Year: 2014
Type: dissertation
Abstract: Cloud-based services are now an integral part of everyday lives of many users. \nIndeed, users who do not use Facebook, Gmail, Dropbox, GoogleDrive, QQ, Baidu or \nsimilar services are now a rarity. These services offer seamless integration of \nuser data with multiple user-owned devices, reliable online backup, and enable \neasy and instant communications between users. Such features, at an affordable \nprice of zero dollars, make these services very popular, even though they are \nan antithesis to user privacy, and help create large-scale surveillance programs \nsuch as NSA PRISM. Several mechanisms have been proposed and implemented to make \nthese services privacy-friendly. Most past proposals rely on public key systems \nwith user-managed private keys, or password-based symmetric encryption. \nWe explore a symmetric-key approach without password-derived keys \n to facilitate end-to-end encryption of \nstored user data (e.g., cloud storage) and communication messages (e.g., \nweb-based email). We propose Keyfob, a key management scheme for easy key \ntransfer between user-owned devices, and between users. Keyfob uses high-entropy \nrandom keys for encryption instead of password-derived keys, and leverages \nDH-EKE (Bellovin and Merritt, IEEE S&P 1992) with weak secrets for secure key \ntransfer. Each user needs to manage one user-master key, and all other keys are \nderived from that master key or a pair-wise shared master key. We implemented Keyfob \nas a Firefox extension using the Firefox Sync service, which implements an EKE \nvariant. Keyfob can make several applications and services privacy-friendly, if \nappropriate intermediate layers are implemented, e.g., as plugins between a \ntarget cloud-service application and the Keyfob extension. We have implemented \ntwo such plugins to support encrypted Dropbox (in desktop and Android) and Gmail \n(in desktop). Our hope in proposing Keyfob with a symmetric-key approach is to \nhighlight challenges in such a lesser-explored mechanism, and attract \nresearchers towards the long-standing problem of enabling end-to-end encryption \nin a cloud-dominated environment.
Author: Suryadipta Majumdar
Language: English
Subfield: Information Systems
Field: Computer Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2148520178