Re: Evil PGP sigs thread must die. was Re: Stop it with putting your e-mail body in my MUA OT
On Wed, 10 Jul 2002, Jordyn A. Buchanan wrote:
On 7/10/02 3:01 PM, "Andy Dills" <andy@xecu.net> wrote:
Ah, and that's where the arrogance comment came from. You assume that the members of nanog care. I'm not trying to call you an arrogant person, and I recognize that you're not being blatantly arrogant, it's more of a passive assumption. The passive assumption is that your words are important enough that somebody might want to verify them. So, does EVERY email need to be pgp signed?
If you don't reliably sign your e-mails, it becomes very easy for someone to send a spoofed message without a signature and have people believe it is authentic. If you do reliably sign your e-mails, then others may realize that something is awry when an unsigned message is sent out. Even if the signatures are rarely checked, consistency of signing is a useful function by creating an expectation of trusted communications.
Uhm, one HUGE problem with that. If people judge authenticity based on the simple fact that a message is signed, that's just as useless. Why wouldn't the spoofed email be signed with somebody else's key, to make it past all those people who merely check to see if it's signed? The _only_ way to verify authenticity is to check the signature. By signing every single email sent, you endanger yourself by allowing your recipients to judge the authenticity of your emails simply by the existence of a pgp signature. Therefore, you should only sign emails that contain information important enough that verification is necessary, otherwise nobody will check. Andy xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Andy Dills 301-682-9972 Xecunet, LLC www.xecu.net xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Dialup * Webhosting * E-Commerce * High-Speed Access
Which is why the "web of trust" exists. And why people do keysignings at NANOG events. And why, at least on my mail client, the signature shows the email address of its owner. If Scott spoofs and email from me and signs it with his key, people will notice. -C
If people judge authenticity based on the simple fact that a message is signed, that's just as useless. Why wouldn't the spoofed email be signed with somebody else's key, to make it past all those people who merely check to see if it's signed?
The _only_ way to verify authenticity is to check the signature. By signing every single email sent, you endanger yourself by allowing your recipients to judge the authenticity of your emails simply by the existence of a pgp signature.
Therefore, you should only sign emails that contain information important enough that verification is necessary, otherwise nobody will check.
Andy
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Andy Dills 301-682-9972 Xecunet, LLC www.xecu.net xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Dialup * Webhosting * E-Commerce * High-Speed Access
At 3:15 PM -0400 2002/07/10, Andy Dills wrote:
If people judge authenticity based on the simple fact that a message is signed, that's just as useless. Why wouldn't the spoofed email be signed with somebody else's key, to make it past all those people who merely check to see if it's signed?
The _only_ way to verify authenticity is to check the signature.
True enough. But you do significantly raise the bar. It's like putting a deadbolt lock on your front door -- maybe it's locked, and maybe it's not. But it's very presence will tend to deter a certain percentage of attackers. However, even if the door is locked, we all know that a sufficiently motivated attacker can get past *ANY* lock. If they can't break the lock itself, they break the door. If they can't break the door, they break a window. If they can't break a window, then they break a wall. But it is a pretty good deterrent for people who just walk around twiddling knobs.
Therefore, you should only sign emails that contain information important enough that verification is necessary, otherwise nobody will check.
Nope. The only way to make this work is to sign all messages, and all messages that are not signed are automatically suspect. Indeed, even signed messages are at least somewhat suspect, and should always have the signature validated -- modern encryption/keyring management programs should make this fairly easy to make automatically happen by default. -- Brad Knowles, <brad.knowles@skynet.be> "They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety." -Benjamin Franklin, Historical Review of Pennsylvania.
oh. my. god. just when i thought that the subject line could not get any longer in this thread. it's just one of my pointless pet peeves... deeann m.m. mikula director of operations telerama public access internet http://www.telerama.com * 412.688.3200
participants (4)
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deeann mikula