Re: GPG fingerprints
also sprach Tim Haynes (on Mon, 17 Sep 2001 05:05:27PM +0100): Unless I'm well mistaken, of course... But I'd never trust a key whose fingerprint had turned up in public before. that's a little ridiculous, isn't it, given that i can use my gpg to view the fingerprint of your public key, which is, uh, public. you can safely post your fingerprint everywhere, but you have to do fingerprint verification - i have to read you mine - over the phone martin; (greetings from the heart of the sun.) \ echo mailto: !#^.*|tr * mailto:; [EMAIL PROTECTED] -- because light travels faster than sound, some people appear to be intelligent, until you hear them speak. pgpmlvSR4PScN.pgp Description: PGP signature
Re: GPG fingerprints
El lun, 17 de sep de 2001, a las 20:25 +0200, Martin decía que: also sprach Tim Haynes (on Mon, 17 Sep 2001 05:05:27PM +0100): Unless I'm well mistaken, of course... But I'd never trust a key whose fingerprint had turned up in public before. that's a little ridiculous, isn't it, given that i can use my gpg to view the fingerprint of your public key, which is, uh, public. you can safely post your fingerprint everywhere, but you have to do fingerprint verification - i have to read you mine - over the phone That's right, i use to show my fingerprint on my emails, of course if anyone want to trust my public key, he have to contact me in a more secure way than looking the signature of a single email. Looking lots of emails from me, some new, some old, could be a good way, a telephone call can be OK if you know my voice, and a mix of these things would be OK if you don't know me at all. Key-sharing in public events (like Linux conventions) it's also a good way of verifying public keys, you will meet the person, even you can ask him for his ID (car driving license or something like this), and also is a good way of making new friends, and talk a lot about linux ;-). Personal contact is (hopefully) the only real way to verify public keys, but the cost of been a man in the meddle fooling all the Internet, changing web logs of mail lists and database of every web crawler is so high that for the most common cases it's is sufficient with publishing your fingerprint on every email and your telephone number. Also use the common sense for this things, it is the best way of been real sure of the integrity of someone's public key. -- Yoda use the source, Luke! Alberto Cortés Martín | Ing. de Telecomunicaciones email: [EMAIL PROTECTED] | Universidad Carlos III tel: +34 91 450 09 85 | Madrid cel: 600 42 77 57 | Spain 1A8B 0FE6 2094 8E48 38A2 7785 03CD 07CD 6CA4 E242 pgpoVno2mBCdJ.pgp Description: PGP signature
Re: GPG fingerprints
Then, get in touch with me by some secure means and confirm that snip I think rather that secure it might be better to say using some other means of authentication. Authentication can mean a lot of things, with the method depending on the level of security required (a phone call to quote the fingerprint may be sufficient where you would recognise the persons voice and the data being transferred is not critical), but it definitely means through a different channel. I mention this because a friend/colleague use to send his GPG public key to people via email, and then placed his key fingerprint in his .sig, in the belief that this would enhance security (not to mention his geek-cred). A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of Applied Cryptography seemed to do the trick, and he sheepishly removed it. This same person is now contracting out his services as, among other things, a security expert. Caveat Emptor, Steve -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: GPG fingerprints
Hi, On Mon, 17 Sep 2001 19:42:05 +1000, Steve writes: I mention this because a friend/colleague use to send his GPG public key to people via email, and then placed his key fingerprint in his .sig, in the belief that this would enhance security (not to mention his geek-cred). A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of Applied Cryptography seemed to do the trick, and he sheepishly removed it. I think that many people put their fingerprint in their e-mail signature to exploit the Internet's archiving capability. If I e-mail you my public key, you should not pay attention to the fingerprint in the signature of that e-mail. However, you can go to dejanews.com, or the debian mailing list archives, or your own saved mail folder, and notice that every single message from me has the same GPG fingerprint, even the messages that are months or years old. From that, you can develop a degree of trust. --- Wade PS: Don't bother looking for the GPG fingerprint, I don't bother with GPG yet. -- /\ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \ / ASCII Ribbon Campaign| Wade Richards --- [EMAIL PROTECTED] X - NO HTML/RTF in e-mail | Fight SPAM! Join CAUCE. / \ - NO Word docs in e-mail | See http://www.cauce.org/ for details. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: GPG fingerprints
