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A Methodology for Analyzing the performance of Authentication Protocols. Alan Harbitter Daniel A. Menasce. Presented by Rob Elkind. Outline. Introduction Kerberos – and extensions Kerberos with Proxy Methodology Simulations – Multiple Realm and Mobile with proxy Conclusion.
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A Methodology for Analyzing the performance of Authentication Protocols Alan Harbitter Daniel A. Menasce Presented by Rob Elkind Analyzing the Performance of Authentication Protocols
Outline • Introduction • Kerberos – and extensions • Kerberos with Proxy • Methodology • Simulations – Multiple Realm and Mobile with proxy • Conclusion Analyzing the Performance of Authentication Protocols
Introduction • Use of new modeling methodology for analyzing authentication protocols • Closed queuing network model • Two Kerberos examples will be tested • Designed to explicitly model performance new protocol design including asymmetric and symmetric encryption Analyzing the Performance of Authentication Protocols
Kerberos Overview Analyzing the Performance of Authentication Protocols
Kerberos Realms • Kerberos realms - networked collection of workstations, servers, and a single master KDC which must: • 1. maintain a database of matching user IDs and hashed passwords for registered Kerberos users • 2. maintain shared secret keys with each registered application server • 3. maintain shared secret keys with remote KDCs in other realms • 4. propagate new or changed secret keys and database updates to slave KDCs. Analyzing the Performance of Authentication Protocols
Public Key Cryptography • Increase scalability • Smaller key shared space ~ n2 vs. n for n users • Improved Security • Proposals: • PKINIT (core specification) • PKCROSS • PKTAPP Analyzing the Performance of Authentication Protocols
PKINIT Overview Analyzing the Performance of Authentication Protocols
PKCROSS Overview Analyzing the Performance of Authentication Protocols
PKDA Overview (PKTAPP) Analyzing the Performance of Authentication Protocols
Proxy server with Kerberos • Isolate client and server for security purposes • Offload processing from mobile host or network • IAKERB • Charon Analyzing the Performance of Authentication Protocols
Methodology • Build model • Validate • Change parameters • Analyze results • Add “What ifs” Analyzing the Performance of Authentication Protocols
Modeling Topology multiple-realm Analyzing the Performance of Authentication Protocols
Validation of Model Analyzing the Performance of Authentication Protocols
“What-If” Analyses • Vary input parameters to reflect various real world conditions • Reflects sensitivity to various operational environments • Gives insight into general performance characteristics of the protocol design Analyzing the Performance of Authentication Protocols
Analysis of Public-Key-Enabled Kerberos in Large Networks • Compare PKTAPP and PKCROSS • Simulate using closed queuing network model • Use skeleton software to model real world protocol • When is it more efficient to authenticate to a central KDC than to individual application servers? Analyzing the Performance of Authentication Protocols
PKCROSS vs. PKTAPP Analyzing the Performance of Authentication Protocols
“What-Ifs” Results Analyzing the Performance of Authentication Protocols
Analysis Of Public-key-enabled Kerberos InMobile Computing Environments • Reduce the number of public/private key operations performed on the mobile platform. • When a proxy is used, maintain the option to preserve the encrypted data stream through the proxy. • Retain the standard Kerberos formats for messages sent to the KDC and application server. • Preserve the semantics of Kerberos. Analyzing the Performance of Authentication Protocols
M-PKINIT Analyzing the Performance of Authentication Protocols
MP-PKINIT Analyzing the Performance of Authentication Protocols
Modeling Topology M&MP-PKINIT • Can use same model as before • Substitute a mobile client for client • Wireless network for LAN • Proxy server for local KDC • Adjust branching probabilities to reflect new model paths Analyzing the Performance of Authentication Protocols
Model Results Analyzing the Performance of Authentication Protocols
Model vs. Simulation Analyzing the Performance of Authentication Protocols
“What-If” Analysis Analyzing the Performance of Authentication Protocols
More “What-Ifs” Analyzing the Performance of Authentication Protocols
Conclusions • Closed queuing model with class switching is a useful tool for analyzing performance in security protocols – supports wide range of operating conditions • Skeleton implementation is a good way to work with new ideas that may not be operational yet • PKCROSS outperforms PKTAPP for authenticating to more than one server • Proxy server benefits 2G speeds but not 3G speeds Analyzing the Performance of Authentication Protocols
Thoughts • Well written and presented, clear and detailed • Good procedural methodology • Would be nice to see “What-Ifs” done on the test bed and compared to model as well • Skeleton makes assumptions that may alter results when performed with real implementation Analyzing the Performance of Authentication Protocols
Questions? Analyzing the Performance of Authentication Protocols