Eric Wustrow

Since ZMap's debut in 2013, networking and security researchers have used the open-source scanner to write hundreds of research papers that study Internet behavior. In addition, ZMap has been adopted by the security industry to build new classes of enterprise security and compliance products. Over the past decade, much of ZMap's behavior---ranging from its pseudorandom IP generation to its packet construction---has evolved as we have learned more about how to scan the Internet. In this work, we quantify ZMap's adoption over the ten years since its release, describe its modern behavior (and the measurements that motivated changes), and offer lessons from releasing and maintaining ZMap for future tools.

Internet users rely on the protocols they use to protect their private information including their identity and the websites they visit. Formal verification of these protocols can detect subtle bugs that compromise these protections at design time, but is a challenging task as it involves probabilistic reasoning about random sampling, cryptographic primitives, and concurrent execution. Existing approaches either reason about symbolic models of the protocols that sacrifice precision for automation, or reason about more precise computational models that are harder to automate and require cryptographic expertise. In this paper we propose a novel approach to verifying privacy-preserving protocols that is more precise than symbolic models yet more accessible than computational models. Our approach permits direct-style proofs of privacy, as opposed to indirect game-based proofs in computational models, by formalizing privacy as indistinguishability of possible network traces induced by a protocol. We ease automation by leveraging insights from the distributed systems verification community to create sound synchronous models of concurrent protocols. Our verification framework is implemented in F* as a library we call Waldo. We describe two large case studies of using Waldo to verify indistinguishability; one on the Encrypted Client Hello (ECH) extension of the TLS protocol and another on a Private Information Retrieval (PIR) protocol. We uncover subtle flaws in the TLS ECH specification that were missed by other models.