Using Gnuk Token with another computer¶
This document describes how you can use Gnuk Token on another PC (which is not the one you generate your keys).
Note that the Token only brings your secret keys,
while .gnupg directory contains keyrings and trustdb, too.
Fetch the public key and connect it to the Token¶
In order to use the Token, we need to put the public key and the secret
key references (to the token) under .gnupg directory.
To do that, invoke GnuPG with --card-edit option.
Reader ...........: 234B:0000:FSIJ-1.2.0-87193059:0
Application ID ...: D276000124010200FFFE871930590000
Version ..........: 2.0
Manufacturer .....: unmanaged S/N range
Serial number ....: 87193059
Name of cardholder: Yutaka Niibe
Language prefs ...: ja
Sex ..............: male
URL of public key : http://www.gniibe.org/gniibe-20150813.asc
Login data .......: gniibe
Signature PIN ....: not forced
Key attributes ...: ed25519 cv25519 ed25519
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: 249C B377 1750 745D 5CDD 323C E267 B052 364F 028D
created ....: 2015-08-12 07:10:48
Encryption key....: E228 AB42 0F73 3B1D 712D E50C 850A F040 D619 F240
created ....: 2015-08-12 07:10:48
Authentication key: E63F 31E6 F203 20B5 D796 D266 5F91 0521 FAA8 05B1
created ....: 2015-08-12 07:16:14
General key info..: [none]
gpg/card>
Here, the secret key references (to the token) are created under .gnupg/private-keys-v1.d directory. It can be also created when I do --card-status by GnuPG.
Still, it says that there is no key info related to this token on my PC ([none] for General key info), because I don’t have the public key on this PC yet.
So, I fetch the public key from URL specified in the Token.
gpg/card> fetch
gpg: requesting key E267B052364F028D from http server www.gniibe.org
gpg: key E267B052364F028D: public key "NIIBE Yutaka <gniibe@fsij.org>" imported
gpg: Total number processed: 1
gpg: imported: 1
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 6 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 6u
gpg/card>
Good. The public key is now under .gnupg directory. We can examine by gpg --list-keys.
When I type return at the gpg/card> prompt, now, I can see:
Reader ...........: 234B:0000:FSIJ-1.2.0-87193059:0
Application ID ...: D276000124010200FFFE871930590000
Version ..........: 2.0
Manufacturer .....: unmanaged S/N range
Serial number ....: 87193059
Name of cardholder: Yutaka Niibe
Language prefs ...: ja
Sex ..............: male
URL of public key : http://www.gniibe.org/gniibe-20150813.asc
Login data .......: gniibe
Signature PIN ....: not forced
Key attributes ...: ed25519 cv25519 ed25519
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: 249C B377 1750 745D 5CDD 323C E267 B052 364F 028D
created ....: 2015-08-12 07:10:48
Encryption key....: E228 AB42 0F73 3B1D 712D E50C 850A F040 D619 F240
created ....: 2015-08-12 07:10:48
Authentication key: E63F 31E6 F203 20B5 D796 D266 5F91 0521 FAA8 05B1
created ....: 2015-08-12 07:16:14
General key info..: pub ed25519/E267B052364F028D 2015-08-12 NIIBE Yutaka <gniibe@fsij.org>
sec> ed25519/E267B052364F028D created: 2015-08-12 expires: never
card-no: FFFE 87193059
ssb> cv25519/850AF040D619F240 created: 2015-08-12 expires: never
card-no: FFFE 87193059
ssb> ed25519/5F910521FAA805B1 created: 2015-08-12 expires: never
card-no: FFFE 87193059
gpg/card>
Note that, it displays the information about “General key info”.
OK, now I can use the Token on this computer.
Update trustdb for the key on Gnuk Token¶
Yes, I can use the Token by the public key and the secret key references to the card. More, I need to update the trustdb.
To do that, I do:
$ ./gpg --edit-key E267B052364F028D
gpg (GnuPG) 2.1.13; Copyright (C) 2016 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Secret key is available.
sec ed25519/E267B052364F028D
created: 2015-08-12 expires: never usage: SC
card-no: FFFE 87193059
trust: unknown validity: unknown
ssb cv25519/850AF040D619F240
created: 2015-08-12 expires: never usage: E
card-no: FFFE 87193059
ssb ed25519/5F910521FAA805B1
created: 2015-08-12 expires: never usage: A
card-no: FFFE 87193059
[ unknown] (1). NIIBE Yutaka <gniibe@fsij.org>
[ unknown] (2) NIIBE Yutaka <gniibe@debian.org>
See, the key is unknown state. Add trust for that, because it’s the key under my control.
gpg> trust
sec ed25519/E267B052364F028D
created: 2015-08-12 expires: never usage: SC
card-no: FFFE 87193059
trust: unknown validity: unknown
ssb cv25519/850AF040D619F240
created: 2015-08-12 expires: never usage: E
card-no: FFFE 87193059
ssb ed25519/5F910521FAA805B1
created: 2015-08-12 expires: never usage: A
card-no: FFFE 87193059
[ unknown] (1). NIIBE Yutaka <gniibe@fsij.org>
[ unknown] (2) NIIBE Yutaka <gniibe@debian.org>
Please decide how far you trust this user to correctly verify other users' keys
(by looking at passports, checking fingerprints from different sources, etc.)
1 = I don't know or won't say
2 = I do NOT trust
3 = I trust marginally
4 = I trust fully
5 = I trust ultimately
m = back to the main menu
Your decision? 5
Do you really want to set this key to ultimate trust? (y/N) y
sec ed25519/E267B052364F028D
created: 2015-08-12 expires: never usage: SC
card-no: FFFE 87193059
trust: ultimate validity: unknown
ssb cv25519/850AF040D619F240
created: 2015-08-12 expires: never usage: E
card-no: FFFE 87193059
ssb ed25519/5F910521FAA805B1
created: 2015-08-12 expires: never usage: A
card-no: FFFE 87193059
[ unknown] (1). NIIBE Yutaka <gniibe@fsij.org>
[ unknown] (2) NIIBE Yutaka <gniibe@debian.org>
Please note that the shown key validity is not necessarily correct
unless you restart the program.
gpg>
And I quit from gpg. Then, when I invoke GnuPG, it will be ultimate key. Let’s see:
$ ./gpg --edit-key E267B052364F028D
gpg (GnuPG) 2.1.13; Copyright (C) 2016 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Secret key is available.
gpg: checking the trustdb
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 7 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 7u
sec ed25519/E267B052364F028D
created: 2015-08-12 expires: never usage: SC
card-no: FFFE 87193059
trust: ultimate validity: ultimate
ssb cv25519/850AF040D619F240
created: 2015-08-12 expires: never usage: E
card-no: FFFE 87193059
ssb ed25519/5F910521FAA805B1
created: 2015-08-12 expires: never usage: A
card-no: FFFE 87193059
[ultimate] (1). NIIBE Yutaka <gniibe@fsij.org>
[ultimate] (2) NIIBE Yutaka <gniibe@debian.org>
gpg> quit
$
OK, all set. I’m ready to use my Gnuk Token on this PC.