Wade == Wade Richards [EMAIL PROTECTED] writes: Wade I think that many people put their fingerprint in their e-mail Wade signature to exploit the Internet's archiving capability. If I Wade e-mail you my public key, you should not pay attention to the Wade fingerprint in the signature of that e-mail. However, you can go Wade to dejanews.com, or the debian mailing list archives, or your own Wade saved mail folder, and notice that every single message from me Wade has the same GPG fingerprint, even the messages that are months or Wade years old. From that, you can develop a degree of trust. I think the key (no pun intended) is to use multiple channels. My public key is available on a public keyserver. My fingerprints are pasted to all my mails which go to almost all mailing lists, and to all my newsgroup postings (and these, as you mentioned are available via http). So if someone wants to spoof my key, they would have to either - compromise groups.google.com, wwwkeys.pgp.net, lists.debian.org, various e-mail servers, etc - be very close to the person trying to get my key, so that they would be able to spoof traffic from these or - be very close to me and modify my outgoing messages and spoof network traffic when I try to verify that the keys/fingerprints have been sent correctly (which is probably pretty hard, since I have multiple network access points) On the other hand, if you send both fingerprint and gpg key via e-mail, there's just one service that needs to be attacked. Mind you, the best policy is to only fully trust keys that you can verify *in person*, or that can be verified via the web of trust, if you need to send/sign anything critical. (Speaking of which, is there anyone in the Waterloo (Canada) region who wants to sign my key? My key currently has 0 signatures (other than my self-sig).) -- Hubert Chan [EMAIL PROTECTED] - http://www.geocities.com/hubertchan/ PGP/GnuPG key: 1024D/71FDA37F Fingerprint: 6CC5 822D 2E55 494C 81DD 6F2C 6518 54DF 71FD A37F Key available at wwwkeys.pgp.net. Please encrypt *all* e-mail to me. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: GPG fingerprints
Wade Richards [EMAIL PROTECTED] writes: A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of Applied Cryptography seemed to do the trick, and he sheepishly removed it. I think that many people put their fingerprint in their e-mail signature to exploit the Internet's archiving capability. If I e-mail you my public key, you should not pay attention to the fingerprint in the signature of that e-mail. However, you can go to dejanews.com, or the debian mailing list archives, or your own saved mail folder, and notice that every single message from me has the same GPG fingerprint, even the messages that are months or years old. From that, you can develop a degree of trust. Yes. A zero-trust sense of trust. The whole point of having a fingerprint is to be able to compare it out of band - eg you send me your public key, I phone you back and you have to dig out the fingerprint which I compare from the public key, which is totally defeated if someone else can dig it out of deja/google! If you want to develop a sense of trust, then the most trust you can have is that `this poster' is the same as `that poster', because their messages both validate against the same key ID (*not* fingerprint). Unless I'm well mistaken, of course... But I'd never trust a key whose fingerprint had turned up in public before. ~Tim -- It's enough that I can see the morning |[EMAIL PROTECTED] In miracles much more than I can say|http://spodzone.org.uk/ It's enough to keep me still believing | In drifting hearts so far away | -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: GPG fingerprints
Tim Haynes wrote/napisa[a]/schrieb: Wade Richards [EMAIL PROTECTED] writes: A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of "Applied Cryptography" seemed to do the trick, and he sheepishly removed it. I think that many people put their fingerprint in their e-mail signature to exploit the Internet's archiving capability. If I e-mail you my public key, you should not pay attention to the fingerprint in the signature of that e-mail. However, you can go to dejanews.com, or the debian mailing list archives, or your own "saved mail" folder, and notice that every single message from me has the same GPG fingerprint, even the messages that are months or years old. From that, you can develop a degree of trust. Yes. A zero-trust sense of trust. The whole point of having a fingerprint is to be able to compare it out of band - eg you send me your public key, I phone you back and you have to dig out the fingerprint which I compare from the public key, which is totally defeated if someone else can dig it out of deja/google! WHAT!? Anyone who gets hold of a public key can check what fingerprint it has. There are public keyservers. There are public keys on the w3. Key fingerprint never was meant to be a secret. If you want to develop a sense of trust, then the most trust you can have is that `this poster' is the same as `that poster', because their messages both validate against the same key ID (*not* fingerprint). Unless I'm well mistaken, of course... But I'd never trust a key whose fingerprint had turned up in public before. I believe you are mistaken. Publishing fingerprint is a (weak) way to defeat MITM attacks. If someone constattly uses a key with a known fingerprint sudden change of fingerprint may may suggest MITM. Note: your method of comparing a fingerprint is weak. Fingerprint comaprition is a two way protocol. If Bob is to sign Alice's key he should read first group of fingerprint, then Alice should read the second, then Bob the third, etc. This ensures at least that Bob and Alice are talking about the same public key. Alex -- C _-=-_ H| Janusz A. Urbanowicz | ALEX3-RIPE | SF-F Framling | | * ; (_O : +-+ --+~| ! ~) ? | Pyn chc na Wschd, za Suez, gdzie jest dobrem kade zo | l_|/ A ~-=-~ O| Gdzie przykaza brak dziesiciu, a pi mona a po dno; | | -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: GPG fingerprints
