TrueCrypt: pro and contra

Question

What are possible drawbacks of using TrueCrypt? Do I risk losing my data in case of some disk error?

Answer 1

Two cases: full system encryption and disk images.

With full system encryption Truecrypt requires burning restore CD. That can be used to restore broken disk header, due to disk failure or data corruption. With that it is possible to decrypt disk, even if something is corrupted. Restoring disk contents using some commercial service might pricey/impossible when there is disk encryption added.

With disk images by default there is no backup of disk header. Therefore, corruption in the beginning of disk destroys all contents (do not destroy, but you have no way to access those).

Disk header is important, as your passphrase is only decrypting encryption key from header. That encryption key is then used for disk encryption/decrypting.

Quote from Truecrypt FAQ:

What will happen when a part of a TrueCrypt volume becomes corrupted?

In encrypted data, one corrupted bit usually corrupts the whole ciphertext block in which it occurred. The ciphertext block size used by TrueCrypt is 16 bytes (i.e., 128 bits). The mode of operation used by TrueCrypt ensures that if data corruption occurs within a block, the remaining blocks are not affected.

16 bytes is rather tiny part of typical disk, only 0.00000149% of one gigabyte.