[Cryptography] Attacks on PGP (and allegedly S/MIME)

[Stephen Farrell]

Hiya,

On 05/17/2018 06:44 AM, Peter Gutmann wrote:
> Just to confound things even further, the "encrypt everything"
> approach makes this even worse.  If you've only got sensitive,
> valuable email traffic encrypted then you can afford to be careful
> with it, refuse to auto-render HTML, follow links, and so on.
> However, if every piece of HTML-encrusted gunk that turns up is also
> encrypted, you can no longer tell whether it's something you want to
> isolate or not, and if you do isolate everything users will switch to
> a different mailer that "works", in the sense that it displays the
> HTML-encrusted gunk as intended.

I have two reasons to disagree with the above.

1) I don't believe anyone can realistically process things they
need to be careful with differently unless they're forced to do
that (e.g. via regulation, or some technical feature of the thing
being dealt-with). I reckon everyone's drowning in so much mail
that that's not really feasible as "important, must encrypt" is
highly unlikely to be something a user would realise for a mail
just before sending.

2) I do get a lot of mail, don't render HTML etc. and can work
just fine. That's a teeny pain every now and then when I have to
save and use munpack, but that's <1/month I figure. I'm very
sure I ignore a lot of HTML-only encoded attachment crap, but
I don't seem to feel any sadness resulting:-)

So I guess we disagree - in my experience "what's important" isn't
easy to treat specially but "what's broken that needs handling" is
more tractable. If I'm right then encrypting doesn't make this
situation worse for the reasons stated. (Encrypting by default,
more does clearly increase the risk related to other aspects of
these bugs.)

Cheers,
S.
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