This is a practical guide to using YubiKey as a SmartCard for storing GPG encryption and signing keys, using the YubiKey as OTP device and FIDO U2F device.
- Install required software
- Creating keys
- Create temporary working directory for GPG
- Create configuration
- Create master key
- Save Key ID
- Create revocation certificate
- Back up master key
- Create subkeys
- Check your work
- Export subkeys
- Back up everything
- Configure YubiKey
- Configure smartcard
- Transfer keys
- Check your work
- Export public key
- Finish
- Using keys
You will need to install the following software:
$ sudo apt-get install -y gnupg2 gnupg-agent pinentry-curses scdaemon pcscd yubikey-personalization libusb-1.0-0-dev
Create a directory in /tmp which won't survive a reboot:
$ export GNUPGHOME=$(mktemp -d) ; echo $GNUPGHOME
/tmp/tmp.aaiTTovYgo
Paste the following text into a terminal window to create a recommended GPG configuration:
$ cat << EOF > $GNUPGHOME/gpg.conf
use-agent
personal-cipher-preferences AES256 AES192 AES CAST5
personal-digest-preferences SHA512 SHA384 SHA256 SHA224
default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 ZLIB BZIP2 ZIP Uncompressed
cert-digest-algo SHA512
s2k-digest-algo SHA512
s2k-cipher-algo AES256
charset utf-8
fixed-list-mode
no-comments
no-emit-version
keyid-format 0xlong
list-options show-uid-validity
verify-options show-uid-validity
with-fingerprint
EOF
Generate a new key with GPG, selecting RSA (sign only) and the appropriate keysize, optionally specifying an expiry:
$ gpg --gen-key
Please select what kind of key you want:
(1) RSA and RSA (default)
(2) DSA and Elgamal
(3) DSA (sign only)
(4) RSA (sign only)
Your selection? 4
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 4096
Requested keysize is 4096 bits
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0) 0
Key does not expire at all
Is this correct? (y/N) y
You need a user ID to identify your key; the software constructs the user ID
from the Real Name, Comment and Email Address in this form:
"Heinrich Heine (Der Dichter) <[email protected]>"
Real name: Dr Duh
Email address: [email protected]
Comment:
You selected this USER-ID:
"Dr Duh <[email protected]>"
Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
You need a Passphrase to protect your secret key.
gpg: key 0xFF3E7D88647EBCDB marked as ultimately trusted
public and secret key created and signed.
gpg: checking the trustdb
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
pub 4096R/0xFF3E7D88647EBCDB 2016-05-24
Key fingerprint = 011C E16B D45B 27A5 5BA8 776D FF3E 7D88 647E BCDB
uid [ultimate] Dr Duh <[email protected]>
Note that this key cannot be used for encryption. You may want to use
the command "--edit-key" to generate a subkey for this purpose.
Keep this passphrase handy as you'll need it throughout.
Export the key ID as a variable for use throughout:
$ KEYID=0xFF3E7D88647EBCDB
Create a way to revoke your keys in case of loss or compromise, an explicit reason being optional:
$ gpg --gen-revoke $KEYID > $GNUPGHOME/revoke.txt
sec 4096R/0xFF3E7D88647EBCDB 2016-05-24 Dr Duh <[email protected]>
Create a revocation certificate for this key? (y/N) y
Please select the reason for the revocation:
0 = No reason specified
1 = Key has been compromised
2 = Key is superseded
3 = Key is no longer used
Q = Cancel
(Probably you want to select 1 here)
Your decision? 1
Enter an optional description; end it with an empty line:
>
Reason for revocation: Key has been compromised
(No description given)
Is this okay? (y/N) y
You need a passphrase to unlock the secret key for
user: "Dr Duh <[email protected]>"
4096-bit RSA key, ID 0xFF3E7D88647EBCDB, created 2016-05-24
ASCII armored output forced.
Revocation certificate created.
Please move it to a medium which you can hide away; if Mallory gets
access to this certificate he can use it to make your key unusable.
It is smart to print this certificate and store it away, just in case
your media become unreadable. But have some caution: The print system of
your machine might store the data and make it available to others!
Save a copy of the private key block:
$ gpg --armor --export-secret-keys $KEYID > $GNUPGHOME/master.key
Edit the key to add subkeys:
$ gpg --expert --edit-key $KEYID
Secret key is available.
