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https://github.com/NiklasGollenstede/nixos-installer.git
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121 lines
6.7 KiB
Bash
121 lines
6.7 KiB
Bash
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##
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# Key Generation Methods
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# See »../../modules/fs/keystore.nix.md« for more documentation.
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# It is probably generally advisable that these functions output ASCII strings.
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# Keys used as ZFS encryption keys (with the implicit »keyformat = hex«) must be 64 (lowercase?) hex digits.
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##
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## Outputs nothing (/ an empty key), causing that ZFS dataset to be unencrypted, even if it's parent is encrypted.
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function gen-key-unencrypted {( set -eu # 1: usage
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: # TODO: write-secret does not allow empty secrets anymore (might want to change that back)
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)}
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## Uses the hostname as a trivial key.
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function gen-key-hostname {( set -eu # 1: usage
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usage=$1
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if [[ ! "$usage" =~ ^(luks/keystore-@{config.networking.hostName!hashString.sha256:0:8}/.*)$ ]] ; then printf 'The trivial »hostname« key mode is only available for the keystore itself.\n' 1>&2 ; \exit 1 ; fi
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printf %s "@{config.networking.hostName}"
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)}
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## Obtains a key by reading it from a bootkey partition (see »add-bootkey-to-keydev«).
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function gen-key-usb-part {( set -eu # 1: usage
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usage=$1
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if [[ ! "$usage" =~ ^(luks/keystore-[^/]+/[1-8])$ ]] ; then printf '»usb-part« key mode is only available for the keystore itself.\n' 1>&2 ; \exit 1 ; fi
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bootkeyPartlabel=bootkey-"@{config.networking.hostName!hashString.sha256:0:8}"
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cat /dev/disk/by-partlabel/"$bootkeyPartlabel"
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)}
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## Outputs a key by simply printing an different keystore entry (that must have been generated before).
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function gen-key-copy {( set -eu # 1: _, 2: source
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source=$2
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keystore=/run/keystore-@{config.networking.hostName!hashString.sha256:0:8}
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cat "$keystore"/"$source".key
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)}
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## Outputs a key by simply using the constant »$value« passed in.
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function gen-key-constant {( set -eu # 1: _, 2: value
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value=$2
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printf %s "$value"
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)}
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## Obtains a key by prompting for a password.
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function gen-key-password {( set -eu # 1: usage
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usage=$1
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( prompt-new-password "as key »(@{config.networking.hostName}:)$usage«" || \exit 1 )
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)}
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## Generates a key by prompting for (or reusing) a »$user«'s password, combining it with »$keystore/home/$user.key«.
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function gen-key-home-composite {( set -eu # 1: usage, 2: user
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usage=$1 ; user=$2
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keystore=/run/keystore-@{config.networking.hostName!hashString.sha256:0:8}
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if [[ ${!userPasswords[@]} && ${userPasswords[$user]:-} ]] ; then
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password=${userPasswords[$user]}
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else
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password=$( prompt-new-password "for the user account »$user« (as component for key »(@{config.networking.hostName}:)$usage«)" )
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if [[ ! $password ]] ; then \exit 1 ; fi ; userPasswords[$user]=$password # TODO: won't propagate
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fi
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{ cat "$keystore"/home/"$user".key && cat <<<"$password" ; } | sha256sum | head -c 64
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)}
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## Generates a reproducible, host-independent key by challenging slot »$slot« of YubiKey »$serial« with »$user«'s password.
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function gen-key-home-yubikey {( set -eu # 1: usage, 2: serialAndSlotAndUser(as »serial:slot:user«)
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usage=$1 ; args=$2
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serial=$( <<<"$args" cut -d: -f1 ) ; slot=$( <<<"$args" cut -d: -f2 )
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user=${args#$serial:$slot:}
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if [[ ${!userPasswords[@]} && ${userPasswords[$user]:-} ]] ; then
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password=${userPasswords[$user]}
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else
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password=$( prompt-new-password "for the user account »$user« (as YubiKey challenge for key »:$usage«)" )
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if [[ ! $password ]] ; then \exit 1 ; fi ; userPasswords[$user]=$password # TODO: won't propagate
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fi
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gen-key-yubikey-challenge "$usage" "$serial:$slot:home-$user=$password" true "»${user}«'s password (to create key »:${usage}«)"
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)}
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## Generates a reproducible secret by prompting for a pin/password and then challenging slot »$slot« of YubiKey »$serial«.
