Re: [tlug] Managing PGP keys on multiple machines

[David Smith <dds@example.com>]

Hi Mike,

The solution you're looking for is using PGP subkeys. There is a howto
at http://fortytwo.ch/gpg/subkeys. Read that page and then come back to
this email for more tips.

<waits while Mike reads ...>

Here are some tips:
 + Keeping the actual private key offline and only using subkeys on your
   desktop and laptop is more secure. Consider a USB key for the storage
   of your actual private key (you will still need it to decrypt
   encrypted messages).
 + Consider using a smartcard to store your subkeys. There is a howto
   for using the Fellowship / OpenPGP card for this at
   http://www.gnupg.org/howtos/card-howto/en/smartcard-howto-single.html
 + What's that? You don't want to buy any hardware and smartcards are so
   90s? Using the GnuPG PKCS#11 Smartcard Daemon at
   http://gnupg-pkcs11.sf.net/ and openCryptoki from
   http://opencryptoki.sf.net/, you can store your subkey in either a
   smartcard emulation layer protected by the opencryptoki daemon
   (equivalent to something like OSX's keychain) or even store the
   subkey in the TPM chip of your laptop, if you have one but most laptops
   do, for the ultimate in security.

I have a thinkpad and so I use the TPM chip option. There's not much
documentation for all of this so if you are interested, first start with
the subkeys howto and then ask away.

Cheers,
dds

Mike Mazur <mmazur@example.com> writes:

> Hello,
>
> How would you manage your PGP key on multiple machines?
>
> Say I have a desktop machine and a laptop. On my desktop I create a
> public/private key pair with a strong passphrase. I use this key pair
> to sign emails.
>
> I would also like to send signed emails from my laptop. I could simply
> transfer the private key from my desktop to my laptop. But what if I
> lose my laptop? Since an attacker will have physical access to the disk,
> will the passphrase be sufficient to maintain my secret key?
>
> The other alternative is to create a new key pair for the laptop (but
> the same identity). This becomes an inconvenience for those I
> communicate with as they now must keep track of my multiple public
> keys. If the laptop goes missing, only that one key can be revoked.
>
> Thanks,
> Mike
<#secure method=pgpmime mode=sign>