PD-DM: An efficient locality-preserving block device mapper with plausible deniability

Open access

Abstract

Encryption protects sensitive data from unauthorized access, yet is not sufficient when users are forced to surrender keys under duress. In contrast, plausible deniability enables users to not only encrypt data but also deny its existence when challenged. Most existing plausible deniability work (e.g. the successful and unfortunately now-defunct TrueCrypt) tackles “single snapshot” adversaries, and cannot handle the more realistic scenario of adversaries gaining access to a device at multiple time points. Such “multi-snapshot” adversaries can simply observe modifications between snapshots and detect the existence of hidden data. Existing ideas handling “multi-snapshot” scenarios feature prohibitive overheads when deployed on practically-sized disks. This is mostly due to a lack of data locality inherent in certain standard access-randomization mechanisms, one of the building blocks used to ensure plausible deniability.

In this work, we show that such randomization is not necessary for strong plausible deniability. Instead, it can be replaced by a canonical form that permits most of writes to be done sequentially. This has two key advantages: 1) it reduces the impact of seek due to random accesses; 2) it reduces the overall number of physical blocks that need to be written for each logical write. As a result, PD-DM increases I/O throughput by orders of magnitude (10–100× in typical setups) over existing work while maintaining strong plausible deniability against multi-snapshot adversaries.

Notably, PD-DM is the first plausible-deniable system getting within reach of the performance of standard encrypted volumes (dm-crypt) for random I/O.

[1] Bonnie++. “http://www.coker.com.au/bonnie++”.

[3] TrueCrypt. “http://truecrypt.sourceforge.net/”.

[5] R. Anderson, R. Needham, and A. Shamir. The stegano-graphic file system. In Information Hiding, pages 73–82. Springer, 1998.

[6] C. C. Anrin Chakraborti and R. Sion. DataLair: Efficient block storage with plausible deniability against multi-snapshot adversaries. Proceedings on Privacy Enhancing Technologies, 2017(3), 2017.

[7] D. Beaver. Plug and play encryption. In Advances in Cryptology – CRYPTO’97, pages 75–89. springer.

[8] E.-O. Blass, T. Mayberry, G. Noubir, and K. Onarlioglu. Toward robust hidden volumes using write-only oblivious ram. In Proceedings of the 2014 ACM SIGSAC Conference on Computer and Communications Security, pages 203–214. ACM, 2014.

[9] R. Canetti, C. Dwork, M. Naor, and R. Ostrovsky. Deniable encryption. In Advances in Cryptology – CRYPTO’97, pages 90–104. Springer, 1997.

[10] R. M. Corless, G. H. Gonnet, D. E. Hare, D. J. Jeffrey, and D. E. Knuth. On the lambertw function. Advances in Computational mathematics, 5(1):329–359, 1996.

[11] P. Desnoyers. Analytic models of ssd write performance. Trans. Storage, 10(2):8:1–8:25, Mar. 2014.

[12] P. Desnoyers. Analytic models of SSD write performance. ACM Transactions on Storage (TOS), 10(2):8, 2014.

[13] F. Douglis and J. Ousterhout. Log-structured file systems. In COMPCON Spring’89. Thirty-Fourth IEEE Computer Society International Conference: Intellectual Leverage, Digest of Papers., pages 124–129. IEEE, 1989.

[14] J. Dursi. On random vs. streaming I/O performance; or seek(), and you shall find – eventually, 2015. “http://simpsonlab.github.io/2015/05/19/io-performance/”.

[15] C. W. Fletcher, L. Ren, A. Kwon, M. van Dijk, and S. Devadas. Freecursive ORAM:[nearly] free recursion and integrity verification for position-based oblivious ram. In ACM SIGPLAN Notices, volume 50, pages 103–116. ACM, 2015.

[16] P. Gasti, G. Ateniese, and M. Blanton. Deniable cloud storage: sharing files via public-key deniability. In Proceedings of the 9th annual ACM workshop on Privacy in the electronic society, pages 31–42. ACM, 2010.

[17] J. Han, M. Pan, D. Gao, and H. Pang. A multi-user steganographic file system on untrusted shared storage. In Proceedings of the 26th Annual Computer Security Applications Conference, pages 317–326. ACM, 2010.

[18] J. Hinks. Nsa copycat spyware could be snooping on your hard drive, 2015. “https://goo.gl/Ktesvl”.

[19] R. P. W. J. Assange and S. Dreyfus. Rubber-hose:cryptographically deniable transparent disk encryption system, 1997. “http://marutukku.org”.

[20] C. M. Kozierok. Access time, 2001. “http://pcguide.com/ref/hdd/perf/perf/spec/pos_Access.htm”.

[21] C. M. Kozierok. Seek time, 2001. “http://pcguide.com/ref/hdd/perf/perf/spec/posSeek-c.html”.

[22] L. Mathews. Adobe software may be snooping through your hard drive right now, 2014. “https://goo.gl/lXzPS3”.

[23] A. D. McDonald and M. G. Kuhn. StegFS: A stegano-graphic file system for Linux. In Information Hiding, pages 463–477. Springer, 1999.

[24] J. Mull. How a Syrian refugee risked his life to bear witness to atrocities. Toronto Star Online, posted 14-March-2012, 2012. “https://goo.gl/QsivgB”.

[25] W. Norcott and D. Capps. IOZone filesystem benchmark, 2016. “http://www.iozone.org/”.

[26] H. Pang, K.-L. Tan, and X. Zhou. StegFS: A steganographic file system. In Data Engineering, 2003. Proceedings. 19th International Conference on, pages 657–667. IEEE, 2003.

[27] T. Peters, M. Gondree, and Z. N. J. Peterson. DEFY: A deniable, encrypted file system for log-structured storage. In 22nd Annual Network and Distributed System Security Symposium, NDSS 2015, San Diego, California, USA, February 8-11, 2014, 2015.

[28] M. Rosenblum and J. K. Ousterhout. The design and implementation of a log-structured file system. ACM Transactions on Computer Systems (TOCS), 10(1):26–52, 1992.

[29] A. Skillen and M. Mannan. On implementing deniable storage encryption for mobile devices. 2013.

[30] WhisperSystems. Github: Whispersystems/whisperyaffs: Wiki, 2012. “https://github.com/WhisperSystems/WhisperYAFFS/wiki”.

[31] X. Zhou, H. Pang, and K.-L. Tan. Hiding data accesses in steganographic file system. In Data Engineering, 2004. Proceedings. 20th International Conference on, pages 572–583. IEEE.

Journal Information

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 2513 2513 18
PDF Downloads 75 75 9