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404 lines
12 KiB
Markdown
404 lines
12 KiB
Markdown
<!--
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Title: How to create encrypted paper backup
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Description: Learn how to create encrypted paper backup.
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Author: Sun Knudsen <https://github.com/sunknudsen>
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Contributors: Sun Knudsen <https://github.com/sunknudsen>, Alex Anderson <https://github.com/Serpent27>, Nico Kaiser <https://github.com/nicokaiser>
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Reviewers:
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Publication date: 2021-02-23T21:53:38.495Z
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Listed: true
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-->
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# How to create encrypted paper backup
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## Requirements
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- [Hardened Raspberry Pi](../how-to-configure-hardened-raspberry-pi) 📦
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- Raspberry Pi OS-compatible auto-focus HD USB webcam
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- [Adafruit PiTFT monitor](https://www.adafruit.com/product/2423) (optional)
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- macOS computer
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## Caveats
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- When copy/pasting commands that start with `$`, strip out `$` as this character is not part of the command
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- When copy/pasting commands that start with `cat << "EOF"`, select all lines at once (from `cat << "EOF"` to `EOF` inclusively) as they are part of the same (single) command
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## Setup guide
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### Step 1: log in to Raspberry Pi
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Replace `10.0.1.248` with IP of Raspberry Pi.
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When asked for passphrase, enter passphrase from [step 1](#step-1-create-ssh-key-pair-on-computer).
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```shell
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ssh pi@10.0.1.248 -i ~/.ssh/pi
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```
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### Step 2 (optional): install [Adafruit PiTFT monitor](https://www.adafruit.com/product/2423) drivers and disable console auto login
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#### Install [Adafruit PiTFT monitor](https://www.adafruit.com/product/2423) drivers
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> Heads-up: don’t worry about `PITFT Failed to disable unit: Unit file fbcp.service does not exist.`.
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> Heads-up: when asked to reboot, type `n` and press enter.
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```console
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$ sudo apt update
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$ sudo apt install -y git python3-pip
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$ sudo pip3 install --upgrade adafruit-python-shell click==7.0
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$ git clone https://github.com/adafruit/Raspberry-Pi-Installer-Scripts.git
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$ cd Raspberry-Pi-Installer-Scripts
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$ sudo python3 adafruit-pitft.py --display=28c --rotation=90 --install-type=console
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$ cd ~
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$ rm -fr Raspberry-Pi-Installer-Scripts
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```
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#### Disable console auto login
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> Heads-up: when asked to reboot, select “No” and press enter.
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```shell
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sudo raspi-config
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```
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Select “System Options”, then “Boot / Auto Login”, then “Console” and finally “Finish”.
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### Step 3: configure keyboard keymap
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> Heads-up: following instructions are for [Raspberry Pi keyboard](https://www.raspberrypi.org/products/raspberry-pi-keyboard-and-hub/) (US model).
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> Heads-up: when asked to reboot, select “No” and press enter.
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```shell
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sudo raspi-config
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```
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Select “Localisation Options”, then “Keyboard”, then “Generic 105-key PC (intl.)”, then “Other”, then “English (US)”, then “English (US)”, then “The default for the keyboard layout”, then “No compose key” and finally “Finish”.
