when the confwiz configures a node (i.e. typically once on mac, once per
install on windows) in addition to writing the root_dir.cap retrieved from
the native_client backend into a config file, it additionally writes a hash
thereof into the 'convergence' config file.
this causes uploads from this node to use a consistent 'convergence' hashing
value matching any other nodes with the same configured root_dir, i.e. for
the most part other systems installed and configured on the same account.
This removes the guess-partial-information attack vector, and reduces
the amount of overhead that we consume with each file. It also introduces
a forwards-compability break: older versions of the code (before the
previous download-time "make hashes optional" patch) will be unable
to read files uploaded by this version, as they will complain about the
missing hashes. This patch is experimental, and is being pushed into
trunk to obtain test coverage. We may undo it before releasing 1.0.
Now upload or encode methods take a required argument named "convergence" which can be either None, indicating no convergent encryption at all, or a string, which is the "added secret" to be mixed in to the content hash key. If you want traditional convergent encryption behavior, set the added secret to be the empty string.
This patch also renames "content hash key" to "convergent encryption" in a argument names and variable names. (A different and larger renaming is needed in order to clarify that Tahoe supports immutable files which are not encrypted content-hash-key a.k.a. convergent encryption.)
This patch also changes a few unit tests to use non-convergent encryption, because it doesn't matter for what they are testing and non-convergent encryption is slightly faster.
This removes the guess-partial-information attack vector, and reduces
the amount of overhead that we consume with each file. It also introduces
a forwards-compability break: older versions of the code (before the
previous download-time "make hashes optional" patch) will be unable
to read files uploaded by this version, as they will complain about the
missing hashes. This patch is experimental, and is being pushed into
trunk to obtain test coverage. We may undo it before releasing 1.0.
Removing the plaintext hashes can help with the guess-partial-information
attack. This does not affect compatibility, but if and when we actually
remove any hashes from the share, that will introduce a
forwards-compatibility break: tahoe-0.9 will not be able to read such files.
this changes the confwiz to have a look and feel much more consistent
with that of the innosetup installer it is launched within the context
of. this applies, naturally, primarily to windows.
added a test for the simple mkdir-p hack I added yesterday
checks that mkdir-p can create a directory hierarchy, and that resubmitting
a request for the same path yields the existing dir's uri
this adds a t=mkdir-p call to directories (accessed by their uri as
/uri/<URI>?t=mkdir=p&path=/some/path) which returns the uri for a
directory at a specified path before the given uri, regardless of
whether the directory exists or whether intermediate directories
need to be created to satisfy the request.
this is used by the migration code in MV to optimise the work of
path traversal which was other wise done on every file PUT
