Better backup and testing instructions

pull/109/head
drduh 2019-05-18 17:47:13 -07:00
parent a6bc874713
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README.md
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@ -29,15 +29,11 @@ If you have a comment or suggestion, please open an [issue](https://github.com/d
* [Encryption](#encryption-1)
* [Authentication](#authentication-1)
- [Verify card](#verify-card)
- [Export public key](#export-public-key)
- [Cleanup](#cleanup)
- [Using keys](#using-keys)
- [Import public key](#import-public-key)
* [Trust master key](#trust-master-key)
- [Insert YubiKey](#insert-yubikey)
- [Encryption](#encryption-2)
- [Decryption](#decryption)
- [Signing](#signing-2)
- [Verifying signature](#verifying-signature)
- [SSH](#ssh)
* [Create configuration](#create-configuration)
@ -64,70 +60,133 @@ If you have a comment or suggestion, please open an [issue](https://github.com/d
All YubiKeys except the blue "security key" model are compatible with this guide. NEO models are limited to 2048-bit RSA keys. See [Compare YubiKeys](https://www.yubico.com/products/yubikey-hardware/compare-yubikeys/).
Consider purchasing a pair of YubiKeys, programming both, and storing one in a safe secondary location, in case of loss or damage to the first key.
You will also need several small storage devices for booting a live image, creating backups of private and public keys.
# Verify YubiKey
To confirm your YubiKey is genuine open a [browser with U2F support](https://support.yubico.com/support/solutions/articles/15000009591-how-to-confirm-your-yubico-device-is-genuine-with-u2f) and go to [https://www.yubico.com/genuine/](https://www.yubico.com/genuine/). Insert your Yubico device, and click `Verify Device` to begin the process. Touch the YubiKey when prompted, and if asked, allow it to see the make and model of the device. If you see `Verification complete`, your device is authentic.
To confirm your YubiKey is genuine, open a [browser with U2F support](https://support.yubico.com/support/solutions/articles/15000009591-how-to-confirm-your-yubico-device-is-genuine-with-u2f) to [https://www.yubico.com/genuine/](https://www.yubico.com/genuine/). Insert your Yubico device, and select Verify Device` to begin the process. Touch the YubiKey when prompted, and if asked, allow it to see the make and model of the device. If you see `Verification complete`, your device is authentic.
This website verifies the YubiKey's device attestation certificates signed by a set of Yubico CAs, and helps mitigate [supply chain attacks](https://media.defcon.org/DEF%20CON%2025/DEF%20CON%2025%20presentations/DEFCON-25-r00killah-and-securelyfitz-Secure-Tokin-and-Doobiekeys.pdf).
# Live image
It is recommended to generate cryptographic keys and configure YubiKey from a secure environment to minimize exposure. One way to do that is by downloading and booting to a [Debian Live](https://www.debian.org/CD/live/) or [Tails](https://tails.boum.org/index.en.html) image loaded from a USB drive into memory.
It is recommended to generate cryptographic keys and configure YubiKey from a secure operating system and ephemeral environment, such as [Debian Live](https://www.debian.org/CD/live/) or [Tails](https://tails.boum.org/index.en.html).
Download the latest image and verify its integrity:
To use Debian, download the latest live image:
```console
$ curl -LfO https://cdimage.debian.org/debian-cd/current-live/amd64/iso-hybrid/debian-live-9.9.0-amd64-xfce.iso
$ curl -LfO https://cdimage.debian.org/debian-cd/current-live/amd64/iso-hybrid/SHA512SUMS
$ curl -LfO https://cdimage.debian.org/debian-cd/current-live/amd64/iso-hybrid/SHA512SUMS.sign
```
Verify file integrity with GPG:
```console
$ gpg --verify SHA512SUMS.sign SHA512SUMS
gpg: Signature made Sat Apr 27 11:46:08 2019 PDT
gpg: using RSA key DF9B9C49EAA9298432589D76DA87E80D6294BE9B
gpg: Can't check signature: No public key
$ gpg --recv DF9B9C49EAA9298432589D76DA87E80D6294BE9B
gpg: key 0xDA87E80D6294BE9B: 61 signatures not checked due to missing keys
gpg: key 0xDA87E80D6294BE9B: public key "Debian CD signing key <debian-cd@lists.debian.org>" imported
gpg: marginals needed: 3 completes needed: 1 trust model: pgp
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: Total number processed: 1
gpg: imported: 1
$ gpg --verify SHA512SUMS.sign SHA512SUMS
[...]
gpg: Signature made Sat Apr 27 11:46:08 2019 PDT
gpg: using RSA key DF9B9C49EAA9298432589D76DA87E80D6294BE9B
gpg: Good signature from "Debian CD signing key <debian-cd@lists.debian.org>" [unknown]
[...]
