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Alice updates her OpenPGP key yearly. Bob updates his copy using: gpg2 --refresh-keys

Mallory ensures that Bob uses her keyserver, which offers her own key, which

  1. is sharing the 32-bit "short" Key ID with Alice
  2. is sharing the 64-bit "long" Key ID with Alice
  3. is sharing the entire 160-bit SHA1 fingerprint with Alice

In which of the 3 cases will Bob download, store or even subsequently use Mallory's key?


  • Are you aware of the difference between collisions and preimages? – forest Mar 30 at 1:10
  • @forest I believe so. Is there anything in my question that depends on it? – anx Mar 30 at 9:11
  • Yes. If you are worried about someone creating two keys, one malicious and one not, just so they can trigger a fingerprint collision later, then there is a risk. If you are worried about someone not involved in creating the original key finding a preimage to impersonate the original key, you have much, much less to worry about. – forest Mar 30 at 9:21
  • Wait, is it unreasonable to expect that the refresh operation will always discard unrelated data? – anx Mar 30 at 11:51
  • What do you mean by discarding unrelated data? – forest Mar 30 at 22:48

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