TODO.txt

* write test case for FileKeyProvider
* move InMemoryKeyProvider to test module


* simplify Signer interface (we only need to sign arbitrary byte arrays)
  sign(byte[] data, PublicKeyFingerprint fingerprint)?
* move agent signer into a separate package

* Better naming for Digest algorithm (naming from HMAC standard perhaps?)
* Make all internal classes nonpublic (less packages perhaps?)
* Replace InvalidInputException (and friends) with IllegalArgumentException

* write LDAP KeyProvider (reconnecting!)
* sort out CrtAuthServer constructor argument confusion (DigestAlgorithm and secret amounts
  to the same thing)