On 09/24/2012 11:55 AM, Dmitry Kasatkin wrote:

Both dm-verity and dm-crypt provide block level integrity protection.

This is not correct. dm-crypt is transparent block encryption target,
where always size of plaintext == size of ciphertext.

So it can provide confidentiality but it CANNOT provide integrity protection.

We need extra space to store auth tag which dmcrypt cannot provide currently.

dm-integrity provides a lighter weight read-write block level integrity
protection for file systems not requiring full disk encryption, but
which do require writability.

Obvious question: can be dm-verity extended to provide read-write integrity?

I would prefer to use standard mode like GCM to provide both encryption and
integrity protection than inventing something new.

Milan