Version Information

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
). 

---

38