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From: Brashen on 15 Apr 2010 11:23
Hi,

I was wondering: all experts seem to agree that, although not endorsed
as a standard any more, DES will stay around for several years before
disappearing (for legacy reasons, backward compatibility, slow
replacement procedures...).

So, are you aware of applications or products that would:
- still be in use;
- and use DES (not triple-DES, that would be a different debate)?

Thanks
From: Paul Rubin on 15 Apr 2010 16:38
Brashen <nospam(a)wanted.net> writes:
> So, are you aware of applications or products that would:
> - still be in use;
> - and use DES (not triple-DES, that would be a different debate)?

In the mid-2000's there was a big effort under way to upgrade the credit
card payment networks to triple DES. I don't know about now, but I
suspect that at least some of the older stuff is still in use in some
places. We're talking about those payment terminals that you swipe your
card through, that are in just about every corner store in every country
that uses credit cards a lot. To go completely to triple-DES, tens of
millions of those things would have had to be taken out of service or
replaced, and it wouldn't surprise me if some of them are still being
supported.
From: Thomas Pornin on 15 Apr 2010 17:28
According to Paul Rubin <no.email(a)nospam.invalid>:
> We're talking about those payment terminals that you swipe your card
> through, that are in just about every corner store in every country
> that uses credit cards a lot.

Except France. In France, all credit cards are smartcards; they are
not swiped but inserted, and the magnetic band is not used.

(That's quite normal. Smartcards are a French invention from the
late 80's. Rather than sending royalties to the damn froggies, all
other countries patiently waited for the patent to expire. Notice
how North American banks are _now_ advertising smartcards as the
best technological advance since sliced bread ? A patent expires
after twenty years...)


> To go completely to triple-DES, tens of millions of those things would
> have had to be taken out of service or replaced, and it wouldn't
> surprise me if some of them are still being supported.

A rather fine property of 3DES is that it is backward compatible with
simple DES. That's because the "middle" DES instance is used in reverse
(3DES is encrypt-decrypt-encrypt rather than encrypt-encrypt-encrypt).
Thus, for every DES key, there are some equivalent 3DES keys which yield
the same encryption result. I would not be surprised if most DES-aware
hardware was actually 3DES-aware, and possibly using 3DES transparently
when possible.


--Thomas Pornin
From: unruh on 15 Apr 2010 21:21
On 2010-04-15, Thomas Pornin <pornin(a)bolet.org> wrote:
> According to Paul Rubin <no.email(a)nospam.invalid>:
>> We're talking about those payment terminals that you swipe your card
>> through, that are in just about every corner store in every country
>> that uses credit cards a lot.
>
> Except France. In France, all credit cards are smartcards; they are
> not swiped but inserted, and the magnetic band is not used.
>
> (That's quite normal. Smartcards are a French invention from the
> late 80's. Rather than sending royalties to the damn froggies, all
> other countries patiently waited for the patent to expire. Notice
> how North American banks are _now_ advertising smartcards as the
> best technological advance since sliced bread ? A patent expires
> after twenty years...)

I think the primary purpose of the smartcards is that the company can
claim that any fraud is your fault and they do not have to reimburse
you. After all you must have revealed your pin if they use it. That
almost all the terminals are so terribly located that it is trivial to
shoulder surf is not their fault, so it is yours.


>
>
>> To go completely to triple-DES, tens of millions of those things would
>> have had to be taken out of service or replaced, and it wouldn't
>> surprise me if some of them are still being supported.

In canada by next year, ALL terminals are supposed to be smartcard
terminals. Ie, no old ones are supposed to remain.


>
> A rather fine property of 3DES is that it is backward compatible with
> simple DES. That's because the "middle" DES instance is used in reverse
> (3DES is encrypt-decrypt-encrypt rather than encrypt-encrypt-encrypt).
> Thus, for every DES key, there are some equivalent 3DES keys which yield
> the same encryption result. I would not be surprised if most DES-aware
> hardware was actually 3DES-aware, and possibly using 3DES transparently
> when possible.
>
>
> --Thomas Pornin
From: Paul Rubin on 15 Apr 2010 22:12
Thomas Pornin <pornin(a)bolet.org> writes:
> I would not be surprised if most DES-aware hardware was actually
> 3DES-aware, and possibly using 3DES transparently when possible.

I'm sure a lot of it is, but at the time I was working with it, a lot
wasn't. Remember that payment terminals are high-volume electronics
like mobile phones or cd players, so they're subject to intense
cost-reduction efforts. If they make 1 million units of some terminal,
then implementing a 10-cent-per-unit cost savings puts $100,000 into
somebody's pocket. They don't put features into the hardware that they
don't absolutely have to.
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