[tahoe-dev] Verifying file contents

[Shawn Willden]

Is there an easy/inexpensive way to check that a local file matches a remote 
(immutable) file?

I could extract the Tahoe code that calculates the key from the local file, 
given the current convergence secret, and then compare that with the key in 
the URI.  Or perhaps modify Tahoe to expose a "key calculation" service 
through the web API.

Another thing I could do is upload the local file as an immutable file.  If 
the file is already in the grid, this shouldn't take very long, and the 
returned URI should match.  But if the local file doesn't match the remote 
file, the local file will be uploaded to the grid, which I don't really want.

Is there a way (through the web API) to "fake" a PUT?  That is, do everything 
except actually communicate with storage servers?

A problem with all of these methods is that they break if the convergence key 
doesn't match, but I suppose that's a feature, not a bug.

Thanks,

	Shawn