Microsoft’s BitLocker is, for all we know, a proper disk encryption software. It encrypts data at rest against attacks originating outside the running system. If you use BitLocker and your computer is stolen while turned off, there is essentially no way of reading data from the disk without having the proper key(s)—your BitLocker PIN, a key file on a USB stick, or both. If an attacker gets access to the machine while it is running, there may be ways of compromising it through Windows or in other ways, but such attacks are clearly outside the scope of disk encryption.
We know, however, another class of attacks against disk encryption: evil maid attacks. This term describes a general strategy rather than a particular implementation. If you leave your computer unattended, let’s say in a hotel room, an attacker, let’s say an evil maid, might manipulate it such that your data will be compromised as soon as you return and provide it with your encryption keys. There are various ways of doing so, for instance installing a hardware keylogger if your keys are based on passwords, or altering the unencrypted boot code to install a Trojan horse that will leak your keys later. The Evil Jan Attack weiterlesen