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: DF9B 9C49 EAA9 2984 3258 9D76 DA87 E80D 6294 BE9B
$ grep $(sha512sum debian-live-9.9.0-amd64-xfce.iso) SHA512SUMS
SHA512SUMS:ae064cc399126214e4aa165fdbf9659047dd2af2d3b0ca57dd5f2686d1d3730019cfe3c56ac48db2af56eb856dbca75e642fadf56bc04c538b44d3d3a2982283 debian-live-9.9.0-amd64-xfce.iso
```
Mount a USB disk and copy the image over to it:
If the key cannot be received, try changing your DNS resolver and/or specific keyserver:
```console
$ sudo dd if=debian-live-9.9.0-amd64-xfce.iso of=/dev/sdc bs=4M && sync
$ gpg --keyserver hkps://keyserver.ubuntu.com:443 --recv DF9B9C49EAA9298432589D76DA87E80D6294BE9B
```
Mount a storage device and copy the image to it:
**Linux**
```console
$ sudo dmesg | tail
usb-storage 3-2:1.0: USB Mass Storage device detected
scsi host2: usb-storage 3-2:1.0
scsi 2:0:0:0: Direct-Access TS-RDF5 SD Transcend TS3A PQ: 0 ANSI: 6
sd 2:0:0:0: Attached scsi generic sg1 type 0
sd 2:0:0:0: [sdb] 31116288 512-byte logical blocks: (15.9 GB/14.8 GiB)
sd 2:0:0:0: [sdb] Write Protect is off
sd 2:0:0:0: [sdb] Mode Sense: 23 00 00 00
sd 2:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
sdb: sdb1 sdb2
sd 2:0:0:0: [sdb] Attached SCSI removable disk
$ sudo dd if=debian-live-9.9.0-amd64-xfce.iso of=/dev/sdb bs=4M
465+1 records in
465+1 records out
1951432704 bytes (2.0 GB, 1.8 GiB) copied, 42.8543 s, 45.5 MB/s
```
**OpenBSD**
```console
$ dmesg | tail -n2
sd2 at scsibus4 targ 1 lun 0: <TS-RDF5, SD Transcend, TS3A> SCSI4 0/direct removable serial.0000000000000
sd2: 15193MB, 512 bytes/sector, 31116288 sectors
$ doas dd if=debian-live-9.9.0-amd64-xfce.iso of=/dev/rsd2c bs=4m
465+1 records in
465+1 records out
1951432704 bytes transferred in 139.125 secs (14026448 bytes/sec)
```
Shut down the computer and disconnect any hard drives and unnecessary peripheral devices.
Plug in the USB disk and boot to the live image. Configure networking to continue. If the screen locks, unlock with user/live.
Consider using secure hardware like a ThinkPad X230 running [Coreboot](https://www.coreboot.org/) and cleaned of [Intel ME](https://github.com/corna/me_cleaner).
# Required software
Install several packages required for the following steps:
Boot the live image and configure networking.
**Note** If the screen locks, unlock with credentials: user/live.
Open the terminal and install several required packages:
**Debian/Ubuntu**
```console
$ sudo apt-get update && sudo apt-get install -y \
curl gnupg2 gnupg-agent \
cryptsetup scdaemon pcscd \
yubikey-personalization \
dirmngr \
secure-delete \
hopenpgp-tools
curl gnupg2 gnupg-agent dirmngr \
cryptsetup scdaemon pcscd \
yubikey-personalization \
secure-delete hopenpgp-tools
```
**Arch Linux**
**Arch**
```console
$ sudo pacman -Syu gnupg2 pcsclite ccid yubikey-personalization hopenpgp-tools
$ sudo pacman -Syu \
gnupg2 pcsclite ccid \
yubikey-personalization hopenpgp-tools
```
**RHEL7**
```console
$ sudo yum install -y gnupg2 pinentry-curses pcsc-lite pcsc-lite-libs gnupg2-smime
$ sudo yum install -y \
gnupg2 pinentry-curses pcsc-lite pcsc-lite-libs gnupg2-smime
```
**OpenBSD**
@ -148,55 +207,60 @@ $ brew install gnupg yubikey-personalization hopenpgp-tools ykman pinentry-mac
Download and install [Gpg4Win](https://www.gpg4win.org/) and [PuTTY](https://putty.org).
