Project Everest began at Microsoft Research in 2016, aiming to spur research in program verification to produce industrial-grade software. In collaboration with INRIA and Carnegie Mellon University, Project Everest’s goal was to produce drop-in verified replacements of secure communications software used in the HTTPS ecosystem, including TLS, the underlying cryptography, and related subprotocols. Now, almost a decade later, we reflect on the project, sharing both its successes and failures, and look ahead to the next decade of program verification research.

Abstract Syntax Notation One (ASN.1) is a language for structured data exchange between computers, standardized by both ITU-T and ISO/IEC since 1984. The Distinguished Encoding Rules (DER) specify its non-malleable binary format: for a given ASN.1 data type, every value has a distinct, unique binary representation. ASN.1 DER is used in many security-critical interfaces for telecommunications and networking, such as the X.509 public key infrastructure, where non-malleability is essential. However, due to the expressiveness and flexibility of the general-purpose ASN.1 language, correctly parsing ASN.1 DER data formats is still considered a serious security challenge in practice. We present ASN1*, the first formalization of ASN.1 DER with a mechanized proof of non-malleability. Our development provides a shallow embedding of ASN.1 in the F* proof assistant and formalizes its DER semantics within the EverParse parser generator framework. It guarantees that any ASN.1 data encoded using our DER semantics is non-malleable. It yields verified code that parses valid binary representations into values of the corresponding ASN.1 data type while rejecting invalid ones. We empirically confirm that our semantics models ASN.1 DER usage in practice by evaluating ASN1* parsers extracted to OCaml on both positive and negative test cases involving X.509 certificates and Certificate Revocation Lists (CRLs).

Cross-domain applications are rapidly adopting blockchain techniques for immutability, availability, integrity, and interoperability. However, for most applications, global consensus is unnecessary and may not even provide sufficient guarantees. We propose a new distributed data structure: Attested Data Structures (ADS), which generalize not only blockchains but also many other structures used by distributed applications. As in blockchains, data in ADSs is immutable and self-authenticating. ADSs go further by supporting application-defined proofs ( attestations ). Attestations enable applications to plug in their own mechanisms to ensure availability and integrity. We present Charlotte , a framework for composable ADSs. Charlotte deconstructs conventional blockchains into more primitive mechanisms. Charlotte can be used to construct blockchains but does not impose the usual global-ordering overhead. Charlotte offers a flexible foundation for interacting applications that define their own policies for availability and integrity. Unlike traditional distributed systems, Charlotte supports heterogeneous trust: different observers have their own beliefs about who might fail, and how. Nevertheless, each observer has a consistent, available view of data. Charlotte’s data structures are interoperable and composable : applications and data structures can operate fully independently or can share data when desired. Charlotte defines a language-independent format for data blocks and a network API for servers. To demonstrate Charlotte’s flexibility, we implement several integrity mechanisms, including consensus and proof of work. We explore the power of disentangling availability and integrity mechanisms in prototype applications. The results suggest that Charlotte can be used to build flexible, fast, composable applications with strong guarantees.

With an eye toward performance, interoperability, or legacy concerns, low-level system software often must parse binary encoded data formats. Few tools are available for this task, especially since the formats involve a mixture of arithmetic and data dependence, beyond what can be handled by typical parser generators. As such, parsers are written by hand in languages like C, with inevitable errors leading to security vulnerabilities.

The disastrous vulnerabilities in smart contracts sharply remind us of our ignorance: we do not know how to write code that is secure in composition with malicious code. Information flow control has long been proposed as a way to achieve compositional security, offering strong guarantees even when combining software from different trust domains. Unfortunately, this appealing story breaks down in the presence of reentrancy attacks. We formalize a general definition of reentrancy and introduce a security condition that allows software modules like smart contracts to protect their key invariants while retaining the expressive power of safe forms of reentrancy. We present a security type system that provably enforces secure information flow; in conjunction with run-time mechanisms, it enforces secure reentrancy even in the presence of unknown code; and it helps locate and correct recent high-profile vulnerabilities.