Overall structure

The overall TeaSafe image basically looks like this:

IV is a 32-byte (i.e. 256 bit) initialisation vector used by the encryption algorithm and is serialised unencrypted. Header is a further 8 byte sequence. The first byte stores the number of rounds used by the encryption process if the algorithm requires it (a maximum of 255). The second byte indicates the encryption algorithm (aes == 1; twofish == 2; serpent == 3; rc6 == 4; mars == 5; cast256 == 6). As with the IV, these bytes are serialised unencrypted. The remaining 6 bytes are currently unused and are just padded with the same value as the second byte.

Typically also, the root folder entry starts at block 0.