**Note** You may also need more recent versions of [yubikey-personalization](https://developers.yubico.com/yubikey-personalization/Releases/) and [yubico-c](https://developers.yubico.com/yubico-c/Releases/).
You may also need more recent versions of [yubikey-personalization](https://developers.yubico.com/yubikey-personalization/Releases/) and [yubico-c](https://developers.yubico.com/yubico-c/Releases/).
## Entropy
Generating keys will require a lot of randomness. To check the available bits of entropy available on Linux:
Generating cryptographic keys requires high-quality [randomness](https://www.random.org/randomness/), measured as entropy.
To check the available entropy available on Linux:
```console
$ cat /proc/sys/kernel/random/entropy_avail
849
```
**Optional** A hardware random number generator like [OneRNG](http://onerng.info/onerng/) will increase the speed of entropy generation and possibly its quality. To install and configure OneRNG:
Most operating systems use software-based pseudorandom number generators. A hardware random number generator like [OneRNG](http://onerng.info/onerng/) will [increase the speed](https://lwn.net/Articles/648550/) of entropy generation and possibly the quality.
Plug in the device, then install and configure OneRNG software:
```console
$ sudo apt-get install -y rng-tools at python-gnupg openssl
$ sudo apt-get install -y \
at rng-tools python-gnupg openssl
$ curl -LfO https://github.com/OneRNG/onerng.github.io/raw/master/sw/onerng_3.6-1_all.deb
$ sha256sum onerng_3.6-1_all.deb
a9ccf7b04ee317dbfc91518542301e2d60ebe205d38e80563f29aac7cd845ccb
a9ccf7b04ee317dbfc91518542301e2d60ebe205d38e80563f29aac7cd845ccb onerng_3.6-1_all.deb
$ sudo dpkg -i onerng_3.6-1_all.deb
$ echo "HRNGDEVICE=/dev/ttyACM0" | sudo tee /etc/default/rng-tools
$ sudo atd
$ sudo service rng-tools restart
```
If the service fails to start, kick off `atd` and try again:
```console
$ sudo atd ; sudo service rng-tools restart
```
Plug in the OneRNG and empty `/dev/random` - the light on the device should dim briefly. Verify the available entropy pool is re-seeded.
Test by emptying `/dev/random` - the light on the device should dim briefly:
```console
$ cat /dev/random >/dev/null
[Control-C]
[Press Control-C]
```
Verify the available entropy pool is re-seeded:
```console
$ cat /proc/sys/kernel/random/entropy_avail
3049
```
An entropy pool value greater than 3000 is sufficient.
An entropy pool value greater than 2000 is sufficient.
# Creating keys
Create a temporary directory which will be deleted on [reboot](https://en.wikipedia.org/wiki/Tmpfs):
Create a temporary directory which will be cleared on [reboot](https://en.wikipedia.org/wiki/Tmpfs):
```console
$ export GNUPGHOME=$(mktemp -d) ; echo $GNUPGHOME
@ -234,7 +298,9 @@ Disable networking for the remainder of the setup.
# Master key
The first key to generate is the master key. It will be used for certification only - to issue subkeys that are used for encryption, signing and authentication. This master key should be kept offline at all times and only accessed to revoke or issue new subkeys.
The first key to generate is the master key. It will be used for certification only: to issue subkeys that are used for encryption, signing and authentication.
**Important** The master key should be kept offline at all times and only accessed to revoke or issue new subkeys.
You'll be prompted to enter and verify a passphrase - keep it handy as you'll need it throughout. To generate a strong passphrase which could be written down in a hidden or secure place; or memorized:
@ -243,7 +309,11 @@ $ gpg --gen-random -a 0 24
ydOmByxmDe63u7gqx2XI9eDgpvJwibNH
```
Generate a new key with GPG, selecting `(8) RSA (set your own capabilities)`, `Certify`-only and `4096` bit keysize. Do not set the key to expire - see [Note #3](#notes).
