RFR: ChaCha20 and ChaCha20/Poly1305 Cipher implementations

[Sean Mullan]

On 4/26/18 1:36 PM, Jamil Nimeh wrote:
> Will do.  I made some wording changes there to move away from "96-bit" 
> to "12-byte" also since that probably is more useful to developers.

One other comment is that I think the get methods of 
ChaCha20ParameterSpec should be final. There should be no reason to 
override those methods and it will help ensure that the contract of 
those methods are not being overridden by a subclass incorrectly.

--Sean