On Thu, 18 Feb 2016, John R Levine wrote:
One other issue that hasn't come up is the security model, in particular what it means for a domain to publish PGP keys that it claims are associated with mail addresses in that domain.
The security model is not changed. As stated, it is not a replacement for the web of trust. It is another more secure location to find the key. It can be used where otherwise a message would go out unencrypted.
In sections 1 and 7, it claims that finding a key through DNS lookup is not a substitute for web-of-trust verification, which is fine. But section 5.2 says that if a domain publishes a key for an address that's inconsistent with an existing key, verification of the key is "treated as a failure." It's unclear what the effect is supposed to be, but considering the discussion of the lost key problem, it appears that the intent is that the sender would stop using the old key.
Local policy.
Maybe a domain is an investment advisor ensuring that it can log its employees' mail, or maybe it's webmail that wants to snoop on its users to add intrusive advertising. Unless a sender has external knowlege of the relationship between a domain and its mail users, a can of worms that I wouldn't want to open, this is in effect a downgrade attack.
That situation is unchanged from today. With the exception that plaintext email could have been encrypted email. It's not a downgrade.
PGP has always associated keys with users and put users in control of their keys; the inability to delete lost keys from keyservers is an effect of that.
You are just cherry picking one argument. A much more severe argument is people uploading forged keys. Ask Mr. Snowden and Mr. Assange.
This draft moves a lot of that control to domain operators. That may or may not be a good idea but it's a large change to the security model.
It does not move control around. The draft clearly states it is an addition to the existing web-of-trust, not a replacement. It facilitates more automated encryption where before messages would go out in plaintext. Paul