Re: A patch to loop.c for better cryption support

[David Wagner]

Ingo Rohloff  wrote:
>> There is a paper about why it is a bad idea to use
>> sequence numbers for CBC IV's. I just have to find the reference to it.
> 
>Does this mean sequence as in 0,1,2,3,4 ... or does this mean
>any pre-calculate-able sequence ? In the former case we might just use
>a simple one way hash-function over the requested sector number.

It just means that 0,1,2,3,... is bad.  Using SHA1(sector #) should be ok.

But do think carefully about what happens when you modify a sector!!
In particular, will you be re-using the old IV when you write the new
data?  That could be problematic.
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