GPG and PGP

[David Shaw]

On Mar 16, 2011, at 9:41 AM, vedaal at nym.hush.com wrote:

> David Shaw dshaw at jabberwocky.com wrote on
> Wed Mar 16 00:42:48 CET 2011 :
> 
> 
>> GnuPG does the MDC by default whenever all the keys can handle it 
> 
> What kind of key can't handle it in gnupg?

None.  It's not a key type, but a feature/detail of the implementation, like supporting a particular cipher.  The user IDs have a flag on them to indicate whether an MDC can be used.

Run gpg --edit-key on your key and enter "showpref".  Look at the "Features" line(s).  They should say (among other stuff) "MDC".  That's the flag.

Forcing the use of the MDC is similar to forcing the use of a cipher: it might work (probably will, these days), but if someone is using an implementation that doesn't understand the MDC, they won't be able to decrypt your message, any more than they would be if you forced the use of a cipher their implementation doesn't understand.

David