also sprach Tim Haynes (on Mon, 17 Sep 2001 05:05:27PM +0100): Unless I'm well mistaken, of course... But I'd never trust a key whose fingerprint had turned up in public before. that's a little ridiculous, isn't it, given that i can use my gpg to view the fingerprint of your public key, which is, uh, public. you can safely post your fingerprint everywhere, but you have to do fingerprint verification - i have to read you mine - over the phone martin; (greetings from the heart of the sun.) \ echo mailto: !#^.*|tr * mailto:; net@madduck -- because light travels faster than sound, some people appear to be intelligent, until you hear them speak. PGP signature
Re: GPG fingerprints
Then, get in touch with me by some secure means and confirm that snip I think rather that secure it might be better to say using some other means of authentication. Authentication can mean a lot of things, with the method depending on the level of security required (a phone call to quote the fingerprint may be sufficient where you would recognise the persons voice and the data being transferred is not critical), but it definitely means through a different channel. I mention this because a friend/colleague use to send his GPG public key to people via email, and then placed his key fingerprint in his .sig, in the belief that this would enhance security (not to mention his geek-cred). A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of Applied Cryptography seemed to do the trick, and he sheepishly removed it. This same person is now contracting out his services as, among other things, a security expert. Caveat Emptor, Steve
Re: GPG fingerprints
Hi, On Mon, 17 Sep 2001 19:42:05 +1000, Steve writes: I mention this because a friend/colleague use to send his GPG public key to people via email, and then placed his key fingerprint in his .sig, in the belief that this would enhance security (not to mention his geek-cred). A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of Applied Cryptography seemed to do the trick, and he sheepishly removed it. I think that many people put their fingerprint in their e-mail signature to exploit the Internet's archiving capability. If I e-mail you my public key, you should not pay attention to the fingerprint in the signature of that e-mail. However, you can go to dejanews.com, or the debian mailing list archives, or your own saved mail folder, and notice that every single message from me has the same GPG fingerprint, even the messages that are months or years old. From that, you can develop a degree of trust. --- Wade PS: Don't bother looking for the GPG fingerprint, I don't bother with GPG yet. -- /\ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \ / ASCII Ribbon Campaign| Wade Richards --- [EMAIL PROTECTED] X - NO HTML/RTF in e-mail | Fight SPAM! Join CAUCE. / \ - NO Word docs in e-mail | See http://www.cauce.org/ for details.
Re: GPG fingerprints
Wade == Wade Richards [EMAIL PROTECTED] writes: Wade I think that many people put their fingerprint in their e-mail Wade signature to exploit the Internet's archiving capability. If I Wade e-mail you my public key, you should not pay attention to the Wade fingerprint in the signature of that e-mail. However, you can go Wade to dejanews.com, or the debian mailing list archives, or your own Wade saved mail folder, and notice that every single message from me Wade has the same GPG fingerprint, even the messages that are months or Wade years old. From that, you can develop a degree of trust. I think the key (no pun intended) is to use multiple channels. My public key is available on a public keyserver. My fingerprints are pasted to all my mails which go to almost all mailing lists, and to all my newsgroup postings (and these, as you mentioned are available via http). So if someone wants to spoof my key, they would have to either - compromise groups.google.com, wwwkeys.pgp.net, lists.debian.org, various e-mail servers, etc - be very close to the person trying to get my key, so that they would be able to spoof traffic from these or - be very close to me and modify my outgoing messages and spoof network traffic when I try to verify that the keys/fingerprints have been sent correctly (which is probably pretty hard, since I have multiple network access points) On the other hand, if you send both fingerprint and gpg key via e-mail, there's just one service that needs to be attacked. Mind you, the best policy is to only fully trust keys that you can verify *in person*, or that can be verified via the web of trust, if you need to send/sign anything critical. (Speaking of which, is there anyone in the Waterloo (Canada) region who wants to sign my key? My key currently has 0 signatures (other than my self-sig).) -- Hubert Chan [EMAIL PROTECTED] - http://www.geocities.com/hubertchan/ PGP/GnuPG key: 1024D/71FDA37F Fingerprint: 6CC5 822D 2E55 494C 81DD 6F2C 6518 54DF 71FD A37F Key available at wwwkeys.pgp.net. Please encrypt *all* e-mail to me.
