A constant-time key-value map experiment.
This is pretty stupid and not well tested or audited. It's just an experiment. I can't even really see why anyone would ever want to do this. If this seems like the solution to your problem, you probably have the wrong problem. 💁
If you don't know how to safely use the crypto/subtle package, you will never be able to use this package in a safe way.
This was loosely inspired by this article by Andy Wingo.