Re: [openpgp] New fingerprint: to v5 or not to v5
Peter Gutmann <pgut001@cs.auckland.ac.nz> Wed, 07 October 2015 14:03 UTC
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From: Peter Gutmann <pgut001@cs.auckland.ac.nz>
To: Werner Koch <wk@gnupg.org>
Thread-Topic: [openpgp] New fingerprint: to v5 or not to v5
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Date: Wed, 07 Oct 2015 14:02:17 +0000
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References: <878u84zy4r.fsf@vigenere.g10code.de> <87fv1xxe5w.fsf@alice.fifthhorseman.net> <87r3lgcup8.fsf@vigenere.g10code.de> <CACsn0c=-LKagSqTbgOV1W4Gu4u-f6vpVq82-nWSLGogjoeFKeg@mail.gmail.com> <CAMm+LwjeKDKnN2ZAisbKhWVS4kwCEm_VvcZ1MtftYzEJQpGdhg@mail.gmail.com> <87y4fi5wa9.fsf@vigenere.g10code.de> <9A043F3CF02CD34C8E74AC1594475C73F4B278ED@uxcn10-5.UoA.auckland.ac.nz> <8737xp5z45.fsf@vigenere.g10code.de> <9A043F3CF02CD34C8E74AC1594475C73F4B279C6@uxcn10-5.UoA.auckland.ac.nz>, <87fv1o4e9n.fsf@vigenere.g10code.de>
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Cc: Watson Ladd <watsonbladd@gmail.com>, Phillip Hallam-Baker <phill@hallambaker.com>, Daniel Kahn Gillmor <dkg@fifthhorseman.net>, IETF OpenPGP <openpgp@ietf.org>
Subject: Re: [openpgp] New fingerprint: to v5 or not to v5
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Werner Koch <wk@gnupg.org> writes: >That explicit ID sounds pretty much like a issuer+serialno or one of the >other X.509 methods to identify a key. It is not a fingerprint as we know it >and it can't be used as a secure identification of the key. It works quite well as a unique identifier for a key. The problem here is that PGP makes the same mistake that's made in things like credit cards and SSNs, where you've got a magic value that's supposed to be both a unique identifier (public) and an authentication/authorisation value (private). X.509 handles this by having two distinct things, a unique identifier (subjectKeyIdentifier) to identify a key, and a fingerprint (hash of the cert) to verify its integrity or whatever it is you want to do with it. PGP in contrast confuses the two, so you have a supposedly unique identifier that hashes in a mutable value (the time) but then doesn't hash in other important information like the user ID associated with the key. So it doesn't work very well either as an identifier or as an integrity-check value. The fix would be to have two distinct values, a unique identifier (64 or 128 bits of whatever) to uniquely identify a key, and then a fingerprint that covers the key, subkey(s), user ID(s), attributes, and whatnot, to check that you've got what you were expecting to get. >Lost key? The key is present somewhere on the keyring but the date has changed, so you can't locate it by key ID any more because the date hashed into the other bits and pieces changes the key ID. Peter.
- [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 vedaal
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 ianG
- Re: [openpgp] New fingerprint: to v5 or not to v5 Simon Josefsson
- Re: [openpgp] New fingerprint: to v5 or not to v5 Daniel Kahn Gillmor
- Re: [openpgp] New fingerprint: to v5 or not to v5 ianG
- Re: [openpgp] New fingerprint: to v5 or not to v5 Daniel A. Nagy
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: which hash algo (w… Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Watson Ladd
- Re: [openpgp] New fingerprint: to v5 or not to v5 Phillip Hallam-Baker
- Re: [openpgp] New fingerprint: which hash algo (w… Tom Ritter
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Mark D. Baushke
- Re: [openpgp] New fingerprint: to v5 or not to v5 Peter Gutmann
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Peter Gutmann
- Re: [openpgp] New fingerprint: to v5 or not to v5 ianG
- Re: [openpgp] New fingerprint: to v5 or not to v5 ianG
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: which hash algo (w… Simon Josefsson
- Re: [openpgp] New fingerprint: to v5 or not to v5 Peter Gutmann
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Peter Gutmann
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Peter Gutmann
- Re: [openpgp] New fingerprint: which hash algo ianG
- Re: [openpgp] New fingerprint: which hash algo vedaal
- Re: [openpgp] New fingerprint: which hash algo Steve Pointer
- Re: [openpgp] New fingerprint: which hash algo Alessandro Barenghi
- Re: [openpgp] New fingerprint: which hash algo Robert J. Hansen
- Re: [openpgp] New fingerprint: to v5 or not to v5 Daniel Kahn Gillmor
- Re: [openpgp] New fingerprint: to v5 or not to v5 Peter Gutmann
- Re: [openpgp] New fingerprint: to v5 or not to v5 Jonathan McDowell
- Re: [openpgp] New fingerprint: to v5 or not to v5 Nicholas Cole
- Re: [openpgp] New fingerprint: to v5 or not to v5 Vincent Breitmoser
- Re: [openpgp] New fingerprint: which hash algo Daniel A. Nagy
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: to v5 or not to v5 Peter Gutmann
- Re: [openpgp] New fingerprint: to v5 or not to v5 Watson Ladd
- Re: [openpgp] New fingerprint: to v5 or not to v5 Werner Koch
- Re: [openpgp] New fingerprint: which hash algo Phillip Hallam-Baker
- Re: [openpgp] New fingerprint: which hash algo ianG
- Re: [openpgp] New fingerprint: which hash algo Daniel Kahn Gillmor
- Re: [openpgp] New fingerprint: which hash algo Phillip Hallam-Baker