[tahoe-lafs-trac-stream] [tahoe-lafs] #1906: constant-time directory lookup

[tahoe-lafs]

#1906: constant-time directory lookup
-------------------------+-------------------------------------------------
     Reporter:           |      Owner:  davidsarah
  davidsarah             |     Status:  new
         Type:           |  Milestone:  undecided
  enhancement            |    Version:  1.9.2
     Priority:  normal   |   Keywords:  performance directory database
    Component:  code-    |  newcaps research
  dirnodes               |
   Resolution:           |
Launchpad Bug:           |
-------------------------+-------------------------------------------------
Changes (by davidsarah):

 * keywords:  performance directory database newcaps => performance
     directory database newcaps research


Comment:

 A complication is that it must be possible to derive both the child
 writecap from the parent writecap and childname, and the child readcap
 from the parent readcap and childname. This requires the following diagram
 to commute:
 {{{
   Write_parent × childname -> Write_child
         |                          |
         v                          v
    Read_parent ● childname ->  Read_child
 }}}
 where the downward arrows, '×', and '●' are feasibly computable but one-
 way operations. This seems like some kind of homomorphic encryption, but
 the constructions I've tried so far don't quite work.

-- 
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1906#comment:2>
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