Plausible Deniability In case an adversary forces you to reveal your password, TrueCrypt provides and supports two
kinds of plausible deniability:
1. Hidden volumes (for more information, see the section
Hidden Volume below) and hidden
operating systems (see the section
Hidden Operating System ).
2. Until decrypted, a TrueCrypt partition/device appears to consist of nothing more than
random data (it does not contain any kind of "signature"). Therefore, it should be impossible
to
prove that a partition or a device is a TrueCrypt volume or that it has been encrypted
(provided that the security requirements and precautions listed in the chapter
Security Requirements and Precautions are followed). A possible plausible explanation for the
existence of a partition/device containing solely random data is that you have wiped
(securely erased) the content of the partition/device using one of the tools that erase data
by overwriting it with random data (in fact, TrueCrypt can be used to securely erase a
partition/device too, by creating an empty encrypted partition/device-hosted volume within
it). However, you need to prevent data leaks (see section
Data Leaks ) and also note that,
for system encryption, the first drive track contains the (unencrypted) TrueCrypt Boot
Loader, which can be easily identified as such (for more information, see the chapter
System Encryption ). When using system encryption, plausible deniability can be achieved
by creating a hidden operating system (see the section
Hidden Operating System ).
Although file-hosted TrueCrypt volumes (containers) do not contain any kind of "signature"
either (until decrypted, they appear to consist solely of random data), they cannot provide
this kind of plausible deniability, because there is practically no plausible explanation for the
existence of a file containing solely random data. However, plausible deniability can still be
achieved with a file-hosted TrueCrypt volume (container) by creating a hidden volume
within it (see above).
Notes •
When formatting a hard disk partition as a TrueCrypt volume (or encrypting a partition in
place), the partition table (including the partition type) is
never modified (no TrueCrypt
“signature” or “ID” is written to the partition table).
•
There are methods to find files or devices containing random data (such as TrueCrypt
volumes). Note, however, that this should
not affect plausible deniability in any way. The
adversary still should not be able to
prove that the partition/device is a TrueCrypt volume or
that the file, partition, or device, contains a hidden TrueCrypt volume (provided that you
follow the security requirements and precautions listed in the chapter
Security Requirements and Precautions and in the subsection
Security Requirements and Precautions Pertaining to Hidden Volumes ).