YubiKey-Guide/scripts/generate.sh
2025-05-10 16:40:00 -07:00

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#!/usr/bin/env bash
# https://github.com/drduh/YubiKey-Guide/blob/master/scripts/generate.sh
# Generates GnuPG keys and corresponding passphrases to secure them.
#set -x # uncomment to debug
set -o errtrace
set -o nounset
set -o pipefail
umask 077
export LC_ALL="C"
get_temp_dir () {
# Returns temporary working directory path.
mktemp -d -t $(date +%Y.%m.%d)-XXXX
}
get_id_label () {
# Returns Identity name/label.
printf "YubiKey User <yubikey@example.domain>"
}
export GNUPGHOME="$(get_temp_dir)"
cd "$GNUPGHOME"
printf "set temp dir (path=%s)\n" "$(pwd)"
export IDENTITY="$(get_id_label)"
printf "set id (label=%s)\n" "$IDENTITY"
export KEY_TYPE="rsa4096"
export KEY_EXPIRATION="2027-05-01"
get_pass () {
# Returns random passphrase.
tr -dc "A-Z2-9" < /dev/urandom | \
tr -d "IOUS5" | \
fold -w ${PASS_GROUPSIZE:-4} | \
paste -sd ${PASS_DELIMITER:--} - | \
head -c ${PASS_LENGTH:-29}
}
export CERTIFY_PASS="$(get_pass)"
gen_key_certify () {
# Generates Certify key with no expiration.
echo "$CERTIFY_PASS" | \
gpg --batch --passphrase-fd 0 \
--quick-generate-key "$IDENTITY" \
"$KEY_TYPE" "cert" "never"
}
set_key_id_fp () {
# Sets Key ID and Fingerprint environment vars.
export KEYID=$(gpg -k --with-colons "$IDENTITY" | \
awk -F: '/^pub:/ { print $5; exit }')
export KEYFP=$(gpg -k --with-colons "$IDENTITY" | \
awk -F: '/^fpr:/ { print $10; exit }')
}
gen_key_certify
set_key_id_fp
printf "\nKey ID: %40s\nKey FP: %40s\n\n" "$KEYID" "$KEYFP"
gen_key_subs () {
# Generates Subkeys with specified expiration.
for SUBKEY in sign encrypt auth ; do \
echo "$CERTIFY_PASS" | \
gpg --batch --passphrase-fd 0 \
--pinentry-mode=loopback \
--quick-add-key "$KEYFP" \
"$KEY_TYPE" "$SUBKEY" "$KEY_EXPIRATION"
done
}
gen_key_subs
list_keys () {
# Prints available secret keys.
gpg --list-secret-keys
}
save_secrets () {
# Exports secret keys to local files.
echo "$CERTIFY_PASS" | \
gpg --output $GNUPGHOME/$KEYID-Certify.key \
--batch --pinentry-mode=loopback --passphrase-fd 0 \
--armor --export-secret-keys $KEYID
echo "$CERTIFY_PASS" | \
gpg --output $GNUPGHOME/$KEYID-Subkeys.key \
--batch --pinentry-mode=loopback --passphrase-fd 0 \
--armor --export-secret-subkeys $KEYID
}
save_pubkey () {
# Exports public key to local file.
gpg --output $GNUPGHOME/$KEYID-$(date +%F).asc \
--armor --export $KEYID
}
list_keys
save_secrets
save_pubkey
printf "CERTIFY PASS: \n$CERTIFY_PASS\n\n"
export LUKS_PASS="$(get_pass)"
printf "LUKS PASS:\n$LUKS_PASS\n\n"