[tahoe-dev] updates to chk.jpg

[zooko]

There is a nice work of art on the wiki, in the medium of "digital  
photo of whiteboard":

http://allmydata.org/trac/tahoe/attachment/wiki/Doc/chk.jpg

As part of the ticket to update docs for v0.6 release (ticket #135),  
I examined it, and there are a few things that are out of date.


First, the question mark next to the blue arrow from encryption key  
to storage index should be erased, because the storage index is  
always generated from the encryption key now.

Also we should show a light green hollow-headed arrow in the reverse  
direction, from storage index to encryption key, because we now rely  
on the storage index to detect a corrupted encryption key (e.g. due  
to user error in transcription).  (See ticket #86)

Also the storage index itself is now 16 B, not 32 B as the diagram  
still shows.

Also the storage index is no longer actually included in the CHK URI  
-- it is generated from the encryption key when needed.

Second, we should show an optional blue arrow from data to encryption  
key, which shows the optional convergent encryption.


I don't have a good X server handy with which to run Gimp, but  
hopefully someone out there who is artistic will make these changes  
and post an updated chk.jpg to the wiki.  If not I'll install Gimp on  
my Mac using XDarwin...


Regards,

Zooko

tickets mentioned in this e-mail:

http://allmydata.org/trac/tahoe/ticket/135
http://allmydata.org/trac/tahoe/ticket/86