[dm-crypt] MK Digest Size
jorge.fabregas at gmail.com
Sun Jul 10 18:59:51 CEST 2011
On 07/10/2011 12:29 PM, Jorge Fábregas wrote:
> I still get to see 20 HEX characters (160 bits) for the MK digest?
I'm sorry. I meant 20 pairs of HEX characters (40 chars) as they appear
nicely formatted in the luksDump output.
> Shouldn't I see 32 HEX chars (256 bits)?
Same here (64 hex characters ).
> Or is that sha256 is used in the PBKDF2 process but the function is
> instructed to deliver just 160 bits?
Ok, I'm going to try to answer myself as I just read again the latest
specification. It appears this is the case (just 160 bits even if you
use sha256) because there are just 20 bytes available for "mk-digest" in
I'm just curious: is having just 20 bytes for the digest a limitation
here? Are there any plans to expand this field in the future?
> One final thing just to make sure: is the algorithm that appears under
> "Hash spec" in the header..is this the same hash-algorithm used (along
> with PBKDF2) for the user-keys? as well as the one used with PBKDF2 for
> the MK digest?
Sorry for the noise!
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