GnuPG key storage on Palm?

Werner Koch wk at
Wed Dec 26 12:14:05 CET 2001

On Mon, 24 Dec 2001 11:46:20 -0600, Andy Steingruebl said:

> I'm trying to determine the feasibility of storing keyrings on a palm pilot,
> and doing any private computation there.  I've seen a few discussions of

IIRC, Brian Warner did some experiments with that.  There is a
prototype implementation to do secret key operations on an iButton
( which is much less powerful than any PDA.

> this topic come up, and mostly they said "a PDA is too slow for the
> necessary operations."  I haven't however seen much formal treatment of the

That is not true: Remember back in 1993 when PGP 2 got more and more
popular, the average desktop box was slower than a modern PDA.  Of
course you should only do the public key encryption and run the bulk
encryption on the regular machine.  There is not much security risk
with that because you usually keep and edit your plaintext on that
machine anyway.

External tokens are very good to protect the secret key against remote
attacks and even against a trojaned desktop box.

> I believe the GpgAgent work might solve part of the problem, if PKCS#11 and
> PKCS#15 support evolves for GnuPG, then I'd just need a PDA that supports

I more and more come to the conclusion, that pkcs 11 and 15 is not
what we want for gpg-agent; a main goal of those standards is to allow
independent proprietary applications work together - there is not much
need for such a goal in the Free Software world.  What I have in mind
and going to implement in January is a Smartcard daemon with a simple
interface to be used by gpg-agent.  By putting such a daemon with the
same interface (using a serial line or USB instead of an Unix Domain
Socket) onto a PDA, you get what you want.  gpg-agent will then
delegate all requests for unknown keys to the PDA.  Another way to
achieve the same result would be by movin the gpg-agent directly to
the PDA, but this has the drawback that it will not be possible to
keep (not so important) secret keys on the desktop box.

The protocol will also allow to send the entire plaintext to the PDA,
so that it can be viewed and signed on that TCB.

> Pointers to documentation and or project pages appreciated. will eventually have some documentation
on this.


Werner Koch        Omnis enim res, quae dando non deficit, dum habetur
g10 Code GmbH      et non datur, nondum habetur, quomodo habenda est.
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