[tahoe-dev] Tahoe Access Control

Greg Troxel gdt at ir.bbn.com
Fri Jun 3 03:28:20 PDT 2011


Thanks - I see that in docs/about.rst#access-control the functionality
is explained.   Certainly I see that if the dir has a readcap as the
link, even a dir writecap doesn't magically augment that.  I was focused
on the case where the tree is rw and someone has a readcap.


But, in wiki:Capabilities, it says that a directory is just a mutable
file with special interpretation.   So I think it would help to have a
page perhaps wiki:Directory that explains the format of the contents of
a directory.

So, it seems that a directory writecap enables one to:

  change the directory (as expected)

  read the write part of writecaps stored in the directory

while a directory readcap enables one only to

  read the read part of writecaps stored in the directory, or the
  matching readcap that must always be present next to a readcap


But I still don't understand whether there is some incremental write
part of the writecap (the part that's omitted when diminishing to a
readcap) encrypted in a different key (that's in the parent writecap but
not the parent readcap), or whether a dir looks like:

  name readcap [writecap]

and the whole writecap is encrypted in a key that is only in the parent
writecap.

random other questions:

Is the URI: format (textually) in the directory?  Or some binary format?

I also don't see a CLI command to take a writecap and return a readcap.

"tahoe get" on a directory didn't work:
  Error during GET: 302 Found

but I expected to get the directory contents.


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