Quarterly Technical Report, April 2002
During this period, we achieved one of the main milestones for the project
by releasing Secure Spread 2.0. This system includes implementation of
five different key agreement protocols and allows evaluation of all of
them under the same system. We have completed evaluation of the system
over local and wide area networks. Details can be found in the paper
We continued our work on the Secure Spread integrated architecture.
Previously, we designed three different solutions of providing confidentiality
of the data, supporting two group communication semantics: Virtual
Synchrony and Extended Virtual Synchrony. Briefly these solutions
- Virtual Synchrony solution: provides the client with a Virtual
Synchrony model, similar to the current layered Secure Spread
implementation. The advantage of this method with respect to the
layered Secure Spread is that it will scale better, particularly in
simple group changes such as joins and leaves.
- Extended Virtual Synchrony solution: provides the client with the
more efficient group communication Extended Virtual Synchrony
model. This solution protects both the
client-daemon channel and the daemon-daemon communication channels, at
the cost of six encryption/decryption operations.
- Optimized Extended Virtual Synchrony solution: similar to the
Extended Virtual Synchrony solution, but in most cases encrypt and decipher
the message only once. Only in messages that are sent just before a
change there will be a need for the messages to be deciphered and
re-encrypted by the daemons. This solution provides a considerable
performance boost, but is fairly complex to implement.
We completed the implementation of the Virtual Synchrony solution and
implemented the building blocks for the Extended Virtual Synchrony
solution. The Extended Virtual Synchrony code was merged with the
main development tree and is currently going under testing and evaluation.
In addition, we designed a flexible architecture that will allow
us to provide all the solutions in a configurable way.
On the Performance of Group Key Agreement Protocols
Technical Report CNDS-2001-5, November 2001.
A condensed form will appear in the Proceedings of the 22nd IEEE International Conference of Distributed Computing Systems, short paper, 2-5 July, Vienna, Austria.
and Gene Tsudik.
Group key agreement is a fundamental building block for secure peer
group communication systems. Several group key agreement protocols
were proposed in the last decade, all of them assuming the existence
of an underlying group communication infrastructure.
This paper presents a performance evaluation of five notable key
agreement protocols for peer groups, integrated with a reliable group
communication system (Spread). They are: Centralized Group Key
Distribution (CKD), Burmester-Desmedt (BD), Steer et al. (STR), Group
Diffie-Hellman (GDH) and Tree-Based Group Diffie-Hellman (TGDH). The
paper includes an in-depth comparison and analysis of conceptual
results and is the first to report practical results in real-life
local and wide area networks. Our analysis of these protocols'
experimental results offers insights into their scalability and
We have released Secure Spread version 2.0 in
We have released Spread version 3.16.2 in
There are several popular programs that use Spread, including Apache-SSL, Apache distributed logging, the native replication in the Postgres database, etc.
Related with the funding agencies of this program, we are
aware of the following projects using the system:
- The Efficient and Scalable Infrastructure Support for Dynamic Coalitions project, a collaboration between University of California at Irvine, Brown University and Johns Hopkins University, uses Spread as communication infrastruture.
- A group in University of Idaho that uses Secure Spread in research.
- A group at SRI is working on specifing the GDH key agreement protocol from Secure Spread using the CAPSL/MuCAPSL language.
- A group from AF Rome Lab is conducting an evaluation of Secure Spread.
- A group at the University of Maryland, College Park uses Spread as part of the Integrated Security Services for Dynamic Coalition Management project
We also participated at the Secure Group Communication Workshop organized
by the NAI Labs, on March 13 2002, Glenwood, Maryland.
So far, we registered over 150 downloads for Secure Spread from our
web site and about 3500 for Spread.
Plans for Next Quarter:
- Continue our work on the integrated architecture. Current plans focus on testing and evaluating the Extended
Virtual Synchrony and finalizing Optimized Extended Virtual Synchrony solution.
- Update the integrated access control and authentication framework based on community feedback.
- Continue to explore the different trade-offs of the different key agreement protocols on wide area networks. We plan
to perform more scenarios using the EMULAB network.
- Continue research into high performance wide area group communication.
Questions or comments to:
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Distributed Systems and Networks Lab|
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Johns Hopkins University
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Baltimore, MD 21218-2686