DEFY: A Deniable File System for Flash Memory

• Main Author: Peters, Timothy M
• Format: Others
• Published: DigitalCommons@CalPoly 2014
• Subjects: YAFFS; Cryptography; Databases and Information Systems; Information Security
• Online Access: https://digitalcommons.calpoly.edu/theses/1230; https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=2301&context=theses

While solutions for file system encryption can prevent an adversary from determining the contents of files, in situations where a user wishes to hide even the existence of data, encryption alone is not enough. Indeed, encryption may draw attention to those files, as they most likely contain information the user wishes to keep secret, and coercion can be a very strong motivator for the owner of an encrypted file system to surrender their secret key. Herein we present DEFY, a deniable file system designed to work exclusively with solid-state drives, particularly those found in mobile devices. Solid-state drives have unique properties that render previous deniable file system designs impractical or insecure. Further, DEFY provides features not offered by any single prior work, including: support for multiple layers of deniability, authenticated encryption, and an ability to quickly and securely delete data from the device. We have implemented a prototype based on the YAFFS and WhisperYaffs file systems. An evaluation shows DEFY performs comparatively with WhisperYaffs.