| NSF Org: |
CNS Division Of Computer and Network Systems |
| Recipient: |
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| Initial Amendment Date: | September 17, 2009 |
| Latest Amendment Date: | August 6, 2010 |
| Award Number: | 0959138 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Samuel M. Weber
CNS Division Of Computer and Network Systems CSE Directorate for Computer and Information Science and Engineering |
| Start Date: | September 1, 2009 |
| End Date: | August 31, 2011 (Estimated) |
| Total Intended Award Amount: | $299,967.00 |
| Total Awarded Amount to Date: | $299,967.00 |
| Funds Obligated to Date: |
FY 2010 = $147,354.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
3141 CHESTNUT ST PHILADELPHIA PA US 19104-2875 (215)895-6342 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
3141 CHESTNUT ST PHILADELPHIA PA US 19104-2875 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | TRUSTWORTHY COMPUTING |
| Primary Program Source: |
01001011DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.070 |
ABSTRACT
As the Tor network has grown since 2003 to almost 2000 volunteer relays, the anonymity that it can provide has grown too. This project is measuring Tor's network characteristics and usage, laying the foundation for evaluating its anonymity and improving performance. The project is addressing three components of this challenge. First, it invents new algorithms for collecting Tor network load and usage data safely, including new metrics to ensure that collected data doesn't harm privacy too much yet is still useful for research. Second, it collects and make available aggregated data about the live Tor network over time, and design and deploy new tools to manipulate and understand this data. Third, it identifies which measurements are necessary to support the wider performance and anonymity research questions, do the measurements, and feed the results into the anonymity community's ongoing research projects.
Research Activity 1: Directory and network data. Analyze patterns in directory authority opinions to tune them for better network anonymity and performance, and then track long-term characteristics like churn rate so researchers can simulate design changes.
Research Activity 2: Performance data. Design and perform measurements
to better understand why the Tor network has high (and highly variable) latency. Early investigations show that queuing inside Tor's relays contributes to this latency. Discovering what exactly is wrong with Tor's congestion control mechanisms will allow designers to learn whether proposed
improvements actually help. The project will also investigate other theories of how to improve performance, such as: a) Tor's round-robin scheduling approach should prioritize interactive traffic over bulk traffic; b) incentive systems could encourage users to relay traffic; c) Tor's path selection
algorithms should load balance better over the relays; and d) clients should handle variable latency and connection failures by dynamically adapting to observed network quality.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Tor is a free-software anonymizing overlay network that helps people around the world use the Internet in safety. As the Tor network has grown since 2003 to more than 2500 volunteer relays, the anonymity that it can provide has grown too. With a user base now numbering in the hundreds of thousands, however, the performance of the network has suffered. This project is measuring Tor's network characteristics and usage, laying the foundation for evaluating its anonymity and improving performance.
The project focuses on five main contributions.
First, we've been gathering and providing statistics about the live Tor network, so researchers can better understand the right problems to solve. We make the raw data available to the public so anybody can do analysis:
https://metrics.torproject.org/data.html
Second, we've been designing and publicizing exemplar algorithms for safely aggregating user data, and walking through the ethical, moral, and legal requirements for being safe with this data:
https://metrics.torproject.org/graphs.html
Third, we are doing our own analysis on the data we collect, for example to discover and correct problems in Tor's network load balancing algorithms. The stable and low latencies shown in the past year are the result of some of these performance improvements:
https://metrics.torproject.org/performance.html
Fourth, we're directly working with other research groups in the form of site visits to do Tor talks, answer questions from the grad students and post-docs, and generally help make sure anonymity research at other institutions is solving real and important problems:
https://www.torproject.org/research
Fifth, we aim to be a role model for open source development as well as open design for security tools. Tor's source code and specifications are open. Beyond its original design document (published as an academic paper), Tor provides a clear and published set of RFC-style specifications describing exactly how it is built, why it made each design decision, and what security properties it aims to offer. The Tor developers conduct design discussion in the open, on public development mailing lists, and the public development proposal process provides a clear path by which other researchers can participate. Academic researchers at UMass Amherst, University of Bamberg (Germany), Waterloo (Canada), UIUC, Colorado, University of Wurzburg (Germany), and others have participated in the proposal process.
Last Modified: 08/31/2011
Modified by: Roger Dingledine
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