the idea of using encryption for your hard drive is to protect your private data
but, it seems that this kind of protection is not as safe as it used to be any more
the thing is, now you can make a copy of RAM (computer memory) as soon as it is turned of or at any time if the computer is in sleep mode and you’ll find the encryption key there
many disk encryption programs are at risk, including Windows BitLocker, linux dm-crypt and Mac software
take a look at this video