GPF Crypto Stick vs OpenPGP Card

Marcio B. Jr. marcio.barbado at
Fri Dec 3 14:55:34 CET 2010

let me utilize this thread to clarify something.

I've never used those external devices, and my private keys have
always been one place only located, a computer.

That situation is a sort of "trade-off" for it keeps the referred keys
more protected/restricted whereas it gives me little chance of using
them in other hosts, easily.

So, I guess one of the ideas behind making use of those devices would
be the facility of taking all of my keyrings ("secring.gpg" for
example) with me everywhere, is it correct? If so, by doing that,
weren't we losing the whole point?


On Fri, Dec 3, 2010 at 10:21 AM, Hauke Laging
<mailinglisten at> wrote:
> Am Freitag 03 Dezember 2010 09:47:27 schrieb Nils Faerber:
>> The non-obvious content of the transaction, what you say as "you do not
>> see what you sign even on the PIN-pad" is an issue that has been
>> discussed a lot of times already - yes, it is definitely an issue but
>> very hard to solve. IMHO this would require a card terminal that
>> understands the data to be signed and present the user with a meaningful
>> summary.
>> But it strictly assumes again that this terminal cannot be compromised
>> too. And being more intelligent (in order to display complex data) means
>> to be a more complex device containing more complex device software
>> which again opens new possible security holes.
> A first improvement would be to show the hash to be signed. Of course, you
> cannot trust the hash calculation on a potentially compromised PC but this
> would be a start for further protection (e.g. by sending the file to someone
> else and comparing the hashes).
> If I understand the process correctly then not the file hash is signed but the
> hash for a combination of the file hash and some metadata (timestamp, signer
> ID). For a security progress the card reader would have to see both hash
> components which would require a protocol change. IMHO it makes sense to plan
> this for the future. Ask the card reader whether it has a display and can do
> the hash calculation itself. If so then send the data in a new format.
> Hauke
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Marcio Barbado, Jr.

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