Merge pull request #501 from drduh/wip-09may25

script key generation

scripts/generate.sh

@@ -0,0 +1,172 @@
+#!/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"
+
+print_cred () {
+  # Print a credential string in red.
+  tput setaf 1 ; printf "%s\n" "${1}" ; tput sgr0
+}
+
+print_id () {
+  # Print an identity string in yellow.
+  tput setaf 3 ; printf "%s\n" "${1}" ; tput sgr0
+}
+
+get_id_label () {
+    # Returns Identity name/label.
+    printf "YubiKey User <yubikey@example.domain>"
+}
+
+get_key_type () {
+    # Returns key type and size.
+    printf "rsa4096"
+}
+
+get_key_expiration () {
+    # Returns key expiration date.
+    printf "2027-05-01"
+}
+
+get_temp_dir () {
+    # Returns temporary working directory path.
+    mktemp -d -t "$(date +%Y.%m.%d)-XXXX"
+}
+
+set_temp_dir () {
+    # Exports and switches to temporary dir.
+    export GNUPGHOME="$(get_temp_dir)"
+    cd "$GNUPGHOME" || exit 1
+    printf "set temp dir (path='%s')\n" "$(pwd)"
+}
+
+set_attrs () {
+    # Sets identity and key attributes.
+    export IDENTITY="$(get_id_label)"
+    export KEY_TYPE="$(get_key_type)"
+    export KEY_EXPIRATION="$(get_key_expiration)"
+    printf "set attributes (label='%s', type='%s', expire='%s')\n" \
+        "$IDENTITY" "$KEY_TYPE" "$KEY_EXPIRATION"
+}
+
+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  "${PASS_LENGTH:-29}"
+}
+
+set_pass () {
+    # Exports Certify and LUKS passphrases.
+    export CERTIFY_PASS="$(get_pass)"
+    export ENCRYPT_PASS="$(get_pass)"
+    printf "set passphrases (certify='%s', encrypt='%s')\n" \
+        "$CERTIFY_PASS" "$ENCRYPT_PASS"
+}
+
+gen_key_certify () {
+    # Generates Certify key with no expiration.
+    echo "$CERTIFY_PASS" | \
+        gpg --batch --passphrase-fd 0 \
+            --quick-generate-key "$IDENTITY" \
+            "$KEY_TYPE" "cert" "never"
+}
+
+set_fingerprint () {
+    # Sets Key ID and Fingerprint environment vars.
+    key_list=$(gpg --list-secret-keys --with-colons)
+    export KEY_ID=$(printf "$key_list" | awk -F: '/^sec/ { print  $5; exit }')
+    export KEY_FP=$(printf "$key_list" | awk -F: '/^fpr/ { print $10; exit }')
+    printf "got identity (fp='%s', id='%s')\n" "$KEY_FP" "$KEY_ID"
+}
+
+gen_key_subs () {
+    # Generates Subkeys with specified expiration.
+    for SUBKEY in sign encrypt auth ; do \
+        echo "$CERTIFY_PASS" | \
+            gpg --batch --passphrase-fd 0 \
+                --pinentry-mode=loopback \
+                --quick-add-key "$KEY_FP" \
+                "$KEY_TYPE" "$SUBKEY" "$KEY_EXPIRATION"
+    done
+}
+
+save_secrets () {
+    # Exports secret keys to local files.
+    export OUTPUT_CERTIFY="$GNUPGHOME/$KEY_ID-Certify.key"
+    export OUTPUT_SUBKEYS="$GNUPGHOME/$KEY_ID-Subkeys.key"
+    echo "$CERTIFY_PASS" | \
+        gpg --output "$OUTPUT_CERTIFY" \
+            --batch --pinentry-mode=loopback --passphrase-fd 0 \
+            --armor --export-secret-keys "$KEY_ID"
+    echo "$CERTIFY_PASS" | \
+        gpg --output "$OUTPUT_SUBKEYS" \
+            --batch --pinentry-mode=loopback --passphrase-fd 0 \
+            --armor --export-secret-subkeys "$KEY_ID"
+}
+
+save_pubkey () {
+    # Exports public key to local file.
+    export OUTPUT_PUBKEY="$GNUPGHOME/$KEY_ID-Public.asc"
+    gpg --output "$OUTPUT_PUBKEY" \
+        --armor --export "$KEY_ID"
+}
+
+finish () {
+    # Prints final message with id and credentials.
+    printf "\nidentity/key label:     "
+    print_id "$IDENTITY"
+    printf "key id/fingerprint:     "
+    print_id "$KEY_ID"
+    print_id "$KEY_FP"
+    printf "subkeys expiration:     "
+    print_id "$KEY_EXPIRATION"
+
+    printf "\nsecrets and pubkey:     "
+    print_id "$GNUPGHOME"
+    print_id "$OUTPUT_PUBKEY"
+
+    printf "\ncertify passphrase:     "
+    print_cred "$CERTIFY_PASS"
+    printf "encrypt passphrase:     "
+    print_cred "$ENCRYPT_PASS"
+
+    exit 0
+}
+
+# 1. Set temporary working directory for GnuPG ops.
+set_temp_dir
+
+# 2. Set identity and key attributes, such as label and type.
+set_attrs
+
+# 3. Set passphrases for identity and storage encryption.
+set_pass
+
+# 4. Generate the Certify key.
+gen_key_certify
+
+# 5. Set resulting identity fingerprint.
+set_fingerprint
+
+# 6. Generate the Subkeys.
+gen_key_subs
+
+# 7. Export Certify and Subkeys to local storage.
+save_secrets
+
+# 8. Export public key to local storage.
+save_pubkey
+
+# 9. Print results and exit.
+finish