spf-discuss
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Re: the inevitability of SRS

2004-01-13 19:21:32
Meng Weng Wong wrote:

I would be happy to release a Mail::SRS::DBI subclass that performs the
rewrite to a 32 char HMAC plus 32 char DB key or something like that.

The point of publishing an SRS standard was so that an intermediary
could replace   A-B(_at_)C   with   A-D(_at_)E  instead of having to do
A-B-C-D(_at_)E(_dot_)  If the whole thing gets shoved into a DB there's no need 
for
a standard syntax with delimiters and whatnot.

I'm not sure that you can do this. In particular, E cannot know whether the previous entry had the correct hash or not. I think that the only solution is to use a database to perform the mapping. I'd be inclined to HMAC the sender using a secret key. Then just send the message on with bounce-<hash> as the sender. You need to store the mapping from hash to sender in a database, along with some timeouts. I'm not entirely certain why we should use an HMAC rather than a hash, but it seems to provide a little extra security for very little extra cost.

Philip

--
Philip Gladstone
* Check out the live pondcam at http://pond.gladstonefamily.net

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