pgut001@cs.auckland.ac.nz[SMTP:pgut001@cs.auckland.ac.nz]
"Trei, Peter" <ptrei@rsasecurity.com> writes:
It's a move in the right direction, but I wish they had followed through
and
done the right things:
* [AES | 3DES]/CBC
I get the feeling they use ECB for speed (heavy pipelining) rather than
cluelessness.
Possibly - they're using an ASIC, so I'd have thought that speed would not
be the issue. I have not run the numbers.
with a good distribution of IVs
Where would you store them? The feature of this is that it's fully
transparent, so you can't store IVs anywhere.
I'm not really up on crypto file systems, but I beleive at least some
use the sector address as the IV. IVs don't need to be random,
secret, or unpredictable - they just need to be unrepeated. (I'm
assuming sector-at-a-time encryption).
* User-generated keys (before initial disk setup, of course).
That one's the only thing I can't find a good technical reason for...
perhaps
it's just commercial, since they see the dongles as a revenue source and
will
sell you software to set up n dongles yourself, where price is
proportional to
n.
Having the user generate the key and load it on the dongle
means that he has good assurance that the manufacturer doesn't
have the key. Any kind of backup will open a possible route of
attack. If the user can specify the raw key value (it's short - this
is symmetric crypto), they can choose their own backup - up to
and including writing it on paper and carefuly hiding it.
* Some kind of PIN or password protection on the dongle.
How would you do this without a custom BIOS (remember that their general
product is for dropping into any PC)?
We're talking about two different products. The ABIT is a MB,
presumably with it's own custom BIOS, so that's not an issue
there.
40 bit DES is not secure against your kid sister (if she's a cypherpunk
:-),
much less industrial espionage.
I'm more worried about key backup - it's bad enough having
cheapest-possible-
components IDE drives without complicating it further with a second point
of
failure. In the meantime a better option is still the triumvirate of:
- Sensitive data saved only to RAM disk.
- 3DES-encrypted volume mounted as a filesystem, which I can back up in
encrypted form if necessary, and with all crypto done in software with
per-
sector random IVs, user-generated keys, and all the other stuff you
asked
for.
- Encrypted swap.
(Oh yeah, and a UPS so you're not tempted to temporarily save stuff to
disk
elsewhere in case the RAM drive goes away suddenly).
"40-bit DES (US Data Encryption Standard) is adequate for general users"
Yeah. Right.
If you're worried about Joe Burglar grabbing your laptop (for the value of
the
laptop) and your business data being leaked as collateral damage, or
someone
stumbling across your warez or pr0n, then it's probably adequate. Since
this
is what general users would be worried about, I'd agree with the
statement.
Anyone worried about more than that (probably about 0.01% of the market)
isn't
a general user any more.
Peter.(G)
Peter (T)