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: ultimate validity: ultimate
[ultimate] (1). Dr Duh <[email protected]>
First, create a signing key, selecting RSA (sign only):
gpg> addkey
Key is protected.
You need a passphrase to unlock the secret key for
user: "Dr Duh <[email protected]>"
4096-bit RSA key, ID 0xFF3E7D88647EBCDB, created 2016-05-24
Please select what kind of key you want:
(3) DSA (sign only)
(4) RSA (sign only)
(5) Elgamal (encrypt only)
(6) RSA (encrypt only)
(7) DSA (set your own capabilities)
(8) RSA (set your own capabilities)
Your selection? 4
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 4096
Requested keysize is 4096 bits
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0) 0
Key does not expire at all
Is this correct? (y/N) y
Really create? (y/N) y
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
...................+++++
..+++++
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: ultimate validity: ultimate
sub 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never usage: S
[ultimate] (1). Dr Duh <[email protected]>
Next, create an encryption key, selecting RSA (encrypt only):
gpg> addkey
Key is protected.
You need a passphrase to unlock the secret key for
user: "Dr Duh <[email protected]>"
4096-bit RSA key, ID 0xFF3E7D88647EBCDB, created 2016-05-24
Please select what kind of key you want:
(3) DSA (sign only)
(4) RSA (sign only)
(5) Elgamal (encrypt only)
(6) RSA (encrypt only)
(7) DSA (set your own capabilities)
(8) RSA (set your own capabilities)
Your selection? 6
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 4096
Requested keysize is 4096 bits
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0) 0
Key does not expire at all
Is this correct? (y/N) y
Really create? (y/N) y
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
.+++++
...........+++++
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: ultimate validity: ultimate
sub 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never usage: S
sub 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never usage: E
[ultimate] (1). Dr Duh <[email protected]>
Finally, create an authentication key, selecting RSA (set your own capabilities):
gpg> addkey
Key is protected.
You need a passphrase to unlock the secret key for
user: "Dr Duh <[email protected]>"
4096-bit RSA key, ID 0xFF3E7D88647EBCDB, created 2016-05-24
Please select what kind of key you want:
(3) DSA (sign only)
(4) RSA (sign only)
(5) Elgamal (encrypt only)
(6) RSA (encrypt only)
(7) DSA (set your own capabilities)
(8) RSA (set your own capabilities)
Your selection? 8
Possible actions for a RSA key: Sign Encrypt Authenticate
Current allowed actions: Sign Encrypt
(S) Toggle the sign capability
(E) Toggle the encrypt capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? s
Possible actions for a RSA key: Sign Encrypt Authenticate
Current allowed actions: Encrypt
(S) Toggle the sign capability
(E) Toggle the encrypt capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? e
Possible actions for a RSA key: Sign Encrypt Authenticate
Current allowed actions:
(S) Toggle the sign capability
(E) Toggle the encrypt capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? a
Possible actions for a RSA key: Sign Encrypt Authenticate
Current allowed actions: Authenticate
(S) Toggle the sign capability
(E) Toggle the encrypt capability
(A) Toggle the authenticate capability
(Q) Finished
Your selection? q
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 4096
Requested keysize is 4096 bits
Please specify how long the key should be valid.
0 = key does not expire
<n> = key expires in n days
<n>w = key expires in n weeks
<n>m = key expires in n months
<n>y = key expires in n years
Key is valid for? (0) 0
Key does not expire at all
Is this correct? (y/N) y
Really create? (y/N) y
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
+++++
.....+++++
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: ultimate validity: ultimate
sub 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never usage: S
sub 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never usage: E
sub 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never usage: A
[ultimate] (1). Dr Duh <[email protected]>
gpg> save
List your new secret keys:
$ gpg --list-secret-keys
/tmp/tmp.aaiTTovYgo/secring.gpg
-------------------------------
sec 4096R/0xFF3E7D88647EBCDB 2016-05-24
Key fingerprint = 011C E16B D45B 27A5 5BA8 776D FF3E 7D88 647E BCDB
uid Dr Duh <[email protected]>
ssb 4096R/0xBECFA3C1AE191D15 2016-05-24
ssb 4096R/0x5912A795E90DD2CF 2016-05-24
ssb 4096R/0x3F29127E79649A3D 2016-05-24
Verify with OpenPGP key checks:
Use the automated key best practice checker:
$ sudo apt-get install hopenpgp-tools
$ hkt export-pubkeys $KEYID | hokey lint
The output will display any problems with your key in red text. If everything is green, your key passes each of the tests below. If it is red, your key has failed one of the tests.
