seems like a lot of effort - could you have moved the map state to rust instead? to invoke the AuthCrypto.verifySignature with just the key?
1. Technical
The contract is given - I'm receiving usernames as CharSequence(String). I could change that, but that would likely require changes in the SQL parser - not simple at all. Alternatively, I could pass the whole CharSequence to Rust - but passing objects over the JNI boundary comes with perf. penalty (when compared to passing primitive) and we avoid that whenever possible. Or I could encode CharSequence content to a temporary offheap buffer and pass just the pointer to Rust. But this brings back some of the questions from the article - like who owns the buffer?
2. Other reasons
I realized this was a possibility only when I was nearly done with the design (this whole endeavor took less than one day) and I felt the urge to finish it. Also: This article wouldn't have been created!