Is LUKS key wiped out from RAM on shutdown, hibernation and suspend?

Question

The question is basically whether Ubuntu is protected from cold boot attacks.

Answer 1

This question has several answers on SuperUser. But basically the answers say that if you don't use old RAM modules (DDR2 and back) you should not worry about this. This has nothing to do with the Operative System, through you can apply additional protection at OS level wiping the memory at shutdown.

In case you have old modules, you can activate "Activate Autostart at Power loss" (this changes between BIOS) and doing "RAM check at boot time" (this will slowdown your boot).

Rewording mnmnc's answer, if you want to protect your Ubuntu installation:

Do you want a secure way of shutting down the PC? Here it is:

1. Keep secure data in True Crypt cascade algorithm encrypeted file
2. Use Serpent

3. Create a script to handle shutdown:

   truecrypt /wipecache
   shutdown -h now
   

/wipecache ensures that no vulnerable data remains in RAM after shutdown. If someone will perform Cold Boot Attack they will have access to your System at best. They will not have data stored in a separately encrypted file.