Debian preferred maintainer pgp key parameters?

[Bill Mitchell <mitchell@mdd.comm.mot.com>]

I'm intending to start changing change the maintainer address
on my packages to "Bill Mitchell <mitchell@master.debian.org>".
Since this will involve generating a new pgp key, I'd like to
use whatever key parameters are preferred for Debian maintainers.

What's preferred -- 512, 768, or 1024 bits?