Save a copy of your subkeys:
$ gpg --armor --export-secret-keys $KEYID > $GNUPGHOME/mastersub.key
$ gpg --armor --export-secret-subkeys $KEYID > $GNUPGHOME/sub.key
Once keys are moved to hardware, they cannot be extracted again (otherwise, what would be the point?), so make sure you have made an encrypted backup before proceeding.
To create an encrypted USB drive, first attach it and check its label:
$ dmesg | tail
[ 7667.607011] scsi8 : usb-storage 2-1:1.0
[ 7667.608766] usbcore: registered new interface driver usb-storage
[ 7668.874016] scsi 8:0:0:0: USB 0: 0 ANSI: 6
[ 7668.874242] sd 8:0:0:0: Attached scsi generic sg4 type 0
[ 7668.874682] sd 8:0:0:0: [sde] 62980096 512-byte logical blocks: (32.2 GB/30.0 GiB)
[ 7668.875022] sd 8:0:0:0: [sde] Write Protect is off
[ 7668.875023] sd 8:0:0:0: [sde] Mode Sense: 43 00 00 00
[ 7668.877939] sde: sde1
[ 7668.879514] sd 8:0:0:0: [sde] Attached SCSI removable disk
Check the size to make sure it's the right drive:
$ sudo fdisk -l | grep /dev/sde
Disk /dev/sde: 30 GiB, 32245809152 bytes, 62980096 sectors
/dev/sde1 2048 62980095 62978048 30G 6 FAT16
Erase and create a new partition table:
$ sudo fdisk /dev/sde
Welcome to fdisk (util-linux 2.25.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): o
Created a new DOS disklabel with disk identifier 0xeac7ee35.
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
Remove and reinsert the USB drive, then create a new partition, selecting defaults::
$ sudo fdisk /dev/sde
Welcome to fdisk (util-linux 2.25.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-62980095, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-62980095, default 62980095):
Created a new partition 1 of type 'Linux' and of size 30 GiB.
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
Use LUKS to encrypt the new partition:
$ sudo cryptsetup luksFormat /dev/sde1
WARNING!
========
This will overwrite data on /dev/sde1 irrevocably.
Are you sure? (Type uppercase yes): YES
Enter passphrase:
Verify passphrase:
Mount the partition:
$ sudo cryptsetup luksOpen /dev/sde1 encrypted-usb
Enter passphrase for /dev/sde1:
Create a filesystem:
$ sudo mkfs.ext4 /dev/mapper/encrypted-usb -L encrypted-usb
mke2fs 1.42.12 (29-Aug-2014)
Creating filesystem with 7871744 4k blocks and 1970416 inodes
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
Mount the filesystem:
$ sudo mkdir /mnt/usb
$ sudo mount /dev/mapper/encrypted-usb /mnt/usb
Finally, copy files to it:
$ sudo cp -avi $GNUPGHOME /mnt/usb
‘/tmp/tmp.aaiTTovYgo’ -> ‘/mnt/usb/tmp.aaiTTovYgo’
‘/tmp/tmp.aaiTTovYgo/revoke.txt’ -> ‘/mnt/usb/tmp.aaiTTovYgo/revoke.txt’
‘/tmp/tmp.aaiTTovYgo/gpg.conf’ -> ‘/mnt/usb/tmp.aaiTTovYgo/gpg.conf’
‘/tmp/tmp.aaiTTovYgo/trustdb.gpg’ -> ‘/mnt/usb/tmp.aaiTTovYgo/trustdb.gpg’
‘/tmp/tmp.aaiTTovYgo/random_seed’ -> ‘/mnt/usb/tmp.aaiTTovYgo/random_seed’
‘/tmp/tmp.aaiTTovYgo/master.key’ -> ‘/mnt/usb/tmp.aaiTTovYgo/master.key’
