Paper 2019/366

Triggerflow: Regression Testing by Advanced Execution Path Inspection

Iaroslav Gridin, Cesar Pereida García, Nicola Tuveri, and Billy Bob Brumley


Cryptographic libraries often feature multiple implementations of primitives to meet both the security needs of handling private information and the performance requirements of modern services when the handled information is public. OpenSSL, the de-facto standard free and open source cryptographic library, includes mechanisms to differentiate the confidential data and its control flow, including runtime flags, designed for hardening against timing side-channels, but repeatedly accidentally mishandled in the past. To analyze and prevent these accidents, we introduce Triggerflow, a tool for tracking execution paths that, assisted by source annotations, dynamically analyzes the binary through the debugger. We validate this approach with case studies demonstrating how adopting our method in the development pipeline would have promptly detected such accidents. We further show-case the value of the tooling by presenting two novel discoveries facilitated by Triggerflow: one leak and one defect.

Available format(s)
Publication info
Preprint. Minor revision.
software testingregression testingcontinuous integrationdynamic program analysisapplied cryptographyside-channel analysisOpenSSL
Contact author(s)
iaroslav gridin @ tuni fi
billy brumley @ tuni fi
2019-04-25: revised
2019-04-11: received
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Creative Commons Attribution


      author = {Iaroslav Gridin and Cesar Pereida García and Nicola Tuveri and Billy Bob Brumley},
      title = {Triggerflow: Regression Testing by Advanced Execution Path Inspection},
      howpublished = {Cryptology ePrint Archive, Paper 2019/366},
      year = {2019},
      note = {\url{}},
      url = {}
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