On Fri, 20 Aug 2004 12:23:35 EDT, Barry Fitzgerald said: > An interesting cost benefit analysis of this would be to take the amount > of bandwidth increase if people used encrypted/authenticated > p.s. I'm not sure where to start to get valid numbers on this. Every > scenario I've been able to think of in the time it took to write this > e-mail has major methodological flaws. Estimating the overhead is pretty easy. As a straw man, take the size of the PGP signature on this message as a fairly fixed overhead for one style of "authenticated". For "encrypted", there's a good chance the message will actually end up *smaller*, because most crypto packages compress before signing, in order to (a) make it faster (as the compression is probably quicker than signing) and (b) more secure (the reason English text compresses so well is because there's lots of entropy - compressing first gets rid of a lot of the entropy). For another datapoint, consider the following DomainKey header I saw in a mail from an early adopter: DomainKey-Signature: a=rsa-sha1; s=mail; d=resistor.net; c=simple; q=; b=Hm PldyQdhZsXA12xUJ0oHscqlYYfF/E/H2T1MowOryfJnLfIIZGGUjYvSGMo2rFo That will also probably be a "usually fairly fixed size overhead" tag. The hard part is coming up with a good estimate of what % of spam will be properly authenticated once spammers start using the cached credentials already present on the PC in order to send out their spam....
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