Someone else already touched on this, but I'd really suggest changing
the form for the MD5 hashes being used. Currently the 128-bit value is
being converted to a 32-character hexadecimal representation. I'd
suggest changing it in all text forms to be the 24-character Base-64
encoded form for the 128-bit hash.
I was working on a POV-Ray distribution system the other night, and
implemented the Base-64 conversion for MD5 hashes in Java in about 10
minutes, counting the time needed to correct my stupid index out of
bounds error. Thus, I don't think there will be much burden on
developers.
It makes the strings a little more opaque, but since it's a hash value
anyway, we are not really losing much legibility. It does make the
strings 25% shorter, which could be good for URL's and such. Among other
things, this is the format that Sun adopted for the manifest file format
in .JAR files.
This should be used for URL's and within XML formatting of the data.