From: Uwe Brauer <oub@mat.ucm.es>
To: info-gnus-english@gnu.org
Subject: Re: Trust and public keys
Date: Wed, 18 Nov 2015 15:04:10 +0000 [thread overview]
Message-ID: <87fv03mjrp.fsf@mat.ucm.es> (raw)
In-Reply-To: <87k2phprwq.fsf@informationelle-selbstbestimmung-im-internet.de>
> On 2015-11-15, at 21:07, Uwe Brauer wrote:
> That came out wrong, then. Part of my problem would be to figure
> out the “real” e-mail address of “Ed Snowden”. If you registered
> the fresh e-mail address “ed.snowden@gmail.com” and uploaded a
> matching key to usual keyservers, then I might fall for that. No
> special attack skills required.
Correct but this applies to smime and gpg.
> I don’t know too much about CAs that issue e-mail certificates for
> free. However, based on your description of Comodo I guess that you
> could also obtain an S/MIME certificate in the above case (for
> ed.snowden@gmail.com after registering that address). So the
> “trust” built into S/MIME seems worthless.
For class 1 certificate yes, for class 2 not, there you have to show up
(and to pay.)
> For me as malicious CA (or intruder into a CA) there is no reason to
> steal the private key as I could generate a certificate with
> matching private key in your name for your e-mail address, which is
> “trusted”. Then I could send signed e-mails in your name. That
> alone might get you into trouble, but you might receive responses
> that alert you about some ongoing attack. If I was a powerful
> attacker, able to replace e-mails on the way, I could additionally
> re-encrypt (modified) responses to your real certificate (or drop
> messages entirely), and you would never know I was there.
> If I cannot replace e-mails on the way, I can still send “trusted”
> signed e-mails in your name and tell the recipients to switch to
> different e-mail addresses with “trusted” certificates. Then,
> again, I can re-encrypt responses to your real certificate and
> e-mail address.
But in all of these scenarios you need to hack the email account. It is
not sufficent just to use a linux smptmail server and manipulate the
form field. You also have to intercept the reply.
I don't see much of a difference between
- the pgp scenario: to place a falsified pgp key on a server
- the smime scenario: to crack a smime certificate by breaching a
CA (which is more difficult that placing a falsified pgp key).
Best
Uwe
Again the question was is smime easier to use.
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next prev parent reply other threads:[~2015-11-18 15:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-08 16:15 S/MIME with OpenSSL? Jens Lechtenboerger
2015-11-10 16:42 ` Uwe Brauer
2015-11-10 21:41 ` Adam Sjøgren
2015-11-11 9:38 ` Uwe Brauer
2015-11-11 16:12 ` Adam Sjøgren
2015-11-12 9:31 ` Uwe Brauer
2015-11-12 15:31 ` Adam Sjøgren
2015-11-13 18:55 ` Uwe Brauer
2015-11-14 15:37 ` Trust and public keys (was: S/MIME with OpenSSL?) Jens Lechtenboerger
2015-11-15 21:07 ` Trust and public keys Uwe Brauer
2015-11-16 21:15 ` Jens Lechtenboerger
2015-11-18 15:04 ` Uwe Brauer [this message]
2015-11-19 17:05 ` Jens Lechtenboerger
2015-11-22 18:09 ` [smime and gpg] (was: Trust and public keys) Uwe Brauer
2015-11-16 11:32 ` Trust and public keys Uwe Brauer
2015-11-12 19:20 ` S/MIME with OpenSSL? Peter Münster
2015-11-13 18:21 ` Uwe Brauer
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