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### Step 4: install dependencies
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```console
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$ sudo apt update
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$ sudo apt install -y fim imagemagick zbar-tools
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$ pip3 install pillow qrcode --user
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$ echo -e "export GPG_TTY=\"\$(tty)\"\nexport PATH=\$PATH:/home/pi/.local/bin" >> ~/.bashrc
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$ source ~/.bashrc
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```
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### Step 5: download [bip39.txt](./bip39.txt) ([PGP signature](./bip39.txt.sig), [PGP public key](https://sunknudsen.com/sunknudsen.asc))
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```shell
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sudo curl -o /usr/local/sbin/bip39.txt https://sunknudsen.com/static/media/privacy-guides/how-to-create-encrypted-paper-backup/bip39.txt
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```
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### Step 6: download [qr-backup.sh](./qr-backup.sh) ([PGP signature](./qr-backup.sh.sig), [PGP public key](https://sunknudsen.com/sunknudsen.asc))
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```shell
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sudo curl -o /usr/local/sbin/qr-backup.sh https://sunknudsen.com/static/media/privacy-guides/how-to-create-encrypted-paper-backup/qr-backup.sh
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sudo chmod +x /usr/local/sbin/qr-backup.sh
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```
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### Step 7: download [qr-restore.sh](./qr-restore.sh) ([PGP signature](./qr-restore.sh.sig), [PGP public key](https://sunknudsen.com/sunknudsen.asc))
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```shell
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sudo curl -o /usr/local/sbin/qr-restore.sh https://sunknudsen.com/static/media/privacy-guides/how-to-create-encrypted-paper-backup/qr-restore.sh
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sudo chmod +x /usr/local/sbin/qr-restore.sh
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```
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### Step 8: download [qr-clone.sh](./qr-clone.sh) ([PGP signature](./qr-clone.sh.sig), [PGP public key](https://sunknudsen.com/sunknudsen.asc))
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```shell
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sudo curl -o /usr/local/sbin/qr-clone.sh https://sunknudsen.com/static/media/privacy-guides/how-to-create-encrypted-paper-backup/qr-clone.sh
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sudo chmod +x /usr/local/sbin/qr-clone.sh
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```
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### Step 9: download [secure-erase.sh](./secure-erase.sh) ([PGP signature](./secure-erase.sh.sig), [PGP public key](https://sunknudsen.com/sunknudsen.asc))
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```shell
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sudo curl -o /usr/local/sbin/secure-erase.sh https://sunknudsen.com/static/media/privacy-guides/how-to-create-encrypted-paper-backup/secure-erase.sh
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sudo chmod +x /usr/local/sbin/secure-erase.sh
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```
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### Step 10: make filesystem read-only
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> Heads-up: shout-out to Nico Kaiser for his amazing [guide](https://gist.github.com/nicokaiser/08aa5b7b3958f171cf61549b70e8a34b) on how to configure a read-only Raspberry Pi.
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#### Disable swap
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```shell
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sudo dphys-swapfile swapoff
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sudo dphys-swapfile uninstall
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sudo systemctl disable dphys-swapfile.service
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```
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#### Remove `dphys-swapfile` `fake-hwclock` and `logrotate`
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```shell
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sudo apt remove -y --purge dphys-swapfile fake-hwclock logrotate
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```
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#### Link `/etc/console-setup` to `/tmp/console-setup`
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```shell
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sudo mv /etc/console-setup /tmp/console-setup
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sudo ln -s /tmp/console-setup /etc/console-setup
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```
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#### Link `/etc/resolv.conf` to `/tmp/resolv.conf`
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```shell
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sudo mv /etc/resolv.conf /tmp/resolv.conf
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sudo ln -s /tmp/resolv.conf /etc/resolv.conf
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```
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#### Link `/home/pi/.gnupg` to `/tmp/pi/.gnupg`
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```shell
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mkdir -m 700 /tmp/pi
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mv /home/pi/.gnupg /tmp/pi/.gnupg
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ln -s /tmp/pi/.gnupg /home/pi/.gnupg
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```
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#### Enable `tmp.mount`
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```shell
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echo -e "D /tmp 1777 root root -\nD /tmp/console-setup 1700 root root -\nD /tmp/pi 1700 pi pi -\nD /tmp/pi/.gnupg 1700 pi pi -\nD /var/tmp 1777 root root -" | sudo tee /etc/tmpfiles.d/tmp.conf
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sudo cp /usr/share/systemd/tmp.mount /etc/systemd/system/
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sudo systemctl enable tmp.mount
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```
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#### Edit `/boot/cmdline.txt`
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```shell
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sudo cp /boot/cmdline.txt /boot/cmdline.txt.backup
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sudo sed -i 's/fsck.repair=yes/fsck.repair=skip/' /boot/cmdline.txt
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sudo sed -i '$ s/$/ noswap ro systemd.volatile=state/' /boot/cmdline.txt
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```
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#### Edit `/etc/fstab`
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```shell
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sudo cp /etc/fstab /etc/fstab.backup
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sudo sed -i -e 's/vfat\s*defaults\s/vfat defaults,ro/' /etc/fstab
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sudo sed -i -e 's/ext4\s*defaults,noatime\s/ext4 defaults,noatime,ro,noload/' /etc/fstab
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```
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#### Disable `/boot` macOS `fseventsd` logging and Spotlight indexing
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```shell
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sudo touch /boot/.metadata_never_index
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sudo mkdir -p /boot/.fseventsd
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sudo touch /boot/.fseventsd/no_log
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```
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### Step 11: disable Wi-Fi (if not using ethernet) or disconnect ethernet cable
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```shell
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echo "dtoverlay=disable-wifi" | sudo tee -a /boot/config.txt
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```
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### Step 12: reboot
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```shell
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sudo systemctl reboot
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```
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> WARNING: DO NOT CONNECT RASPBERRY PI TO NETWORK EVER AGAIN WITHOUT REINSTALLING RASPBERRY PI OS FIRST (DEVICE IS NOW "READ-ONLY" AND “COLD”).