‘/tmp/tmp.aaiTTovYgo/secring.gpg’ -> ‘/mnt/usb/tmp.aaiTTovYgo/secring.gpg’
‘/tmp/tmp.aaiTTovYgo/mastersub.key’ -> ‘/mnt/usb/tmp.aaiTTovYgo/mastersub.key’
‘/tmp/tmp.aaiTTovYgo/sub.key’ -> ‘/mnt/usb/tmp.aaiTTovYgo/sub.key’
‘/tmp/tmp.aaiTTovYgo/pubring.gpg~’ -> ‘/mnt/usb/tmp.aaiTTovYgo/pubring.gpg~’
‘/tmp/tmp.aaiTTovYgo/pubring.gpg’ -> ‘/mnt/usb/tmp.aaiTTovYgo/pubring.gpg’
Make sure the correct files were copied, then unmount and disconnected the encrypted USB drive:
$ sudo umount /mnt/usb
$ sudo cryptsetup luksClose encrypted-usb
Plug in your YubiKey and configure it:
$ ykpersonalize -m86
Firmware version 4.2.7 Touch level 527 Program sequence 4
The USB mode will be set to: 0x86
Commit? (y/n) [n]: y
The -m option is the mode command. To see the different modes, enter ykpersonalize –help. Mode 86 (in hex) enables the YubiKey NEO as a composite USB device (HID + CCID + U2F) and allows OTPs to be emitted while in use as a smart card. Once you have changed the mode, you need to re-boot the YubiKey – so remove and re-insert it.
Use GPG to configure YubiKey as a smartcard:
$ gpg --card-edit
Application ID ...: D2760001240102010006055532110000
Version ..........: 2.1
Manufacturer .....: unknown
Serial number ....: 05553211
Name of cardholder: [not set]
Language prefs ...: [not set]
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [not set]
Private DO 1 .....: [not set]
Private DO 2 .....: [not set]
Signature PIN ....: not forced
Key attributes ...: 2048R 2048R 2048R
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: [none]
Encryption key....: [none]
Authentication key: [none]
General key info..: [none]
The default PIN codes are 12345678 and 123456.
gpg/card> admin
Admin commands are allowed
gpg/card> passwd
gpg: OpenPGP card no. D2760001240102010006055532110000 detected
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? 3
PIN changed.
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? 1
PIN changed.
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? q
Some fields are optional:
gpg/card> name
Cardholder's surname: Duh
Cardholder's given name: Dr
gpg/card> lang
Language preferences: en
gpg/card> login
Login data (account name): [email protected]
gpg/card> (Press Enter)
Application ID ...: D2760001240102010006055532110000
Version ..........: 2.1
Manufacturer .....: unknown
Serial number ....: 05553211
Name of cardholder: Dr Duh
Language prefs ...: en
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [email protected]
Private DO 4 .....: [not set]
Signature PIN ....: not forced
Key attributes ...: 2048R 2048R 2048R
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: [none]
Encryption key....: [none]
Authentication key: [none]
General key info..: [none]
gpg/card> quit
Transfering keys to YubiKey hardware is a one-way operation only, so make sure you've made a backup before proceeding:
$ gpg --edit-key $KEYID
Secret key is available.
