We present EverCrypt: a comprehensive collection of verified, high-performance cryptographic functionalities available via a carefully designed API. The API provably supports agility (choosing between multiple algorithms for the same functionality) and multiplexing (choosing between multiple implementations of the same algorithm). Through abstraction and zero-cost generic programming, we show how agility can simplify verification without sacrificing performance, and we demonstrate how C and assembly can be composed and verified against shared specifications. We substantiate the effectiveness of these techniques with new verified implementations (including hashes, Curve25519, and AES-GCM) whose performance matches or exceeds the best unverified implementations. We validate the API design with two high-performance verified case studies built atop EverCrypt, resulting in line-rate performance for a secure network protocol and a Merkle-tree library, used in a production blockchain, that supports 2.7 million insertions/sec. Altogether, EverCrypt consists of over 124K verified lines of specs, code, and proofs, and it produces over 29K lines of C and 14K lines of assembly code. SpecificationsImplementations Spec.Hash val compress (a:alg) (st:words a) (b:block a) : words_state a val init val finish val compress_many val hash EverCrypt.Hash val compress (st:state alg) (b:larr uint8 alg) : Stack unit (requires fun h0 -> ...) (ensures fun h0 _ h1 -> ... /\ repr s h1 == Spec.Hash.compress alg (repr s h0) (as_seq h0 b))val init, finish, compress_many, hash Refines Spec.MD5 val compress: ... val init: ...

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Abstract. Certified programming allows to prove that the program meets its specification. The check of correctness of a program is performed at compile time, which guarantees that the program always runs as specified. Hence, there is no need to test certified programs to ensure they work correctly. There are numerous toolchains designed for certified programming, but F* is the only language that support both general-purpose programming and semi-automated proving. The latter means that F* infers proofs when it is possible and a user can specify more complex proofs if necessary. We work on the application of this technique to a grammarware research and development project YaccConstructor. We present a work in progress verified implementation of transformation of Context-free grammar to Chomsky normal form, that is making progress toward the certification of the entire project. Among other features, F* system allows to extract code in F# or OCaml languages from a program written in F*. YaccConstructor project is mostly written in F#, so this feature of F* is of particular importance because it allows to maintain compatibility between certified modules and those existing in the project which are not certified yet. We also discuss advantages and disadvantages of such approach and formulate topics for further research.

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