On Linux, select the password with your mouse to copy it to the clipboard and paste using the middle mouse button or `Shift`-`Insert`.
Generate a new key with GPG, selecting `(8) RSA (set your own capabilities)`, `Certify` capability only and `4096` bit key size.
Do not set the master key to expire - see [Note #3](#notes).
```console
$ gpg --expert --full-generate-key
@ -302,7 +372,11 @@ Please specify how long the key should be valid.
Key is valid for? (0) 0
Key does not expire at all
Is this correct? (y/N) y
```
Select a name and email address - neither has to be valid nor existing.
```console
GnuPG needs to construct a user ID to identify your key.
Real name: Dr Duh
@ -317,21 +391,18 @@ 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.
gpg: /tmp.FLZC0xcM/trustdb.gpg: trustdb created
gpg: key 0xFF3E7D88647EBCDB marked as ultimately trusted
gpg: directory '/tmp.FLZC0xcM/openpgp-revocs.d' created
gpg: revocation certificate stored as '/tmp.FLZC0xcM/openpgp-revocs.d/011CE16BD45B27A55BA8776DFF3E7D88647EBCDB.rev'
public and secret key created and signed.
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.
pub rsa4096/0xFF3E7D88647EBCDB 2017-10-09 [C]
Key fingerprint = 011C E16B D45B 27A5 5BA8 776D FF3E 7D88 647E BCDB
uid Dr Duh <doc@duh.to>
```
As of GPG [version 2.1](https://www.gnupg.org/faq/whats-new-in-2.1.html#autorev), a revocation certificate is automatically generated at this time.
Export the key ID as a [variable](https://stackoverflow.com/questions/1158091/defining-a-variable-with-or-without-export/1158231#1158231) (`KEYID`) for use later:
```console
@ -340,7 +411,7 @@ $ export KEYID=0xFF3E7D88647EBCDB
# Subkeys
Edit the Master key to add subkeys:
Edit the master key to add sub-keys:
```console
$ gpg --expert --edit-key $KEYID
@ -353,9 +424,9 @@ sec rsa4096/0xEA5DE91459B80592
[ultimate] (1). Dr Duh <doc@duh.to>
```
Use 4096-bit keysize - or 2048-bit on NEO.
Use 4096-bit key sizes.
Use a 1 year expiration - it can always be renewed using the offline Master certification key.
Use a 1 year or shorter expiration - keys can always be renewed using the offline master key.
## Signing
@ -557,9 +628,9 @@ ssb rsa4096/0x5912A795E90DD2CF 2017-10-09 [E] [expires: 2018-10-09]
ssb rsa4096/0x3F29127E79649A3D 2017-10-09 [A] [expires: 2018-10-09]
```
**Optional** Add any additional identities or email addresses now using the `adduid` command.
Add any additional identities or email addresses you wish to associate using the `adduid` command.
To verify with OpenPGP key checks, use the automated [key best practice checker](https://riseup.net/en/security/message-security/openpgp/best-practices#openpgp-key-checks):
**Optional** Verify with OpenPGP key checks, use the automated [key best practice checker](https://riseup.net/en/security/message-security/openpgp/best-practices#openpgp-key-checks):
```console
$ gpg --export $KEYID | hokey lint
@ -571,7 +642,7 @@ The output will display any problems with your key in red text. If everything is
# Export keys
The Master and subkeys will be encrypted with your passphrase when exported.
The master key and sub-keys will be encrypted with your passphrase when exported.
Save a copy of your keys:
@ -591,41 +662,37 @@ $ gpg --armor --export-secret-subkeys $KEYID -o \path\to\dir\sub.gpg
# Backup keys
Once GPG keys are moved to YubiKey, they cannot be extracted again!
Make sure you have made an **encrypted** backup before proceeding. An encrypted USB drive or container can be made using [VeraCrypt](https://www.veracrypt.fr/en/Downloads.html).
Also consider using a [paper copy](https://www.jabberwocky.com/software/paperkey/) of the keys as an additional backup measure.
