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 her key, he 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."