- Should we be concerned about deserialize doing a string eval on the input,
   especially if that input came from some disk file they gave us in read()?

 - The only remaining issue with supporting 5.6 is on 64-bit Perls, where
   Math::Prime::Util's random prime generator doesn't work.  5.6.2 can't
   represent integers in the range 2^50 to 2^64.  This version of Perl is
   just fundamentally broken and a _huge_ pain to work around.

 - The test suites do almost no failure testing.  Use Devel::Cover to see all
   the failure cases that aren't covered.

 - Look into allowing other SHA hashes for PSS and OAEP.

 - Decide if RIPEMD160 should be non-optional.  Module version 0.05 looks like
   it has an excellent test pass rate.

 - t/16-serialize.t is just verifying we don't die horribly.  We should verify
   that it's actually working.

 - t/90-release-perlcritic.t
   t/92-release-pod-coverage.t

 - The test suite is still using a lot of randomness.  Find a way to reduce it.