default secret key for decryption

[Maxim Britov]

> > File encrypted for four people, man operating now in the system is
> > third (he appears third in the list of persons for whom file was
> > encrypted). How can I specify that I'm going to decrypt file using
> > third key?

> If you do not respond to the first two prompts, GnuPG will use the
> third key to decrypt.  Just enter a blank passphrase.

Can I get all keyids for encrypted message?
Why I cannot use --default-key for decrypt? 

-- 
MaxBritov

GnuPG KeyID 0x6F3DB1FB Keyserver hkp://keyserver.kjsl.com
Fingerprint: 4059 B5C5 8985 5A47 8F5A 8623 4580 A6D6 6F3D B1FB