Consider using secp256k1-jni from Bitcoin-s

[kushti]

Reportedly:

[Libsecp256k1](https://github.com/bitcoin-core/secp256k1) is used to preform cryptographic operations on the secp256k1 curve. This is the curve that bitcoin uses. There is a signficant speedup when using this library compared to java crypto libraries like bouncy castle.

(from https://bitcoin-s.org/docs/secp256k1/secp256k1 )

So it is worth to try to use secp256k1-jni and so use BouncyCastle as a failback option only (for platforms where a native lib wont load)