If you create a new GPG key, you'll by default get a signing-only master key pair and an encryption-only sub-key pair.
pub 2048R/XXXXXXXX created: 2013-02-09 expires: 2014-02-09 usage: SC sec 2048R/XXXXXXXX 2013-02-09 [expires: 2014-02-09] sub 2048R/ZZZZZZZZ created: 2013-02-09 expires: 2014-02-09 usage: E ssb 2048R/ZZZZZZZZ 2013-02-09 [expires: 2014-02-09]
(Output combined from
gpg --list-keys and
It's also recommended to not use your master key for regular signing (of mails/data), but to create another signing-only sub-key and remove/backup your master key to a safe and offline location only to be used for key-signing.
This makes sense as most encryption endpoints are laptops/phones or other always-online, mobile devices which put your private keys at risk of theft or loss. With a securely stored master key, you can always revoke such lost sub-keys and never loose your key signatures.
So while the master-key <-> sub-key separation is clear to me, I don't understand why there is this emphasis on separating signing and encryption keys (even if they are both sub-keys). Can somebody explain why this is necessary or at least what the advantage is from a security or practical perspective?
Technically it's entirely feasible and supported by GnuPG to create a signing AND encrypting sub-key.
pub 2048R/YYYYYYYY created: 2013-08-13 expires: 2014-08-13 usage: SCEA sub 2048R/VVVVVVVV created: 2013-08-13 expires: 2014-08-13 usage: SEA