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: ultimate validity: ultimate
sub 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never usage: S
sub 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never usage: E
sub 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never usage: A
[ultimate] (1). Dr Duh <[email protected]>
gpg> toggle
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
ssb 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
ssb 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
gpg> key 1
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb* 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
ssb 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
ssb 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
Move the signature key (you will be prompted for the key passphrase and admin PIN):
gpg> keytocard
Signature key ....: [none]
Encryption key....: [none]
Authentication key: [none]
Please select where to store the key:
(1) Signature key
(3) Authentication key
Your selection? 1
You need a passphrase to unlock the secret key for
user: "Dr Duh <[email protected]>"
4096-bit RSA key, ID 0xBECFA3C1AE191D15, created 2016-05-24
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb* 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
ssb 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
Type key 1 again to deselect and key 2 to select the next key:
gpg> key 1
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
ssb 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
gpg> key 2
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb* 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
ssb 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
Move the encryption key to card:
gpg> keytocard
Signature key ....: 07AA 7735 E502 C5EB E09E B8B0 BECF A3C1 AE19 1D15
Encryption key....: [none]
Authentication key: [none]
Please select where to store the key:
(2) Encryption key
Your selection? 2
You need a passphrase to unlock the secret key for
user: "Dr Duh <[email protected]>"
4096-bit RSA key, ID 0x5912A795E90DD2CF, created 2016-05-24
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb* 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
Type key 2 again to deselect and key 3 to select the next key:
gpg> key 2
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
gpg> key 3
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb* 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
(1) Dr Duh <[email protected]>
Move the authentication key to card:
gpg> keytocard
Signature key ....: 07AA 7735 E502 C5EB E09E B8B0 BECF A3C1 AE19 1D15
Encryption key....: 6F26 6F46 845B BEB8 BDF3 7E9B 5912 A795 E90D D2CF
Authentication key: [none]
Please select where to store the key:
(3) Authentication key
Your selection? 3
You need a passphrase to unlock the secret key for
user: "Dr Duh <[email protected]>"
4096-bit RSA key, ID 0x3F29127E79649A3D, created 2016-05-24
sec 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb* 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
card-no: 0006 05553211
(1) Dr Duh <[email protected]>
Save and quit:
gpg> save
ssb> indicates a stub to the private key on smartcard:
$ gpg --list-secret-keys
/tmp/tmp.aaiTTovYgo/secring.gpg
-------------------------------
sec 4096R/0xFF3E7D88647EBCDB 2016-05-24
Key fingerprint = 011C E16B D45B 27A5 5BA8 776D FF3E 7D88 647E BCDB
uid Dr Duh <[email protected]>
ssb> 4096R/0xBECFA3C1AE191D15 2016-05-24
ssb> 4096R/0x5912A795E90DD2CF 2016-05-24
ssb> 4096R/0x3F29127E79649A3D 2016-05-24
This file should be publicly shared:
$ gpg --armor --export $KEYID > /mnt/public-usb-key/pubkey.txt
Upload your public key to public keyserver and add it to the Confluence page
If all went well, you should now reboot or securely delete $GNUPGHOME.
Import it from a file:
$ gpg --import < /mnt/public-usb-key/pubkey.txt
gpg: key 0xFF3E7D88647EBCDB: public key "Dr Duh <[email protected]>" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
Check the card's status:
$ gpg --card-status
Application ID ...: D2760001240102010006055532110000
Version ..........: 2.1
Manufacturer .....: Yubico
Serial number ....: 05553211
Name of cardholder: Dr Duh
Language prefs ...: en
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [email protected]
Signature PIN ....: not forced
Key attributes ...: 4096R 4096R 4096R
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 0
Signature key ....: 07AA 7735 E502 C5EB E09E B8B0 BECF A3C1 AE19 1D15
created ....: 2016-05-24 23:22:01
Encryption key....: 6F26 6F46 845B BEB8 BDF3 7E9B 5912 A795 E90D D2CF
created ....: 2016-05-24 23:29:03
Authentication key: 82BE 7837 6A3F 2E7B E556 5E35 3F29 127E 7964 9A3D
created ....: 2016-05-24 23:36:40
General key info..: pub 4096R/0xBECFA3C1AE191D15 2016-05-24 Dr Duh <[email protected]>
sec# 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never
ssb> 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb> 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never
card-no: 0006 05553211
ssb> 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never
card-no: 0006 05553211
sec# indicates master key is not available (as it should be stored encrypted offline).
NOTE: when executing the following commands replace the 0xFF3E7D88647EBCDB with your public key's id
Edit the imported key to assign it ultimate trust:
$ gpg --edit-key 0xFF3E7D88647EBCDB
Secret key is available.
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: unknown validity: unknown
sub 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never usage: S
sub 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never usage: E
sub 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never usage: A
[ unknown] (1). Dr Duh <[email protected]>
gpg> trust
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: unknown validity: unknown
sub 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never usage: S
sub 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never usage: E
sub 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never usage: A
[ unknown] (1). Dr Duh <[email protected]>
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
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: SC
trust: ultimate validity: unknown
sub 4096R/0xBECFA3C1AE191D15 created: 2016-05-24 expires: never usage: S
sub 4096R/0x5912A795E90DD2CF created: 2016-05-24 expires: never usage: E
sub 4096R/0x3F29127E79649A3D created: 2016-05-24 expires: never usage: A
[ unknown] (1). Dr Duh <[email protected]>
Please note that the shown key validity is not necessarily correct
unless you restart the program.
