Metal: A Metadata-Hiding File Sharing System

Weikeng Chen and Raluca Ada Popa

EECS Department, University of California, Berkeley

Technical Report No. UCB/EECS-2020-11

January 10, 2020

http://www2.eecs.berkeley.edu/Pubs/TechRpts/2020/EECS-2020-11.pdf

<p>File sharing systems like Dropbox offer insufficient privacy since a compromised server can see the file content in the clear. Though encryption can hide such content from the servers, metadata leakage remains significant. It is promising to develop a file sharing system that hides such metadata--including user identities and file access patterns.</p>

<p>Metal is the first file sharing system that hides such metadata from malicious users with a latency of only a few seconds. The core of Metal is <i>a new two-server multi-user ORAM scheme</i>, which is secure against malicious users, together with metadata-hiding access control and file sharing.</p>

<p>Compared with the state-of-the-art malicious-user file sharing scheme PIR-MCORAM (which does not hide user identities), Metal hides the user identities and is 500x faster (in terms of amortized latency) or 10^5x faster (in terms of worst-case latency).</p>

Advisors: Raluca Ada Popa

BibTeX citation:

@mastersthesis{Chen:EECS-2020-11,
    Author= {Chen, Weikeng and Popa, Raluca Ada},
    Title= {Metal: A Metadata-Hiding File Sharing System},
    School= {EECS Department, University of California, Berkeley},
    Year= {2020},
    Month= {Jan},
    Url= {http://www2.eecs.berkeley.edu/Pubs/TechRpts/2020/EECS-2020-11.html},
    Number= {UCB/EECS-2020-11},
    Note= {Dedicated to my family members: Qiaozhu, Binbin, Wenkeng, Weijun, and Zirui.},
    Abstract= {<p>File sharing systems like Dropbox offer insufficient privacy since a compromised server can see the file content in the clear. Though encryption can hide such content from the servers, metadata leakage remains significant. It is promising to develop a file sharing system that hides such metadata--including user identities and file access patterns.</p>

<p>Metal is the first file sharing system that hides such metadata from malicious users with a latency of only a few seconds. The core of Metal is <i>a new two-server multi-user ORAM scheme</i>, which is secure against malicious users, together with metadata-hiding access control and file sharing.</p>

<p>Compared with the state-of-the-art malicious-user file sharing scheme PIR-MCORAM  (which does not hide user identities), Metal hides the user identities and is 500x faster (in terms of amortized latency) or 10^5x faster (in terms of worst-case latency).</p>},
}

EndNote citation:

%0 Thesis
%A Chen, Weikeng 
%A Popa, Raluca Ada 
%T Metal: A Metadata-Hiding File Sharing System
%I EECS Department, University of California, Berkeley
%D 2020
%8 January 10
%@ UCB/EECS-2020-11
%U http://www2.eecs.berkeley.edu/Pubs/TechRpts/2020/EECS-2020-11.html
%F Chen:EECS-2020-11