CRASH Methodology for Correct-by-construction Attack-tolerant Systems
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Background
Our method uses formal proofs of high-level system requirements then to synthesize code from the proven specification. Within our work on distributed systems we use the following concepts:
- Logic of Events: a simple formal theory of mathematical structure corresponding to message sequence diagrams
- Logic of Events presentation at LADA 2012 by Robert Constable, Mark Bickford, and Vincent Rahli. 2012
- Automated Proof of Authentication Protocols in a Logic of Events by Mark Bickford. 2010
- A Causal Logic of Events in Formalized Computational Type Theory by Mark Bickford, Robert L. Constable. 2005
- Event Classes: abstract description of processes
- Investigating Correct-by-Construction Attack-Tolerant Systems by Robert Constable, Mark Bickford, Robbert Van Renesse. 2010
- Generating Event Logics with Higher-Order Processes as Realizers by Mark Bickford, Robert L. Constable, David Guaspari. 2010
- Component Specification Using Event Classes by Mark Bickford. 2009
The main tool we use is EventML which is a programming and specification language. EventML, built by Vincent Rahli, cooperates with the Nuprl interactive theorem prover at every stage of program development to help programmers ensure correctness, document the code, and support modifications and improvements. It generates an Inductive Logical Form that proves the specification and can also automatically synthesize code.
- Resources for EventML
- EventML documentation and downloads available at http://www.nuprl.org/software/
- EventML Tutorial
- Example of 2/3 consensus in EventML
Code diversity is created during the process. We can introduce variants at the EventML specification and code synthesis.
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- Write the specification in EventML
- Automatically generate and prove an Inductive Logical Form of the specification
- Synthesize code
- Diversify and deploy code
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Step 1 - We write the Scout specification in EventML
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EventML uses classes from the Formal Digital Library to describe events and protocols.
Step 2 - Generate the Inductive Logical Form (ILF)from the Scout specification
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Engaging our diversity in classes and state machines we generate multiple verified versions of the code. Then the final step before deployment is to test the code in the EventML simulator. The result is a correct-by-construction synthesized version of Paxos with multiple code variants.
Example Deployment: ShadowDB
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