dropbear/init: Allow extra arguments for key generation
This patch adds DROPBEAR_RSAKEY_ARGS and DROPBEAR_DSSKEY_ARGS optional
parameters to /etc/default/dropbear. The contents are simply passed to
the 'dropbearkey' program when generating a host key.
The default keysize for RSA is currently 2048 bits. It takes a CortexA9
running at 700MHz between 4 and 10 seconds to calculate a keypair. The
board boots Linux in about a second, but you have to wait for several
seconds because of the keypair generation. This patch allows one to put
the line DROPBEAR_RSAKEY_ARGS="-s 1024" into /etc/default/dropbear, and
have a host key generated in about 0.2 seconds on the same CPU. This is
particulary useful for read-only rootfs systems which generate a key on
each boot.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> Signed-off-by: Ross Burton <ross.burton@intel.com>