Re: GPG fingerprints
Wade Richards [EMAIL PROTECTED] writes: A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of Applied Cryptography seemed to do the trick, and he sheepishly removed it. I think that many people put their fingerprint in their e-mail signature to exploit the Internet's archiving capability. If I e-mail you my public key, you should not pay attention to the fingerprint in the signature of that e-mail. However, you can go to dejanews.com, or the debian mailing list archives, or your own saved mail folder, and notice that every single message from me has the same GPG fingerprint, even the messages that are months or years old. From that, you can develop a degree of trust. Yes. A zero-trust sense of trust. The whole point of having a fingerprint is to be able to compare it out of band - eg you send me your public key, I phone you back and you have to dig out the fingerprint which I compare from the public key, which is totally defeated if someone else can dig it out of deja/google! If you want to develop a sense of trust, then the most trust you can have is that `this poster' is the same as `that poster', because their messages both validate against the same key ID (*not* fingerprint). Unless I'm well mistaken, of course... But I'd never trust a key whose fingerprint had turned up in public before. ~Tim -- It's enough that I can see the morning |[EMAIL PROTECTED] In miracles much more than I can say|http://spodzone.org.uk/ It's enough to keep me still believing | In drifting hearts so far away |
Re: GPG fingerprints
Tim Haynes wrote/napisał[a]/schrieb: Wade Richards [EMAIL PROTECTED] writes: A five minute explanation of the principle of a man-in-the-middle attack, followed by a swift bat upside the head with a copy of Applied Cryptography seemed to do the trick, and he sheepishly removed it. I think that many people put their fingerprint in their e-mail signature to exploit the Internet's archiving capability. If I e-mail you my public key, you should not pay attention to the fingerprint in the signature of that e-mail. However, you can go to dejanews.com, or the debian mailing list archives, or your own saved mail folder, and notice that every single message from me has the same GPG fingerprint, even the messages that are months or years old. From that, you can develop a degree of trust. Yes. A zero-trust sense of trust. The whole point of having a fingerprint is to be able to compare it out of band - eg you send me your public key, I phone you back and you have to dig out the fingerprint which I compare from the public key, which is totally defeated if someone else can dig it out of deja/google! WHAT!? Anyone who gets hold of a public key can check what fingerprint it has. There are public keyservers. There are public keys on the w3. Key fingerprint never was meant to be a secret. If you want to develop a sense of trust, then the most trust you can have is that `this poster' is the same as `that poster', because their messages both validate against the same key ID (*not* fingerprint). Unless I'm well mistaken, of course... But I'd never trust a key whose fingerprint had turned up in public before. I believe you are mistaken. Publishing fingerprint is a (weak) way to defeat MITM attacks. If someone constattly uses a key with a known fingerprint sudden change of fingerprint may may suggest MITM. Note: your method of comparing a fingerprint is weak. Fingerprint comaprition is a two way protocol. If Bob is to sign Alice's key he should read first group of fingerprint, then Alice should read the second, then Bob the third, etc. This ensures at least that Bob and Alice are talking about the same public key. Alex -- C _-=-_ H| Janusz A. Urbanowicz | ALEX3-RIPE | SF-F Framling | | * ; (_O : +-+ --+~| ! ~) ? | Płynąć chcę na Wschód, za Suez, gdzie jest dobrem każde zło | l_|/ A ~-=-~ O| Gdzie przykazań brak dziesięciu, a pić można aż po dno; | |
Re: GPG fingerprints
On Fri, Sep 14, 2001 at 09:02:53PM -0500, Warren Turkal wrote: Is it ok to have your GPG fingerprint publicly available? It is not only OK, but encouraged. If one can confirm that your fingerprint is valid (i.e. by calling you and saying is foo really your fingerprint?), then it's a safe bet that they have the right key, instead of a spoofed key. The GPG key fingerprint can be obtained from any public key by running 'gpg --fingerprint key_id', so you could run 'gpg --fingerprint [EMAIL PROTECTED]' and see the fingerprint for my key (assuming it's in your keyring). Then, get in touch with me by some secure means and confirm that it's D896 D80A C030 7F05 701E D535 62B5 4B8C 1140 4EC3 and you know that you have the right key. noah -- ___ | Web: http://web.morgul.net/~frodo/ | PGP Public Key: http://web.morgul.net/~frodo/mail.html PGP signature
Re: GPG fingerprints
On Fri, Sep 14, 2001 at 09:02:31PM -0500, Warren Turkal wrote: Is it ok to have your GPG fingerprint publicly available? Yes. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of unsubscribe. Trouble? Contact [EMAIL PROTECTED]
Re: GPG fingerprints
On Fri, Sep 14, 2001 at 09:02:31PM -0500, Warren Turkal wrote: Is it ok to have your GPG fingerprint publicly available? Yes.
