Timeline for Is PGP secure against a rogue keyserver?
Current License: CC BY-SA 3.0
9 events
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| Aug 23, 2013 at 14:02 | comment | added | Tom Leek | @Chaos_99: that's the whole point: you do not sign keys which you obtain from key servers. You sign only keys that you could verify to belong to the designated owner through "some other way" (namely, you met the guy in person). Key servers are there just to propagate the results (signed keys), but not to bootstrap the system. | |
| Aug 23, 2013 at 13:47 | comment | added | AJ Henderson | @Chaos_99 - you don't trust someone named Bob, you trust a public key that you obtained from Bob via a mechanism you trust. You store that key in a place on your system configured as a trusted root. Yes, you have to obtain it securely, but it doesn't have to be traced back to your key, it can be traced back to Bob's key which you hold the public key for. Names on keys are more or less just for human readability and the ability to look up which key to try to verify against (so you don't have to try them all.) | |
| Aug 23, 2013 at 13:34 | comment | added | Chaos_99 | @AJ My Problem is that any key could say it's trusted by Bob. (= I can forge a key with a signature that says "Bob" and even has Bob's key-ID.) But to cryptographically verify that it indeed is trusted by the exact same Bob i already trust, I need Bob's unmodified public key, either from local storage or secure side channel. | |
| Aug 23, 2013 at 13:23 | comment | added | AJ Henderson | @Chaos_99 - it doesn't necessarily have to be traced back to your private key, just to a key in your trusted key ring. I may trust Bob's certificate but not sign it. Even if I don't sign it, if I see that Charlie is signed by Bob, I know that Bob is a trusted root, so I can trust Charlie. If Charlie then trusts Daniel, I can trust Daniel since Charlie trusts Daniel, though I may decide to put a little less confidence in it since I don't know how trustworthy Charlie is. | |
| Aug 23, 2013 at 12:02 | comment | added | Chaos_99 | See my comment on AJs answer. If you need follow the chain of trust back to your key, you would have to have signed at least one other key in the past (or else there would be no chain). For signing this key, you would had to obtain it. But if you can't trust the keyserver to deliver the right key, you MUST have gotten the key to sign via another (secure) channel. | |
| Aug 23, 2013 at 11:55 | comment | added | Tom Leek | See the "Web of Trust". You verify a signature on something relatively to a known public key. You have to start with a known public key, i.e. yours. Each verified signature on a public key then gives you some kind of guarantee on the veracity of that key, allowing you to proceed. | |
| Aug 23, 2013 at 9:46 | comment | added | Chaos_99 | You said "A PGP public key might be trusted, or not, depending on the signatures by other key bearers that you will find on that key." The question was: how can I decide, if the signatures might be all faked? | |
| Aug 21, 2013 at 21:43 | history | edited | Iszi | CC BY-SA 3.0 |
added 56 characters in body
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| Aug 21, 2013 at 15:51 | history | answered | Tom Leek | CC BY-SA 3.0 |