Synthetic IV (SIV) encryption modes for JWE

A new draft that ports the AES/SIV mode to JOSE. Provides deterministic authenticated encryption and key-wrapping, as well as nonce-based misuse- resistant authenticated encryption, depending on how the cipher is set up.

Java 8 upgrade

Upgrading the library to make use of language features and classes in Java 8 where that makes sense. The super ticket for suggestions and tracking the work is here.

JWT annotations

Annotations would be good to have. For example, a @JWTClaim annotation to turn a Java object into a JWT claims set.

Benchmark suite

Create a benchmark suite to test the relative performance of the supported JWS and JWE algorithms.