Once GPG keys are moved to YubiKey, they cannot be moved again! Create an **encrypted** backup of the keyring and consider using a [paper copy](https://www.jabberwocky.com/software/paperkey/) of the keys as an additional backup.
**Linux**
Attach a USB disk and check its label:
Attach another external storage device and check its label:
```console
$ sudo dmesg | tail
scsi8 : usb-storage 2-1:1.0
usbcore: registered new interface driver usb-storage
scsi 8:0:0:0: USB 0: 0 ANSI: 6
sd 8:0:0:0: Attached scsi generic sg4 type 0
sd 8:0:0:0: [sde] 62980096 512-byte logical blocks: (32.2 GB/30.0 GiB)
sd 8:0:0:0: [sde] Write Protect is off
sd 8:0:0:0: [sde] Mode Sense: 43 00 00 00
sd 8:0:0:0: [sde] Attached SCSI removable disk
usb-storage 4-2:1.0: USB Mass Storage device detected
scsi host7: usb-storage 4-2:1.0
scsi 7:0:0:0: Direct-Access TS-RDF5 SD Transcend TS37 PQ: 0 ANSI: 6
sd 7:0:0:0: Attached scsi generic sg1 type 0
sd 7:0:0:0: [sdb] 31116288 512-byte logical blocks: (15.9 GB/14.8 GiB)
sd 7:0:0:0: [sdb] Write Protect is off
sd 7:0:0:0: [sdb] Mode Sense: 23 00 00 00
sd 7:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
sdb: sdb1
sd 7:0:0:0: [sdb] Attached SCSI removable disk
```
Check the size to make sure it's the right device:
Write it with random data to prepare for encryption:
```console
$ sudo fdisk -l /dev/sde
Disk /dev/sde: 30 GiB, 32245809152 bytes, 62980096 sectors
/dev/sde1 2048 62980095 62978048 30G 6 FAT16
$ sudo dd if=/dev/urandom of=/dev/sdb bs=4M
```
Erase and create a new partition table:
```console
$ sudo fdisk /dev/sde
Welcome to fdisk (util-linux 2.25.2).
$ sudo fdisk /dev/sdb
Welcome to fdisk (util-linux 2.29.2).
Command (m for help): o
Created a new DOS disklabel with disk identifier 0xeac7ee35.
@ -636,22 +703,22 @@ Calling ioctl() to re-read partition table.
Syncing disks.
```
Remove and reinsert the USB drive, then create a new partition, selecting defaults:
Create a new partition with a 10 Megabyte size:
```console
$ sudo fdisk /dev/sde
Welcome to fdisk (util-linux 2.25.2).
$ sudo fdisk /dev/sdb
Welcome to fdisk (util-linux 2.29.2).
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
Select (default p):
Partition number (1-4, default 1):
First sector (2048-62980095, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-62980095, default 62980095):
Last sector, +sectors or +size{K,M,G,T,P} (2048-62980095, default 62980095): +10M
Created a new partition 1 of type 'Linux' and of size 30 GiB.
Created a new partition 1 of type 'Linux' and of size 10 MiB.
Command (m for help): w
The partition table has been altered.
@ -662,11 +729,11 @@ Syncing disks.
Use [LUKS](https://askubuntu.com/questions/97196/how-secure-is-an-encrypted-luks-filesystem) to encrypt the new partition:
```console
$ sudo cryptsetup luksFormat /dev/sde1
$ sudo cryptsetup luksFormat /dev/sdb1
WARNING!
========
This will overwrite data on /dev/sde1 irrevocably.
This will overwrite data on /dev/sdb1 irrevocably.
Are you sure? (Type uppercase yes): YES
Enter passphrase:
@ -676,27 +743,24 @@ Verify passphrase:
Mount the partition:
```console
$ sudo cryptsetup luksOpen /dev/sde1 usb
Enter passphrase for /dev/sde1:
$ sudo cryptsetup luksOpen /dev/sdb1 usb
Enter passphrase for /dev/sdb1:
```
Create a filesystem:
```console
$ sudo mkfs.ext4 /dev/mapper/usb -L usb
mke2fs 1.43.4 (31-Jan-2017)
Creating filesystem with 7871744 4k blocks and 1970416 inodes
$ sudo mkfs.ext2 /dev/mapper/usb -L usb
Creating filesystem with 10240 1k blocks and 2560 inodes
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
8193
Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
```
Mount the filesystem and copy the temporary GNUPG directory:
Mount the filesystem and copy the temporary directory with the keyring:
```console
$ sudo mkdir /mnt/encrypted-usb
@ -708,14 +772,75 @@ $ sudo cp -avi $GNUPGHOME /mnt/encrypted-usb
Keep the backup mounted if you plan on setting up two or more keys as `keytocard` **will [delete](https://lists.gnupg.org/pipermail/gnupg-users/2016-July/056353.html) the local copy** on save.
