If you didn't read the article about the HACL* approach, go there first and read it. tl;dr
HACL* is a cryptographic library written in F* that allows translation to C using kremlin. It guarantees memory safety, secret independent computation, and functional correctness with respect to a mathematical specification.
In this second blog post I describe the process of integrating code from HACL*, a researchy crypto library, into NSS, a production library shipping to millions of people, running on a plethora of platforms.