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### Step 13 (optional): compute SHA512 hash of SD card and store in password manager (on macOS)
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Run `diskutil list` to find disk ID of SD card with “Raspberry Pi OS Lite” installed (`disk2` in the following example).
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```console
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$ diskutil list
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/dev/disk0 (internal, physical):
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#: TYPE NAME SIZE IDENTIFIER
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0: GUID_partition_scheme *500.3 GB disk0
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1: EFI EFI 209.7 MB disk0s1
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2: Apple_APFS Container disk1 500.1 GB disk0s2
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/dev/disk1 (synthesized):
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#: TYPE NAME SIZE IDENTIFIER
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0: APFS Container Scheme - +500.1 GB disk1
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Physical Store disk0s2
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1: APFS Volume Macintosh HD - Data 340.9 GB disk1s1
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2: APFS Volume Preboot 85.9 MB disk1s2
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3: APFS Volume Recovery 529.0 MB disk1s3
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4: APFS Volume VM 3.2 GB disk1s4
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5: APFS Volume Macintosh HD 11.3 GB disk1s5
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/dev/disk2 (internal, physical):
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#: TYPE NAME SIZE IDENTIFIER
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0: FDisk_partition_scheme *15.9 GB disk2
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1: Windows_FAT_32 boot 268.4 MB disk2s1
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2: Linux 15.7 GB disk2s2
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$ sudo diskutil unmountDisk /dev/diskn (if previous step fails)
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Unmount of all volumes on disk2 was successful
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$ sudo openssl dgst -sha512 /dev/rdisk2
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SHA512(/dev/rdisk3)= 353af7e9bd78d7d98875f0e2a58da3d7cdfc494f2ab5474b2ab4a8fd212ac6a37c996d54f6c650838adb61e4b30801bcf1150081f6dbb51998cf33a74fa7f0fe
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```
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👍
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---
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## Usage guide
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### Create encrypted paper backup
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> Heads-up: use `--bip39` to test secret against BIP39 [word list](https://raw.githubusercontent.com/bitcoin/bips/master/bip-0039/english.txt).
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```console
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$ qr-backup.sh --help
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Usage: qr-backup.sh [options]
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Options:
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--bip39 test secret against BIP39 word list
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-h, --help display help for command
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$ qr-backup.sh
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Format USB flash drive? (y or n)?
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y
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mkfs.fat 4.1 (2017-01-24)
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Type secret and press enter (again)
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this is a test yo
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-----BEGIN PGP MESSAGE-----
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jA0ECQMKmFCBKHBUX8z/0kUBxi8eP7LRqP0WgOF+VgTMYuvix7AMxWR/TRM+zQk/
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i9JLr52Odmxv23jEC/KfAUdigAqhs3/GJRtwWuC2IR5NzfBNvXM=
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=xkQH
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-----END PGP MESSAGE-----
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SHA512 hash: 177cc163d89498b859ce06f6f2ac1cd2f9f493b848cdf08746bfb2f4a8bf958ebb45eb70f8f20141c12aa65387ee0545b7c0757cf8d6c808e2fa449fad0e986a
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SHA512 short hash: 177cc163
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Show SHA512 hash as QR code? (y or n)?
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n
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Done
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```
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The following image is now available on USB flash drive.
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### Restore encrypted paper backup
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> Heads-up: use `--word-list` to split secret into word list.
