[Dovecot] SIS Implementation

[Timo Sirainen]

On Fri, 2009-08-14 at 13:54 -0700, Daniel L. Miller wrote:
> Timo Sirainen wrote:
> > Step 4) Figure out if base64-encoded attachments can be decoded in a way
> > that allows re-encoding them back to the exact original encoding. If so,
> > save the attachment decoded and add the necessary encoding info the dbox
> > metadata.
> >
> > Or perhaps just store them compressed. How much of a difference is there
> > between storing decoded data vs. compressed base64 encoded data?
> >
> >   
> Do we need a new parameter in dovecot.conf?  "SIS_Location"?
> 
> Why is the base64 sum needed of the SHA256?  Isn't the SHA256 unique enough?

I'm not sure if you're mixing two things or replying to wrong mail
or.. :) Anyway:

In previous mail I said take base64 of SHA256 for the filename. Because
all characters aren't valid in filenames.

Here I'm just thinking about dropping base64 encoding of attachments and
storing them decoded, so 25% of disk space could be used.

> If the attachments are already compressed via zip or some such, would 
> further encoding just add processing time without any storage benefit?

Further compression of attached binaries wouldn't of course benefit
anything. But if the compressed attachment was stored as base64 (since
that's how they're sent via email..) compressing that could get it close
to original size.
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