[Colloquium] Reminder [defense] Dickens/Dissertation Defense/Jul 15, 2020

[Rene Noyola]

This is an updated announcement about Bernard Dickens' defense that includes an accessible Zoom link.

Here is the Zoom link to participate:
    
https://uchicago.zoom.us/j/92058421129?pwd=R1c2SWYrT2gzNzZpelFua0F4WFRXZz09 

ID: 920 5842 1129 Password: 893892
    
           Department of Computer Science/The University of Chicago
    
                         *** Dissertation Defense ***
    
    
    Candidate:  Bernard Dickens
    
    Date:  Wednesday, July 15, 2020
    
    Time:  12:00 PM
    
    Place:  remotely via Zoom
    
    Title: Capitalizing on Security, Performance, and Energy Tradeoffs in
    Full Drive Encryption Schemes for Fun and Profit
    
    Abstract:
    The security of data at rest---widely understood as FDE or Full Drive
    Encryption---is an important concern among several in modern computer
    systems. These concerns exist in contention over a set of finite
    resources. For instance: a device that is battery-constrained must
    remain within its energy budget which may change over time, e.g. when
    a device enters "battery-saver mode"; regardless, this device must
    meet certain performance guarantees or the user experience will
    suffer; above all, the data on the device must be secure from
    adversaries; and the device has a finite amount of drive space
    available. At any given moment we trade battery life for performance,
    performance for security, security for drive space, and so on.
    Unfortunately, designing a FDE system that can navigate such
    treacherous tradeoffs efficiently, effectively, and with respect to
    performance and security guarantees is entirely non-trivial. This
    dissertation explores this space of tradeoffs and how we might
    optimize for one concern without violating another given kernel and/or
    user space in-context invariants that might shift over time.
    
    Full drive encryption is especially important for mobile devices
    because they contain large quantities of sensitive data yet are easily
    lost or stolen. As this research demonstrates, the standard approach
    to FDE—the AES block cipher in XTS mode—is 3-5x slower than
    unencrypted storage. Authenticated encryption based on stream ciphers
    is already used as a faster alternative to AES in other contexts, such
    as HTTPS, but the conventional wisdom is that stream ciphers are
    unsuitable for FDE. Used naively in drive encryption, stream ciphers
    are vulnerable to attacks, and mitigating these attacks with on-drive
    metadata is generally believed to ruin performance.
    
    We address the difficulty of using stream ciphers for FDE with
    StrongBox, a stream cipher based FDE layer that is a drop-in
    replacement for dm-crypt, the standard Linux FDE module based on
    AES-XTS. StrongBox introduces a system design and on-drive data
    structures that exploit certain properties of filesystems to avoid
    costly rekeying penalties and a counter stored in trusted hardware to
    protect against attacks. We implement StrongBox and SwitchCrypt on an
    ARM big.LITTLE mobile processor and test its performance under
    multiple popular production filesystems.
    
    We push the envelope further with SwitchCrypt, a software mechanism
    that allows us to move beyond merely making stream ciphers available
    for FDE. SwitchCrypt enables practical navigation of the tradeoff
    space made by balancing competing security and latency requirements
    via cipher switching in space or time. Our key insight in achieving
    low-overhead switching is to leverage the overwrite-averse,
    append-mostly behavior of underlying solid-state storage to trade
    throughput for reduced energy use and/or certain security properties.
    Similar to StrongBox, we implement SwitchCrypt on an ARM big.LITTLE
    mobile processor and test its performance under the popular F2FS LFS.
    We provide empirical results demonstrating the conditions under which
    different switching strategies are optimal through the exploration of
    four cases studies.
    
    Finally, with HASCHK, we consider the same stream cipher based
    cryptographic primitives in an alternative domain: data in motion
    rather than at rest. Specifically: securing data downloads over the
    internet. Such downloads come with many risks, including the chance
    that the resource has been corrupted, or that an attacker has replaced
    your desired resource with a compromised version. The de facto
    standard for addressing this risk is the use of checksums coupled with
    a secure transport layer; users download a resource, compute its
    checksum, and compare that with an authoritative checksum. Problems
    with this approach include (1) user apathy---for most users,
    calculating and verifying the checksum is too tedious; and (2)
    co-hosting---an attacker who compromises a resource can trivially
    compromise a checksum hosted on the same system. The co-hosting
    problem remains despite advancements in tools that automate checksum
    verification and generation. In this dissertation we propose HASCHK, a
    resource verification protocol expanding on de facto checksum-based
    integrity protections to defeat co-hosting while automating the
    tedious parts of checksum verification to secure "data in motion" over
    the internet.
    
    StrongBox, SwitchCrypt, and HASCHK together demonstrate that security
    is indeed a paramount concern and valid dimension with which to trade
    off alongside other tier-one concerns without compromising data
    security or requiring obscene performance sacrifices, all while
    staying within a shifting energy budget.
    
    Bernard's advisor is Prof. Henry Hoffmann
    
    Login to the Computer Science Department website for details,
    including a draft copy of the dissertation:
    
     https://newtraell.cs.uchicago.edu/phd/phd_announcements#bd3
    
    =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
    Margaret P. Jaffey            margaret at cs.uchicago.edu
    Department of Computer Science
    Student Support Rep (JCL 350)              (773) 702-6011
    The University of Chicago      http://www.cs.uchicago.edu
    =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
    

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