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```console
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$ qr-restore.sh
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Usage: qr-restore.sh [options]
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Options:
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--word-list split secret into word list
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-h, --help display help for command
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$ qr-restore.sh
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Scan QR code…
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-----BEGIN PGP MESSAGE-----
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jA0ECQMKmFCBKHBUX8z/0kUBxi8eP7LRqP0WgOF+VgTMYuvix7AMxWR/TRM+zQk/
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i9JLr52Odmxv23jEC/KfAUdigAqhs3/GJRtwWuC2IR5NzfBNvXM=
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=xkQH
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-----END PGP MESSAGE-----
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SHA512 hash: 177cc163d89498b859ce06f6f2ac1cd2f9f493b848cdf08746bfb2f4a8bf958ebb45eb70f8f20141c12aa65387ee0545b7c0757cf8d6c808e2fa449fad0e986a
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SHA512 short hash: 177cc163
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Show secret? (y or n)?
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y
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gpg: AES256 encrypted data
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gpg: encrypted with 1 passphrase
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Secret: this is a test yo
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Done
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```
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### Clone encrypted paper backup
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```console
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$ qr-clone.sh --help
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Usage: qr-clone.sh [options]
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Options:
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-h, --help display help for command
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$ qr-clone.sh
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Scan QR code…
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-----BEGIN PGP MESSAGE-----
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jA0ECQMKmFCBKHBUX8z/0kUBxi8eP7LRqP0WgOF+VgTMYuvix7AMxWR/TRM+zQk/
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i9JLr52Odmxv23jEC/KfAUdigAqhs3/GJRtwWuC2IR5NzfBNvXM=
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=xkQH
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-----END PGP MESSAGE-----
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SHA512 hash: 177cc163d89498b859ce06f6f2ac1cd2f9f493b848cdf08746bfb2f4a8bf958ebb45eb70f8f20141c12aa65387ee0545b7c0757cf8d6c808e2fa449fad0e986a
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SHA512 short hash: 177cc163
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Show secret? (y or n)?
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y
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gpg: AES256 encrypted data
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gpg: encrypted with 1 passphrase
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Secret: this is a test yo
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Done
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Backing up…
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Format USB flash drive? (y or n)?
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y
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mkfs.fat 4.1 (2017-01-24)
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-----BEGIN PGP MESSAGE-----
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jA0ECQMKAWdJZylXXDf/0kUB/rRdX1+5OYVh7iwzM0julwIfDe57slc6LeGeRtDa
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KfY4QZkCrseEoZdSZd5mGYQ0ItW9exfBiXN5AU+rbEmzF6VuEWY=
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=ul1g
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-----END PGP MESSAGE-----
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SHA512 hash: 524d8219b17aad59d7cec70f901dfdd449d15f21479740b0111b621cc870e6d82f2f4a0ea8303fb478b24500195325be9c3256d4d5b19700a1cdd1329fc2c71f
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SHA512 short hash: 524d8219
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Show SHA512 hash as QR code? (y or n)?
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n
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Done
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```
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The following image is now available on USB flash drive.
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### Secure erase flash drive
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```console
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$ secure-erase.sh --help
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Usage: secure-erase.sh [options]
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Options:
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--iterations overwrite n times (defauls to 3)
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--zero overwrite with zeros to hide secure erase
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-h, --help display help for command
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$ secure-erase.sh
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Secure erase USB flash drive? (y or n)?
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y
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Erasing… (iteration 1 of 3)
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dd: error writing '/dev/sda1': No space left on device
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1868+0 records in
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1867+0 records out
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1957691392 bytes (2.0 GB, 1.8 GiB) copied, 181.888 s, 10.8 MB/s
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Erasing… (iteration 2 of 3)
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dd: error writing '/dev/sda1': No space left on device
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1868+0 records in
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1867+0 records out
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1957691392 bytes (2.0 GB, 1.8 GiB) copied, 195.606 s, 10.0 MB/s
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Erasing… (iteration 3 of 3)
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dd: error writing '/dev/sda1': No space left on device
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1868+0 records in
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1867+0 records out
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1957691392 bytes (2.0 GB, 1.8 GiB) copied, 195.558 s, 10.0 MB/s
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Done
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```
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👍
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