A key feature in trusted computing is attestation, which allows encapsulated components (enclaves) to prove their identity to (local or remote) distrusting components. Reasoning about software that uses the technique requires tracking how trust evolves after successful attestation. This process is security-critical and non-trivial, but no existing formal verification technique supports modular reasoning about attestation of enclaves and their clients, or proving end-to-end properties for systems combining trusted, untrusted and attested code. We contribute Cerisier, the first program logic for modular reasoning about trusted, untrusted and attested code, fully mechanized in the Iris separation logic and the Rocq Prover. We formalize a recent proposal, CHERI-TrEE, to extend capability machines with enclave primitives, as an extension to the Cerise capability machine and program logic. Our program logic comes with a universal contract for untrusted code, which captures both capability safety and local enclave attestation. Like Cerise, this universal contract is phrased in terms of a logical relation defining capabilities' authority. We demonstrate Cerisier by proving end-to-end properties for three representative applications of trusted computing: secure outsourced computation, mutual attestation and a modeled trusted sensor component.

Type inference is essential for statically-typed languages such as OCaml and Haskell. It can be decomposed into two (possibly interleaved) phases: a generator converts programs to constraints; a solver decides whether a constraint is satisfiable. Elaboration, the task of decorating a program with explicit type annotations, can also be structured in this way. Unfortunately, most machine-checked implementations of type inference do not follow this phase-separated, constraint-based approach. Those that do are rarely executable, lack effectful abstractions, and do not include elaboration. To close the gap between common practice in real-world implementations and mechanizations inside proof assistants, we propose an approach that enables modular reasoning about monadic constraint generation in the presence of elaboration. Our approach includes a domain-specific base logic for reasoning about metavariables and a program logic that allows us to reason abstractly about the meaning of constraints. To evaluate it, we report on a machine-checked implementation of our techniques inside the Coq proof assistant. As a case study, we verify both soundness and completeness for three elaborating type inferencers for the simply typed λ -calculus with Booleans. Our results are the first demonstration that type inference algorithms can be verified in the same form as they are implemented in practice: in an imperative style, modularly decomposed into constraint generation and solving, and delivering elaborated terms to the remainder of the compiler chain.