Trustworthy Services

Overview

Replication improves the resilience of network services under attack but can also lead to greater vulnerability for both the replicated data and code. Replicating data can lead to loss of secrecy, since the same data is normally stored on each replica. And replicas that use the same code share the same vulnerabilities. So, replicas do not fail independently when under attack.

Solving these problems requires increasing replica independence and performing proactive state and code recovery. Proactive state recovery involves periodically refreshing replica state, including keys. This leads to both new cryptographic protocols and new systems-level design. Proactive code recovery involves periodically changing replica code to maintain failure independence.

Projects

• The Cornell Online Certification Authority (COCA) project uses a novel asynchronous proactive secret sharing scheme to implement a dissemination Byzantine Quorum System. COCA implements a fully asynchronous distributed certificate authority.
• The Cornell Data Exchange (CODEX) project uses the techniques of COCA to implement a secret distribution system. It also provides a general toolkit for building secure distributed services.
• The Proactive Obfuscation project consists of a framework for performing proactive recovery of code as well as state. Semantics-preserving code transformations (called obfuscation) are periodically performed on server code to generate fresh executables for rebooting replicas.

Publications

• Lidong Zhou and Zygmunt J. Haas
  Securing Ad Hoc Networks.
  IEEE Networks Special Issue on Network Security. November/December, 1999.
  
• Lidong Zhou, Fred B. Schneider, and Robbert van Renesse.
  COCA: A Secure Distributed On-line Certification Authority.
  ACM Transactions on Computer Systems 20(4): 329-368 (2002).
  Earlier version: Cornell University Technical Report TR 2000-1828, December 7, 2000.
• Michael A. Marsh and Fred B. Schneider.
  CODEX: A Robust and Secure Secret Distribution System.
  IEEE Transactions on Dependable and Secure Computing. 1(1): 34-47 (2004).
• Lidong Zhou, Fred B. Schneider, and Robbert van Renesse.
  APSS: Proactive Secret Sharing in Asynchronous Systems.
  ACM Transactions on Information and System Security. 8(3): 259-286 (2005).
• Tom Roeder and Fred B. Schneider.
  Proactive Obfuscation.
  In submission.
• Tom Roeder, Rafael Pass, and Fred B. Schneider.
  Multi-Verifier Signatures.
  In preparation.