[systemd-devel] Partition with random key in crypttab

[Some Body]

Hi, I'm not experienced at all with systemd, and not much more in system 
administration, and I don't know if I should post this here, but it is 
the only list I found that seems to provide general support for systemd.

I want to encrypt my /tmp directory by putting it in an encrypted 
partition (sda9). I put the following line in /etc/crypttab :

> crypttmp /dev/sda9 /dev/urandom tmp=ext4,cipher=aes,size=256,hash=sha256

...and the following in /etc/fstab :

> /dev/mapper/crypttmp /tmp ext4 defaults 0 2

but when I boot, systemd hangs for 1:30, saying that "a startup job is 
running for dev-mapper-crypttmp". Then it fails, and the encrypted tmp 
is not mounted.

I'm on Debian Jessie, if it can help.

What is the recommended way to mount an encrypted partition with a 
random key ?

Thanks.