Hello,

I'm trying to implement support for opening DiskCryptor partitions. DiskCryptor 
is licensed under GPLv3, which is incompatible with libcryptsetup's LGPL2+. I'd 
therefore prefer not to read DiskCryptor source code. I'm asking for someone to 
do this and provide some information - mostly about header encryption ATM.

I tried to reverse-engineer the format from public info:

  * https://diskcryptor.org/volume/
  * https://security.stackexchange.com/a/83792

and by trial and error, but failed.

I've tried the following (with many variations) on a FAT partition encrypted 
with AES:

 1. Password is encoded as an ASCII string.
 2. This ASCII string is hashed with PBKDF2 with the following parameters:
      * hash: sha512
      * salt - 64 bytes from start of the volume header,
      * output size: 64 or perhaps 192 bytes,
      * 1000 iterations.
 3. Encryption key consists of the first or perhaps last 64 bytes (512 bits) of
    the output of PBKDF2.
 4. Bytes 64 - 2048 of the header are encrypted with AES cipher in XTS mode:
      * decryption starts from byte 64,
      * IV is 16 bytes long.

Code could be found at https://github.com/DavidXanatos/DiskCryptor/ . Thank you 
in advance.

Greetings,

Mateusz Jończyk