gpg> quit
Encrypt some sample text:
$ echo "$(uname -a)" | gpg --encrypt --armor --recipient 0xFF3E7D88647EBCDB
-----BEGIN PGP MESSAGE-----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=pzkv
-----END PGP MESSAGE-----
Decrypt the sample text by pasting it:
$ gpg --decrypt --armor
-----BEGIN PGP MESSAGE-----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=pzkv
-----END PGP MESSAGE-----
gpg: encrypted with 4096-bit RSA key, ID 0x5912A795E90DD2CF, created
2016-05-24
"Dr Duh <[email protected]>"
(Press Control-D)
Linux workstation 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2 (2016-04-08) x86_64 GNU/Linux
Sign some sample text using the signing subkey:
$ echo "$(uname -a)" | gpg --armor --clearsign --default-key 0xBECFA3C1AE191D15
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Linux workstation 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2 (2016-04-08) x86_64 GNU/Linux
-----BEGIN PGP SIGNATURE-----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=+ylJ
-----END PGP SIGNATURE-----
Verify the previous signature:
$ gpg
gpg: Go ahead and type your message ...
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
Linux workstation 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2 (2016-04-08) x86_64 GNU/Linux
-----BEGIN PGP SIGNATURE-----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=+ylJ
-----END PGP SIGNATURE-----
(Press Control-D)
gpg: Signature made Wed 25 May 2016 00:00:00 AM UTC
gpg: using RSA key 0xBECFA3C1AE191D15
gpg: Good signature from "Dr Duh <[email protected]>" [ultimate]
Primary key fingerprint: 011C E16B D45B 27A5 5BA8 776D FF3E 7D88 647E BCDB
Subkey fingerprint: 07AA 7735 E502 C5EB E09E B8B0 BECF A3C1 AE19 1D15
Putting it all together:
$ echo "$(uname -a)" | gpg --encrypt --sign --armor --default-key 0xFF3E7D88647EBCDB --recipient 0xBECFA3C1AE191D15 | gpg --decrypt --armor
gpg: encrypted with 4096-bit RSA key, ID 0x5912A795E90DD2CF, created 2016-05-24
"Dr Duh <[email protected]>"
Linux workstation 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2 (2016-04-08) x86_64 GNU/Linux
gpg: Signature made Wed 25 May 2016 01:00:00 AM UTC
gpg: using RSA key 0xBECFA3C1AE191D15
gpg: Good signature from "Dr Duh <[email protected]>" [ultimate]
Primary key fingerprint: 011C E16B D45B 27A5 5BA8 776D FF3E 7D88 647E BCDB
Subkey fingerprint: 07AA 7735 E502 C5EB E09E B8B0 BECF A3C1 AE19 1D15
Paste the following text into a terminal window to create a recommended GPG agent configuration:
$ cat << EOF > ~/.gnupg/gpg-agent.conf
enable-ssh-support
pinentry-program /usr/bin/pinentry-curses
default-cache-ttl 60
max-cache-ttl 120
EOF
If you are using Linux on the desktop, you may want to use /usr/bin/pinentry-gnome3 to use a GUI manager.
$ pkill ssh-agent ; pkill gpg-agent ; \
eval $(gpg-agent --daemon --enable-ssh-support \
--log-file ~/.gnupg/gpg-agent.log)
There is a -L option of ssh-add that lists public key parameters of all identities currently represented by the agent. Copy and paste the following output to the server authorized_keys file, GitHub and any other service you use that requires your ssh key:
$ ssh-add -L
ssh-rsa AAAAB4NzaC1yc2EAAAADAQABAAACAz[...]zreOKM+HwpkHzcy9DQcVG2Nw== cardno:000605553211
$ ssh [email protected] -vvv
[...]
debug2: key: cardno:000605553211 (0x1234567890),
debug1: Authentications that can continue: publickey
debug3: start over, passed a different list publickey
debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: cardno:000605553211
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Server accepts key: pkalg ssh-rsa blen 535
debug2: input_userauth_pk_ok: fp e5:de:a5:74:b1:3e:96:9b:85:46:e7:28:53:b4:82:c3
debug3: sign_and_send_pubkey: RSA e5:de:a5:74:b1:3e:96:9b:85:46:e7:28:53:b4:82:c3
debug1: Authentication succeeded (publickey).
[...]