RFR: ChaCha20 and ChaCha20/Poly1305 Cipher implementations

[Adam Petcher]

On 3/28/2018 2:48 AM, sha.jiang at oracle.com wrote:

> Would you like to move this method to a test lib class, like 
> test/lib/jdk/test/lib/Utils.java? In fact, this class has a method, 
> named toHexString, for converting bin to hex.

This method appears to be the same as Convert.hexStringToByteArray that 
I added to jdk.test.lib along with the field arithmetic implementation. 
That code is not incorporated yet, but the Poly1305 code depends on the 
field arithmetic code, anyway. So adding this dependency may be reasonable.