task Force (IETF), 1996.
• 6: R. G. Guy, J. S. Heidemann, W. Mak, T. W. Page Jr., G. J. Popek, and D. Rothmeier. Implementation of the ficus replicated file system. In Proceedings of the Summer USENIX Conference, pages 63-71, June 1990.
• 7: P. Reiner, T. Page Jr., G. Popek, J. Cook, and S. Crocker. Truffles --- a secure service for widespread file sharing. In Proceedings of the Privacy and Security Research Group Workshop on Network and Distributed System Security, 1994.
• 8: Mahadev Satyanarayanan, Scalable, Secure, and Highly Available Distributed File Access, Computer, v.23 n.5, p.9-18, 20-21, May 1990 [doi>10.1109/2.53351]
• 9: E. Zadok, I. Badulescu, and A. Shender. Cryptfs: a stackable vnode level encryption file system. Technical report, Computer Science Department, Columbia University, 1998.