"No-Keyserver" (and other) flags on keys

[David Shaw]

On Jun 27, 2010, at 7:50 PM, Dan Mahoney, System Admin wrote:

>>>> It's effectively a no-op though, as no server supports it.
>>> 
>>> I'm looking into making mods to at least one server type (we run one locally at work), and commit them upstream.  If I'm going to wade into that muck, I might as well have multiple things to try to make work.
>>> 
>>> The change in the key file format is the "hard" part :)
>> 
>> Having keyservers support no-modify requires that they first support crypto at all.  That's a really big step.
> 
> The ones I've seen have enough awareness of what's in a key to pull a key apart and determine who's signed it, when, and when it's expired.  Is there more than that to read these bits?  Again:step zero may be to determine what the internal format is.

Vastly more.  Keyservers are basically databases with a front-end that understands the OpenPGP key format.  They don't actually do any crypto math - just storing the key packets in the database and allowing people to search for them.

> However, you raise another question: How does a keyserver know who is uploading the key?

At the moment, it doesn't.  That would need to be addressed if you want keyservers to be able to reject a no-ks-modify key.  One way to do it is to only accept key updates that are signed by the key itself.  But, of course, to do that, the keyserver needs to be able to verify a signature...

David