Hi,

--- Michael Gile <mgilemac.com> wrote:
> The security problem with smart cards is not key recovery. It is the
> fact
> that the smart card must rely on a standard PC (or other insecure
> host) for
> input and output.
>

I consider this argument inaccurate. The smartcard does not necesary
needs a PC to run. You attach the smartcard to a PC reader to allow
some application on your PC to get benefit of the smartcard. But your
smartcard system (PC application + smartcard) will never be more secure
than your host PC alone. The smartcard system cannot replace good
handling of the user access to the computer resources by the OS.

> For example, say we have a smart card with a signing application that
> will
> sign arbitrary data from the host PC (an oracle). The attacker no
> longer
> needs access to the key, only an application that can send data to
> the card.
> Even when adding authorization to the key usage (for example a PIN),
> an
> attacker needs only access to the insecure host machine and can then
> recover
> the PIN itself or send bogus data to be signed.
>

IMHO this is a application design problem, and not a problem on the
smartcard industry itself. You *must not* have an application signing
arbitrary data from anybody that request that. Would you run a daemon
that gets data from anybody and encrypts/signs this data with your
private key "safely" stored on your hardisk? The same applies if the
key was generated onboard on your smartcard.

> The solution to the smart card attacks above is to add a secure
> communication channel to some special purpose server through which
> only
> encrypted data is ever transmitted outside the card, or provide a
> more
> robust mechanism to the user that can be used for secure input and
> allows
> more storage and computing power on the card itself.
>

The smartcard must be managed by the OS like other normal device, lets
say the printer or the harddisk. Once a user has logged into the
system, he/she may or may not have access to the smartcard, depending
on system priviledges of this user. Under UNIX this is perfectly
handled by regular file permissions to read/write from the smartcard.

Carlos.

> Regards,
>
> Michael Gile
> Wave Systems Corp.
> mgilewavesys.com
> mgilemac.com

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