johan.wallen+lists@tkk.fi (Johan Wall=E9n) writes:

>> IV Methods
>>   Currently, the only IV Method supported is encblkno (Encrypted Block
>>   Number).  This method encrypts the block number of the physical disk
>>   block with the cipher and key provided and uses that as the IV for CBC
>>   mode.  This method should ensure that each block has a different IV
>>   and that the IV is reasonably unpredictable.
>
> The basic idea does sound good.  But what is a block number in this
> context?  Logical/physical block number on the disk/filesystem?  What
> IV is used when a block is modified?

Apparently, I cannot read, so let me rephrase my question.  When
encrypting a block on a disk, the block number and the key is used to
derive the IV.  When the block is modified and encrypted again, is the
same block number and the same key used to derive the IV?  If not, how
are the IVs actually derived?=20=20

-- Johan