I'll add a high-assurance implementation from Galois to that which is probably not constant time. Their blog and Github has quite a few useful tools. https://g

I'll add a high-assurance implementation from Galois to that which is probably not constant time. Their blog and Github has quite a few useful tools. https://galois.com/blog/2013/09/high-assurance-base64/ https://galois.com/blog/2013/09/high-assurance-base64/ Also, anyone wanting constant time implementation might just run a verified implementation through something like FaCT or Jasmin: https://cseweb.ucsd.edu/~dstefan/pubs/cauligi:2017:fact.pdf https://cseweb.ucsd.edu/~dstefan/pubs/cauligi:2017:fact.pdf https://acmccs.github.io/papers/p1807-almeidaA.pdf https://acmccs.github.io/papers/p1807-almeidaA.pdf