Otherwise, unmount and disconnected the encrypted USB disk:
Otherwise, unmount and disconnected the encrypted volume:
```console
$ sudo umount /mnt
$ sudo umount /mnt/encrypted-usb
$ sudo cryptsetup luksClose usb
```
Create another partition to store the public key, or skip this step if you plan on uploading it to a key server.
**Important** Without the *public* key, you will not be able to use GPG to encrypt, decrypt, nor sign messages. However, you will still be able to use YubiKey for SSH authentication.
```console
$ sudo fdisk /dev/sdb
Command (m for help): n
Partition type
p primary (1 primary, 0 extended, 3 free)
e extended (container for logical partitions)
Select (default p):
Partition number (2-4, default 2):
First sector (22528-31116287, default 22528):
Last sector, +sectors or +size{K,M,G,T,P} (22528-31116287, default 31116287): +10M
Created a new partition 2 of type 'Linux' and of size 10 MiB.
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
$ sudo mkfs.ext2 /dev/sdb2
Creating filesystem with 10240 1k blocks and 2560 inodes
Superblock backups stored on blocks:
8193
Allocating group tables: done
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
$ sudo mkdir /mnt/public
$ sudo mount /dev/sdb2 /mnt/public/
$ gpg --armor --export $KEYID | sudo tee /mnt/public/$KEYID.txt
-----BEGIN PGP PUBLIC KEY BLOCK-----
[...]
```
**Windows**
```console
$ gpg --armor --export $KEYID -o \path\to\dir\pubkey.gpg
```
**Optional** Upload the public key to a [public keyserver](https://debian-administration.org/article/451/Submitting_your_GPG_key_to_a_keyserver):
```console
$ gpg --send-key $KEYID
$ gpg --keyserver pgp.mit.edu --send-key $KEYID
$ gpg --keyserver keys.gnupg.net --send-key $KEYID
$ gpg --keyserver hkps://keyserver.ubuntu.com:443 --send-key $KEYID
```
After some time, the public key will to propagate to [other](https://pgp.key-server.io/pks/lookup?search=doc%40duh.to&fingerprint=on&op=vindex) [servers](https://pgp.mit.edu/pks/lookup?search=doc%40duh.to&op=index).
**OpenBSD**
Attach a USB disk and determine its label:
@ -753,7 +878,7 @@ Re-type passphrase:
softraid0: CRYPTO volume attached as sd3
```
Make an `i` partition, then make and mount the filesystem:
Create an `i` partition, then create and mount the filesystem:
```console
$ doas fdisk -iy sd3
@ -846,7 +971,7 @@ General key info..: [none]
## Change PIN
The default PIN is `123456` and default Admin PIN (PUK) is `12345678`. CCID-mode PINs can be up to 127 ASCII characters long.
The default PIN is `123456` and default Admin PIN (PUK) is `12345678`. CCID-mode PINs can be up to 127 ASCII characters.
The Admin PIN is required for some card operations and to unblock a PIN that has been entered incorrectly more than three times. See the GnuPG documentation on [Managing PINs](https://www.gnupg.org/howtos/card-howto/en/ch03s02.html) for details.
@ -899,7 +1024,7 @@ Language preferences: en
gpg/card> login
Login data (account name): doc@duh.to
gpg/card> [Press Enter]
gpg/card> list
Application ID ...: D2760001240102010006055532110000
Version ..........: 2.1
@ -1034,7 +1159,7 @@ gpg> save
# Verify card
Verify the subkeys have moved to YubiKey as indicated by `ssb>`:
Verify the sub-keys have been moved to YubiKey as indicated by `ssb>`:
```console
$ gpg --list-secret-keys
@ -1048,42 +1173,14 @@ ssb> rsa4096/0x5912A795E90DD2CF 2017-10-09 [E] [expires: 2018-10-09]
ssb> rsa4096/0x3F29127E79649A3D 2017-10-09 [A] [expires: 2018-10-09]
```
# Export public key
Mount another USB disk to copy the *public* key, or save it somewhere where it can be easily accessed later.
