Auto de-crypt all LUKS partitions in Debian

I use Debian Wheezy and have all partitions encrypted using LUKS, except /boot. I want to decrypt the partitions automatically without having to type the password in each of the 7 encrypted partitions (same for all 7). How I can do this? With cryptsetup? How do I make the hook script from initramfs?

/boot: No crypt
/: crypt
/home: crypt

I need to decrypt / and /home in initramfs in Debian.