Most of the public keys I am getting from friends have a
sub key in addition to the
pub key. For educational purposes I retrieved some public keys and came across this Linus Torvalds' key that does not have a sub-key.
pub 1024D/956EB7BF449FA3AB 1999-10-05 [expired: 2001-10-04] uid [ expired] Linus Torvalds <firstname.lastname@example.org>
Apparently this key is distributed without a
sub key. My own public key looks like this (anonymized for posting purposes).
pub 4096R/96Q1DUTLHW3NHA97 2014-10-27 [expires: 2015-03-11] uid [ unknown] First Name Last Name <email@example.com> sub 4096R/96Q1DUTLHW3NHA96 2014-10-27 [expires: 2015-03-11]
Why would people distribute their public key with a sub-key and what are the advantages of doing that or not doing that?