**Important** Without importing the *public* key, you will not be able to use GPG to encrypt, decrypt, nor sign messages. However, you will still be able to use YubiKey for SSH authentication.
```console
$ gpg --armor --export $KEYID > /mnt/public-usb-key/pubkey.txt
```
Windows:
```console
$ gpg --armor --export $KEYID -o \path\to\dir\pubkey.gpg
```
**Optional** Upload the public key to a [public keyserver](https://debian-administration.org/article/451/Submitting_your_GPG_key_to_a_keyserver):
```console
$ gpg --send-key $KEYID
$ gpg --keyserver pgp.mit.edu --send-key $KEYID
$ gpg --keyserver keys.gnupg.net --send-key $KEYID
```
After some time, the public key will to propagate to [other](https://pgp.key-server.io/pks/lookup?search=doc%40duh.to&fingerprint=on&op=vindex) [servers](https://pgp.mit.edu/pks/lookup?search=doc%40duh.to&op=index).
# Cleanup
Ensure you have:
* Saved the Encryption, Signing and Authentication subkeys to YubiKey.
* Saved the encryption, signing and authentication sub-keys to YubiKey.
* Saved the YubiKey PINs which you changed from defaults.
* Saved the password to the Master key.
* Saved a copy of the Master key, subkeys and revocation certificates on an encrypted volume stored offline.
* Saved the password to the master key.
* Saved a copy of the master key, sub-keys and revocation certificates on an encrypted volume, to be stored offline.
* Saved the password to that encrypted volume in a separate location.
* Saved a copy of the public key somewhere easily accessible later.
@ -1105,27 +1202,23 @@ Install required programs:
```console
$ sudo apt-get update && sudo apt-get install -y \
curl gnupg2 gnupg-agent \
cryptsetup scdaemon pcscd
gnupg2 gnupg-agent scdaemon pcscd
```
Download [drduh/config/gpg.conf](https://github.com/drduh/config/blob/master/gpg.conf):
```console
$ mkdir ~/.gnupg ; curl -o ~/.gnupg/gpg.conf https://raw.githubusercontent.com/drduh/config/master/gpg.conf
$ cd ~/.gnupg ; wget https://raw.githubusercontent.com/drduh/config/master/gpg.conf
$ chmod 600 ~/.gnupg/gpg.conf
$ chmod 600 gpg.conf
```
# Import public key
To import the public key from a file on an encrypted USB disk:
To import the public key from the non-encrypted volume created earlier:
```console
$ sudo cryptsetup luksOpen /dev/sdd1 usb
Enter passphrase for /dev/sdd1:
$ sudo mount /dev/mapper/usb /mnt
$ sudo mount /dev/sdb2 /mnt
$ gpg --import /mnt/pubkey.txt
gpg: key 0xFF3E7D88647EBCDB: public key "Dr Duh <doc@duh.to>" imported
@ -1152,12 +1245,12 @@ $ sudo apt-get install -y gnupg-curl
## Trust master key
Edit the Master key to assign it ultimate trust by selecting `trust` then option `5`:
Edit the master key to assign it ultimate trust by selecting `trust` then option `5`:
```console
$ gpg --edit-key $KEYID
$ export KEYID=0xFF3E7D88647EBCDB
Secret key is available.
$ gpg --edit-key $KEYID
gpg> trust
pub 4096R/0xFF3E7D88647EBCDB created: 2016-05-24 expires: never usage: C
@ -1187,12 +1280,12 @@ sub 4096R/0x5912A795E90DD2CF created: 2017-10-09 expires: 2018-10-09 usage:
sub 4096R/0x3F29127E79649A3D created: 2017-10-09 expires: 2018-10-09 usage: A
[ unknown] (1). Dr Duh <doc@duh.to>
gpg> save
gpg> quit
```
# Insert YubiKey
Re-connect YubiKey and check the status:
Remove and re-insert the YubiKey and check the status:
```console
$ gpg --card-status
@ -1230,122 +1323,38 @@ ssb> 4096R/0x3F29127E79649A3D created: 2017-10-09 expires: 2018-10-09
**Note** If you see `General key info..: [none]` in the output instead - go back and import the public key using the previous step.
