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Cryptography Dispatches: Hello World, and OpenPGP Is Broken

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Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#21

Post by mikekchar »

tptacek wrote: post #16
mikekchar wrote: post #14

Earlier quoted context omitted.

I think we need to rely on this at some point, though. If my friend Alice introduces her friend Bob to me, that's my only way of determining that when Alice is talking about Bob, it's this Bob and not a different Bob. I actually don't think there is a problem with the concept of a web of trust per se. It's a fact of life. I think that the software doesn't help you use it appropriately. Even if Alice says that a perso…

The kernel of the conceptual problem with this web-of-trust feature is in another Filippo post[1]: when I sign someone's else's key, it is difficult (in practice: impossible) to really know the provenance of that key. The signer could have gotten the key from a keyserver (in which case you now transitively trust the keyserver). Or they could have gotten it from a random email saying "this is my new key". You don't kn…

I'm definitely not arguing against that. I think keyservers are one of the worst things to ever happen. PGP's implementation of the web of trust is hugely flawed. I'm saying the concept is still incredibly useful. I get frustrated when I see suggestions that we should abandon the notion signing other people's keys because users can't be trusted to do it properly.

I think the author of the article you link to is mostly right. Long term keys don't make much sense most of the time. A key that's signed by a million people is useless. I only care that it's singed by the people who are relevant in the context for which I'm using it. Relationships change too. If I've got a key from level 1 support to a level 2 support person, I can't trust 6 months later that the level 2 support person still works at the company. You need to have a context to describe the link in order to understand it. PGP (and by extension GPG) are absolutely horrible in that regard.

I find it ironic that the author says that the best way to reach them is by their Whisper number. This is what frustrates me. We exchange "horribly flawed implementation" for a central trust broker -- who may or may not be trust worthy.

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#22

Post by cyphar »

tptacek wrote: post #16
mikekchar wrote: post #14

Earlier quoted context omitted.

I think we need to rely on this at some point, though. If my friend Alice introduces her friend Bob to me, that's my only way of determining that when Alice is talking about Bob, it's this Bob and not a different Bob. I actually don't think there is a problem with the concept of a web of trust per se. It's a fact of life. I think that the software doesn't help you use it appropriately. Even if Alice says that a perso…

The kernel of the conceptual problem with this web-of-trust feature is in another Filippo post[1]: when I sign someone's else's key, it is difficult (in practice: impossible) to really know the provenance of that key. The signer could have gotten the key from a keyserver (in which case you now transitively trust the keyserver). Or they could have gotten it from a random email saying "this is my new key". You don't kn…

If only distributed signatures included trust levels -- then you could at least attempt something like that. Though unfortunately trust levels are themselves incredibly coarse and subjectively determined (does "I trust fully" mean "I checked 6 forms of government ID" or "I know this person by their handle"?).

To be honest, I think Keybase has the only workable solution to this problem for modern online personalities -- tie it to directly to your other identities online such that you would need to break into many accounts in order to fake someone's identity. And individual users can decide for themselves what threshold of trust they have for someone.

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#23

Post by rrggrr »

mbrumlow wrote: post #5

Can we stop saying that pgp is busted and just talk about how the keyservers are the problem with how people decides to exchange keys ? I don't use key servers. So when I get an encrypted message from my friend I have no issues. Allowing a third party such as a key server to play some role in veifiing the authenticity of a key is basically broken from tht start, and has nothing to do with pgp it's self.

No, it's a choice. It's "pretty good" privacy to exchange encrypted comms via Keybase vs. plaintext. And, yes, if it were existentially important than direct key exchange would be better.

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#24

Post by na85 »

tptacek wrote: post #15
mbrumlow wrote: post #12

Earlier quoted context omitted.

Then there is no need to say OpenPGP is broken. Once you hand off the validation to a 3rd party that does nothing to validate other than a voting system of other people then you are done. You basically put your PGP keys on reddit and decided the key is valid because it made it to the front page. PGP may be many things, but it is not broken, and saying so is blaming the tool for a obviously bad use of it.