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function gen-key-yubikey-pin {( set -eu # 1: usage, 2: serialAndSlot(as »serial:slot«)
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usage=$1 ; serialAndSlot=$2
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pin=$( prompt-new-password "/ pin as challenge to YubiKey »$serialAndSlot« for key »:$usage«" )
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if [[ ! $pin ]] ; then \exit 1 ; fi
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gen-key-yubikey-challenge "$usage" "$serialAndSlot:$pin" true "password / pin to create key »:$usage«"
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)}
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## Generates a reproducible secret for a certain »$use«case and optionally »$salt« specific to the current host(name) by challenging slot »$slot« of YubiKey »$serial«.
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function gen-key-yubikey {( set -eu # 1: usage, 2: serialAndSlotAndSalt(as »serial:slot:salt«)
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usage=$1 ; args=$2
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serial=$( <<<"$args" cut -d: -f1 ) ; slot=$( <<<"$args" cut -d: -f2 )
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salt=${args/$serial:$slot:/}
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usagE="$usage" ; if [[ "$usage" =~ ^(luks/.*/[0-8])$ ]] ; then usagE="${usage:0:(-2)}" ; fi # produce the same secret, regardless of the target luks slot
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challenge="@{config.networking.hostName}:$usagE${salt:+:$salt}"
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gen-key-yubikey-challenge "$usage" "$serial:$slot:$challenge" '' "challenge »"$challenge":1/2« to create key »@{config.networking.hostName}:$usage«"
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)}
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## Generates a reproducible secret by challenging slot »$slot« of YubiKey »$serial« with the fixed »$challenge«.
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function gen-key-yubikey-challenge {( set -eu # 1: _, 2: serialAndSlotAndChallenge(as »$serial:$slot:$challenge«), 3?: onlyOnce, 4?: message
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args=$2 ; onlyOnce=$3 ; message=$4
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serial=$( <<<"$args" cut -d: -f1 ) ; slot=$( <<<"$args" cut -d: -f2 )
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challenge=${args/$serial:$slot:/}
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if [[ "$serial" != "$( @{native.yubikey-personalization}/bin/ykinfo -sq 2>/dev/null )" ]] ; then printf 'Please insert / change to YubiKey with serial %s!\n' "$serial" 1>&2 ; fi
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if [[ ! $onlyOnce ]] ; then
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read -p 'Challenging YubiKey '"$serial"' slot '"$slot"' twice with '"$message"'. Enter to continue, or Ctrl+C to abort:'
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else
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read -p 'Challenging YubiKey '"$serial"' slot '"$slot"' once with '"$message"'. Enter to continue, or Ctrl+C to abort:'
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fi
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if [[ "$serial" != "$( @{native.yubikey-personalization}/bin/ykinfo -sq )" ]] ; then printf 'YubiKey with serial %s not present, aborting.\n' "$serial" 1>&2 ; \exit 1 ; fi
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if [[ ! $onlyOnce ]] ; then
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secret="$( @{native.yubikey-personalization}/bin/ykchalresp -"$slot" "$challenge":1 )""$( sleep .5 || : ; @{native.yubikey-personalization}/bin/ykchalresp -"$slot" "$challenge":2 || @{native.yubikey-personalization}/bin/ykchalresp -"$slot" "$challenge":2 )" # the second consecutive challenge tends to fail if it follows immediately
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if [[ ${#secret} != 80 ]] ; then printf 'YubiKey challenge failed, aborting.\n' "$serial" 1>&2 ; \exit 1 ; fi
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else
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secret="$( @{native.yubikey-personalization}/bin/ykchalresp -"$slot" "$challenge" )"
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if [[ ${#secret} != 40 ]] ; then printf 'YubiKey challenge failed, aborting.\n' "$serial" 1>&2 ; \exit 1 ; fi
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fi
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{ printf %s "$secret" || true ; } | head -c 64
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)}
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## Generates a random secret key.
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function gen-key-random {( set -eu # 1: usage
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</dev/urandom @{native.xxd}/bin/xxd -l 32 -c 64 -p
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)}
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