implementation of verification page

Mike Linksvayer ml at
Wed Jul 9 22:21:00 EDT 2003

On Thu, 10 Jul 2003 09:17:10 +1000, "Ryan Booker"
<ryanbooker at> said:
> > * The hash published at the above URL doesn't match that of the file
> at
> >
> <
> Feel_Safe_-_07_-_Pinstripe.mp3>
> >
> I'm not sure what you mean by "the hash"?  Please clarify, I'm keen to
> iron all this out before putting the "real" site and content live.

The file's hash is used to identify the file in the verification RDF. 
You calculate the file's hash when publishing the RDF.  Random person who
has the file can also calculate the file's hash.  That's how they know
that your verification page is about the file they have in hand.

So the RDF embedded in
says (excerpt)

  <Work rdf:about="urn:sha1:MSMBC5VEUDLTC26UT5W7GZBAKZHCY2MD">
which means the enclosed statements concern content with a base32-encoded
SHA1 hash value of "MSMB...".

$ bitcollider -p

The "bitprint" value before the period is the file's base32-encoded SHA1
hash.  "TY2N..." != "MSMB...".

NB, "bitcollider" is a tool that extracts metadata from a variety of
files.  If you run it without the -p flag it will attempt to submit the
extracted metadata to <>, another site I'm involved with.
 Available at <>.

However, using a cc-tagging tool rather than doing the tagging and RDF
generation "by hand" will be much less error prone.  Currently the only
option is, which will place the appropriate metadata in your mp3
file and print out the appropriate RDF for your verification page. 
Available at <>.  It's only command-line
and on most systems will require installing several Perl modules.  Sorry
about that.  An easier-to-install-and-use tool is high priority.

Also available at <> is, which
will extract the license claim URL from an MP3, hash the file, and check
to see that RDF published at the license claim URL matches the hash,
printing out the license URL if all goes well or complaining if not.  You
can use this tool (same caveats as to verify that your file is
tagged correctly and that your verification page has good corresponding

> > * The content of TCOP should be "2003 The Buzzeddie Family licensed
> to
> > the public under
> > verify at
> >
> 0just%20to%20feel%20safe"
> >
> No problem.  Didn't realise this was a standard, I only thought the
> "verify at" was the standard.  Makes sense to have a complete TCOP
> standard.

You read <> correctly. 
One change I think I'm going to make is to specify the exact format of
the entire contents of TCOP, leaving a slight bit less to chance.

> Also puts it in the users face when they visit the site rather than
> them having to follow a link buried in a file they probably wont look
> at.  This would serve the purpose of raising awareness of the use of
> embedded licenses and that there are artists who value the ability to
> trade files and the benefits trading gives listeners and musicians (at
> least those who aren't madonna).


> No problem.  I live in Australia, but have been following creative
> commons and "lessig"'s work since learning of them.  Really great
> ideas.  Getting the mug punter to understand and/or care is now the
> challenge.
> We don't even have a real fair use doctrine in this country, which
> makes open licenses even more important.  I wonder if it could be
> extended to explicitly add fair use rights etc to a hard media (ie
> CD).

Interesting.  Sounds unfortunate.  CC licenses say

"2. Fair Use Rights. Nothing in this license is intended to reduce,
limit, or restrict any rights arising from fair use, first sale or other
limitations on the exclusive rights of the copyright owner under
copyright law or other applicable laws."

which makes it really clear that fair use rights remain untouched by a CC
license (I suppose someone could naively think that a "No Derivatives"
license would kill any fair use rights ... not so).  Doesn't help if you
don't have any fair use rights to begin with. :-(  I suppose that as the
US pushes harsher IP laws on other countries it isn't also pushing
relatively liberal fair use provisions.  Hopefully I'm being too cynical.
 Also, IANAL, etc.
  Mike Linksvayer

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