# Encryption
Encrypt a message to your own key (useful for storing passwords and other credentials):
```console
$ echo "test message string" | gpg --encrypt --armor --recipient $KEYID
-----BEGIN PGP MESSAGE-----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=pzkv
-----END PGP MESSAGE-----
$ echo "test message string" | gpg --encrypt --armor --recipient $KEYID -o encrypted.txt
```
To encrypt to multiple recipients (or to multiple keys):
```console
$ echo "test message string" | gpg --encrypt --armor --recipient $KEYID_0 --recipient $KEYID_1 --recipient $KEYID_2
-----BEGIN PGP MESSAGE-----
[...]
$ echo "test message string" | gpg --encrypt --armor --recipient $KEYID_0 --recipient $KEYID_1 --recipient $KEYID_2 -o encrypted.txt
```
# Decryption
Decrypt the message:
```console
$ 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 <doc@duh.to>"
[Press Control-D]
$ gpg --decrypt --armor cipher.txt
gpg: anonymous recipient; trying secret key 0x0000000000000000 ...
gpg: okay, we are the anonymous recipient.
gpg: encrypted with RSA key, ID 0x0000000000000000
test message string
```
# Signing
Sign a message:
```console
$ echo "test message string" | gpg --armor --clearsign --default-key 0xBECFA3C1AE191D15
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
test message string
-----BEGIN PGP SIGNATURE-----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=+ylJ
-----END PGP SIGNATURE-----
$ echo "test message string" | gpg --armor --clearsign > signed.txt
```
# Verifying signature
Verify the signature:
```console
$ gpg
gpg: Go ahead and type your message ...
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
test message string
-----BEGIN PGP SIGNATURE-----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=+ylJ
-----END PGP SIGNATURE-----
[Press Control-D]
$ gpg --verify signed.txt
gpg: Signature made Wed 25 May 2016 00:00:00 AM UTC
gpg: using RSA key 0xBECFA3C1AE191D15
gpg: Good signature from "Dr Duh <doc@duh.to>" [ultimate]
@ -1718,7 +1727,7 @@ And reload the SSH daemon (e.g., `sudo service sshd reload`).
# Notes
1. YubiKey has two configurations: one invoked with a short press, and the other with a long press. By default, the short-press mode is configured for HID OTP - a brief touch will emit an OTP string starting with `cccccccc`. If you rarely use the OTP mode, you can swap it to the second configuration via the YubiKey Personalization tool. If you *never* use OTP, you can disable it entirely using the [YubiKey Manager](https://developers.yubico.com/yubikey-manager) application (note, this not the similarly named YubiKey NEO Manager).
1. Programming YubiKey for GPG keys still lets you use its two configurations - [OTP](https://www.yubico.com/faq/what-is-a-one-time-password-otp/) and [static password](https://www.yubico.com/products/services-software/personalization-tools/static-password/) modes, for example.
1. Programming YubiKey for GPG keys still lets you use its other configurations - [U2F](https://en.wikipedia.org/wiki/Universal_2nd_Factor), [OTP](https://www.yubico.com/faq/what-is-a-one-time-password-otp/) and [static password](https://www.yubico.com/products/services-software/personalization-tools/static-password/) modes, for example.
1. Setting an expiry essentially forces you to manage your subkeys and announces to the rest of the world that you are doing so. Setting an expiry on a primary key is ineffective for protecting the key from loss - whoever has the primary key can simply extend its expiry period. Revocation certificates are [better suited](https://security.stackexchange.com/questions/14718/does-openpgp-key-expiration-add-to-security/79386#79386) for this purpose. It may be appropriate for your use case to set expiry dates on subkeys.
1. To switch between two or more identities on different keys - unplug the first key and restart gpg-agent, ssh-agent and pinentry with `pkill gpg-agent ; pkill ssh-agent ; pkill pinentry ; eval $(gpg-agent --daemon --enable-ssh-support)`, then plug in the other key and run `gpg-connect-agent updatestartuptty /bye` - then it should be ready for use.