Waoh, made the mistake and had a look at:
https://github.com/gimer/curve25519-sign-test/blob/master/src/nxt/crypto/Curve25519.javaMy eyes are bleeding as does my computer science heart.
Mathematicians, physicists and cryptographists should NOT write code. Please! Pleeeease!

You want us to audit but reading this is like reading a best-seller that has been injected grammar errors and typos each in every sentence. So, how to find the errors in content if you can barely tell them apart from the former ones.
I really get the impression that programmed cryptography is not so difficult in the end; except when people having no idea how to write it down write it down.

Sorry for being emotional.
But you are aware, that this is almost exactly the same file, as used in NRS... :>