Fake PGP Keys For Crypto Developers Found 110
IamTheRealMike (537420) writes "In recent months fake PGP keys have been found for at least two developers on well known crypto projects: Erinn Clark, a Tor developer and Gavin Andresen, the maintainer of Bitcoin. In both cases, these PGP keys are used to sign the downloads for popular pieces of crypto software. PGP keys are supposed to be verified through the web of trust, but in practice it's very hard to find a trust path between two strangers on the internet: one reply to Erinn's mail stated that despite there being 30 signatures [attached to] her key, [the respondent] couldn't find any trust paths to her. It's also very unclear whether anyone would notice a key substitution attack like this. This leaves three questions: who is doing this, why, and what can be done about it? An obvious candidate would be intelligence agencies, who may be trying to serve certain people with backdoored binaries via their QUANTUMTHEORY man-in-the-middle system. As to what can be done about it, switching from PGP to X.509 code signing would be an obvious candidate. Both Mac and Windows support it, obtaining a forged certificate is much harder than simply uploading a fake PGP key, and whilst X.509 certs can be issued in secret until Google's Certificate Transparency system is fully deployed, finding one would be strong evidence that an issuing CA had been compromised: something that seems plausible but for which we currently lack any evidence. Additionally, bad certificates can be revoked when found whereas beyond making blog posts, not much can be done about the fake PGP keys."
Re:The chain of trust is broken. (Score:4, Informative)
Re:x.509 WTF? (Score:4, Informative)
Never mind that we don't need to switch to X.509, we can add X.509 certs to OpenPGP.
When you think about it, in the web-of-trust model centralized certificate authorities are just entities that a lot of people happen to trust; there's absolutely nothing stopping us from taking X.509 certs and adding them to OpenPGP keys as just another type of signature and the X.509 certificate providers have no (technical) means of stopping people from doing that.
I've argued before to the Bitcoin community that what we really want is a "best of both worlds" solution where we support centralized certificate authorities via X.509 and OpenPGP for applications with low security needs while maintaining the ability to use the WoT for those applications with higher needs. It's totally OK if average user just uses software that automatically checks the X.509 cert or OpenPGP signature issued by a certificate authority when they download some wallet software or make a payment to someone. Meanwhile advanced users, and particularly developers, can check all the signatures, WoT, certificate authority, whatever, to be sure they have the right software when they're downloading "clean" copies for their Bitcoin exchange, or making high-value payments.
What really amazes me is how people seem to think this is a binary decision, centralized PKI or WoT. It's not at all! Heck lots of organizations already apply the central certificate authority model with OpenPGP - just looks at all the Linux distributions that have master OpenPGP keys to sign packages. That's a certificate authority, but with OpenPGP technology.
Mike Hearn has been lately going on a bit of a war-path trying to push Bitcoin into a model of blind reliance on singular centralized PKI authorities and frankly it's just nuts. He's even gone as far as to strongly advocate that we don't even support multiple X.509 certs for applications, which would at least require an attacker to compromise more than one certificate authority. This is particularly crazy when at the same time he has advocated that websites, e.g. bitcointalk, reddit, slashdot, etc. sign cryptographic certificates linking usernames to identities. The idea here is if I want to pay "IamTheRealMike" my wallet software could have, say, slashdot's certificate pre-loaded and trusted, and then I'd tell it to give the funds to that username. But why would I do that? I want to pay Mike Hearn. I happen to know he's "IamTheRealMike" on slashdot.org, and "Mike Hearn" on bitcointalk, so obviously if it's a non-trivial sum of money I'd want to be able to check that both sites have stated that they're the same person, and maybe I'll check WoT too, and, say, his countries passport office. It just makes so much sense to give people options like that, but we're rather mysteriously seeing resistance. If anything, I think it's kinda insulting to the professionals in this space, both developers and finance people, to tell them "We're all too stupid to learn about anything more complex than trusting the magic green checkbox". If I was running a big Bitcoin-related business I sure as hell would want more assurance than that; when I'm writing software used by others I sure as hell want more assurance than that.
Anyway, in the OpenPGP world I'm really excited to see KeyBase [keybase.io] pop up. It's not perfect - the functionality probably should have been just an add-on to OpenPGP rather than a website - but it's a great step in the right direction of giving flexibility and user-friendlyness to the WoT. It also works great as a local application, so if you choose to you aren't relying on their website/service for the guarantees it provides.