It is obviously broken. Your objection is that it isn't comprehensively or irretrievably broken, and while I disagree, I don't have to litigate that, because the narrower sense of the word carries the article. I don't think you can fall back on this being an "obviously bad use of the tool", by the way, since it's a pretty core use of OpenPGP. I don't use keyservers either (or didn't, when I still used PGP, which I ac…

What do you use for secure communication in lieu of openpgp?

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#25

Post by tptacek »

na85 wrote: post #24
tptacek wrote: post #15

Earlier quoted context omitted.

It is obviously broken. Your objection is that it isn't comprehensively or irretrievably broken, and while I disagree, I don't have to litigate that, because the narrower sense of the word carries the article. I don't think you can fall back on this being an "obviously bad use of the tool", by the way, since it's a pretty core use of OpenPGP. I don't use keyservers either (or didn't, when I still used PGP, which I ac…

What do you use for secure communication in lieu of openpgp?

Signal or Wire, magic-wormhole. The obvious stuff.

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#26

Post by mbrumlow »

tptacek wrote: post #25
na85 wrote: post #24

Earlier quoted context omitted.

What do you use for secure communication in lieu of openpgp?

Signal or Wire, magic-wormhole. The obvious stuff.

And yet all of those bypass the hard part of validating the sender. These again trust the service.

PGP is more than simply encryption. It provides a means of trusted identity.

End to End encryption is pointless if you have no way to validate that a message came sender. Relying on automated systems for key exchange will always suffer from this problem.

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#27

Post by inflatableDodo »

tptacek wrote: post #6

To be clear: this is a subhed from Filippo's email newsletter (which you should subscribe to), relating a news item about the ridiculous SKS/GnuPG-key-handling fiasco from last week; it is not a comprehensive summary of all the ways in which OpenPGP is broken, despite the title.

>it is not a comprehensive summary of all the ways in which OpenPGP is broken

Is there a comprehensive summary anywhere?

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#28

Post by yarrel »

edoceo wrote: post #17
mbrumlow wrote: post #5

Can we stop saying that pgp is busted and just talk about how the keyservers are the problem with how people decides to exchange keys ? I don't use key servers. So when I get an encrypted message from my friend I have no issues. Allowing a third party such as a key server to play some role in veifiing the authenticity of a key is basically broken from tht start, and has nothing to do with pgp it's self.

Isn't keybase.io trying to solve this?

They decided to bolt on sending cryptocurrency to people they haven't KYC/AML'd instead.

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#29

Post by yarrel »

tptacek wrote: post #6

To be clear: this is a subhed from Filippo's email newsletter (which you should subscribe to), relating a news item about the ridiculous SKS/GnuPG-key-handling fiasco from last week; it is not a comprehensive summary of all the ways in which OpenPGP is broken, despite the title.

I'm not subscribing based on this particular bit of rehashing. I can keep up with the "hey just stalk women using Signal, the EFF said so" crowd on HN just fine.

Re: Cryptography Dispatches: Hello World, and OpenPGP Is Broken

#30

Post by tptacek »

mbrumlow wrote: post #26
tptacek wrote: post #25

Earlier quoted context omitted.

Signal or Wire, magic-wormhole. The obvious stuff.

And yet all of those bypass the hard part of validating the sender. These again trust the service. PGP is more than simply encryption. It provides a means of trusted identity. End to End encryption is pointless if you have no way to validate that a message came sender. Relying on automated systems for key exchange will always suffer from this problem.

That "means of trusted identity" doesn't work, to a first approximation nobody even attempts to use it, of those that do, a vanishing fraction "succeed", and their reward for doing so is the adoption of rickety 1990s encryption. Among practicing cryptography engineers, "web of trust" is a punch line, not a goal.

The lucky PGP users stick to the command line, which is so clunky that they'll use it rarely. The less fortunate will use PGP email clients which are so poorly thought out that they just last year managed to exfiltrate plaintext to attackers.

Signal use in the real world dwarfs that of OpenPGP; it's almost certainly many orders of magnitude.

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