key-signing and stolen subkeys

[Atom 'Smasher']

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On Sun, 23 May 2004, David Shaw wrote:

> Mallory doesn't issue the challenge.  The person who Mallory wants to
> sign his or Alice's key issues the challenge.
>
> A challenge is of no use to someone else since Mallory doesn't get to
> issue it in the first place.
======================

i think mallory could trick someone into using his challenge. mallory is
adept at the fine art of social engineering.

~you~ know better than to accept a cooked challenge; alice does not.
mallory agrees to a challenge with you and expects you to sign it send it
to him. at the same keysigning party, mallory offers the same challenge to
alice, who is new to pgp and accepts mallory's non-random challenge.

mallory can present your signing key to alice and/or alice's signing key
to you, and he can "prove" to both of you that he has the corresponding
secret keys. both you and alice could be fooled into signing a bogus
key... if the only thing that's signed is the challenge. this attack can
be defeated by not accepting (or generating) a signed challenge unless it
explains what that challenge is being used for, and by whom.


 	...atom

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Comment: What is this gibberish?  -  http://atom.smasher.org/links/#digital_signatures

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