[tahoe-dev] [tahoe-lafs] #957: embed security metadata in URL

[tahoe-lafs]

#957: embed security metadata in URL
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 Reporter:  zooko                               |           Owner:  somebody 
     Type:  defect                              |          Status:  new      
 Priority:  major                               |       Milestone:  undecided
Component:  code                                |         Version:  1.6.0    
 Keywords:  newcaps newurls integrity redirect  |   Launchpad_bug:           
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Changes (by davidsarah):

  * keywords:  newcaps newurls integrity => newcaps newurls integrity
               redirect


Comment:

 In order for a petrified URL not to be subject to a rollback attack, it
 would need to include a hash of the final contents (I was mistaken about
 this in comment:2). The final version number is not sufficient, if the
 write cap might have been compromised. Including a hash would make the URL
 huge. (I/we had some ideas about how to obtain relatively short caps to a
 specific version of a mutable object, but they're for the new cap
 formats.)

 We're starting to think that petrification should be implemented in terms
 of permanent redirects ("moved permanently"). I.e. a petrified object is
 just a mutable object that has been permanently redirected to an immutable
 URI. To record that in a parent directory (#956), you would just update
 the link in the parent to point to the new URI.

 The advantage of this is that you can upload the final contents (either a
 single file or a tree) as normal, check that they are correct, and only
 then make the redirect. Also you can permanently redirect to a new mutable
 object using the same mechanism, which is probably what you would want to
 do if you've accidentally given away a write cap.

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Ticket URL: <http://allmydata.org/trac/tahoe/ticket/957#comment:5>
tahoe-lafs <http://allmydata.org>
secure decentralized file storage grid