DataSealer and encoding (and location)

[Rod Widdowson]

(Mostly for Scott),

As part of the CryptoTransient AttributeDefinition/PrincipalConnector work I
am bringing the (old) DataSealer over from 2.0.

The "port" is relatively straight forward, although testing might be a
challenge.  But I see that it is encoding the blob using Base32 (which has
its own implementation).

This stuff is going to end up as a NameID, so my question is whether this
has to be Base32 (which would require me to port the encoder over as well)
or can we use Base64? Are their SAML implementations out there that mess
with the case of the NameID? Or is this just history>

I'll note that other attribute definitions which go through a similar
manipulation (ComputedID) are encoded using Base64.

There is another question as to where this implementation should live.  For
now it can live in idp-attribute-resolver-impl because that is the only
place it will be used, I'll garnish it with TODOs so that we revisit the
location.  However it feels as though this should really go into a util
directory somewhere.

/Rod