I understand all those things in general, but I don't know the specific mechanism by which my local PGP install recognizes who else trusts this PGP key. I grant you that if the key is protected from MITM then all is well. I just still don't know this part:
What mechanism do I use, I who have no prior encounter with that key and no existing PGP setup or connection to any web, to validate that key?
I'm sure this is just a lack of familiarity with PGPs web of trust implementation, but lacking this info, I too just opted to trust the plain HTTP download (until I switched to Cygwin/OpenSSH to make it a moot point anyway).
xargs speeds the process by requesting multiple keys at a time. I think keeping that below 20 keys helps keep the keyservers happy. Sort + uniq eliminates duplicate requests of the same key.
You cannot run parallel processes as your local gpg instance cannot do concurrent updates to the keyring.
The WoT is both PGP's strength and weakness. Lacking anything else, key security staff for various Linux distributions and key EFF members isn't a bad starting point for this. Assigning those "marginal" trust means that you'd have to have three of those signing a given key to trust it.
Never mind, I see a higher ranked comment got an answer to this. I see the concept of keys signing keys and gpg --list-sigs. (Still no idea who might be at the end of that chain that I could actually verify though.)
I understand all those things in general, but I don't know the specific mechanism by which my local PGP install recognizes who else trusts this PGP key. I grant you that if the key is protected from MITM then all is well. I just still don't know this part:
What mechanism do I use, I who have no prior encounter with that key and no existing PGP setup or connection to any web, to validate that key?
I'm sure this is just a lack of familiarity with PGPs web of trust implementation, but lacking this info, I too just opted to trust the plain HTTP download (until I switched to Cygwin/OpenSSH to make it a moot point anyway).