Eurydice is a compiler from Rust to C. The purpose of Eurydice is to provide a backwards-compatibility story as the verification ecosystem gradually transitions to Rust. New programs can be written in Rust, in turn making them safer and easier to verify; but for legacy environments that cannot yet take a dependency on the Rust toolchain, Eurydice allows generating C code as a stopgap measure.
Currently (late 2023), the flagship example for Eurydice is Kyber, a Post-Quantum cryptographic algorithm authored and verified in Rust for the general public, and compiled to C via Eurydice for Mozilla's NSS library.
In terms of software architecture, Eurydice consumes Rust programs via the Charon infrastructure, then extracts Rust to KaRaMeL's internal AST via a type-driven translation. Once in the KaRaMeL AST, 30+ nano-passes allow going from Rust down to C code. About half of these passes were already implemented for KaRaMeL, the rest of the passes reuse the KaRaMeL infrastructure but were freshly written for Eurydice.
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