Add automatic decrypt and restore SCB script (#1162)

scripts/backup/restore

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+UMBREL_ROOT="$(readlink -f $(dirname "${BASH_SOURCE[0]}")/../..)"
+RESTORE_ID="$RANDOM"
+
+show_help() {
+  cat << EOF
+restore 0.0.1
+
+CLI for restoring Umbrel backups (SCB). The file is decrypted if necessary.
+
+Usage: restore <path-to-backup-file>
+EOF
+}
+
+check_dependencies () {
+  for cmd in "$@"; do
+    if ! command -v "$cmd" >/dev/null 2>&1; then
+      echo "This script requires \"${cmd}\" to be installed"
+      exit 1
+    fi
+  done
+}
+
+check_dependencies openssl tar gpg
+
+# Deterministically derives 128 bits of cryptographically secure entropy
+derive_entropy () {
+  identifier="${1}"
+  umbrel_seed=$(cat "${UMBREL_ROOT}/db/umbrel-seed/seed") || true
+
+  if [[ -z "$umbrel_seed" ]] || [[ -z "$identifier" ]]; then
+    >&2 echo "Missing derivation parameter, this is unsafe, exiting."
+    exit 1
+  fi
+
+  # We need `sed 's/^.* //'` to trim the "(stdin)= " prefix from some versions of openssl
+  printf "%s" "${identifier}" | openssl dgst -sha256 -hmac "${umbrel_seed}" | sed 's/^.* //'
+}
+
+echo "Deriving keys..."
+
+backup_id=$(derive_entropy "umbrel_backup_id")
+encryption_key=$(derive_entropy "umbrel_backup_encryption_key")
+
+if [ -z ${1+x} ]; then
+  show_help
+  exit 1
+else
+  BACKUP_FILE="$1"
+fi
+
+if [[ "$BACKUP_FILE" == *.pgp ]]; then
+  echo "Backup is encrypted, decrypting backup..."
+
+  BACKUP_FOLDER_PATH="/tmp/backup-$RESTORE_ID"
+  mkdir -p "${BACKUP_FOLDER_PATH}"
+
+  cat "${BACKUP_FILE}" | gpg \
+    --batch \
+    --decrypt \
+    --passphrase "${encryption_key}" \
+    | tar \
+    --extract \
+    --verbose \
+    --gzip \
+    --directory "$BACKUP_FOLDER_PATH" \
+    || {
+      echo "Failed to decrypt backup, exiting..."
+      exit 1
+    }
+
+  BACKUP_FILE="$BACKUP_FOLDER_PATH/backup/channel.backup"
+
+  echo "Backup decrypted."
+fi
+
+BACKUP_FILE_LND="$UMBREL_ROOT/lnd/channel-$RESTORE_ID.backup"
+mv -f "$BACKUP_FILE" "$BACKUP_FILE_LND"
+
+echo "Restoring channel backup..."
+echo "This can take a while, depending on your number of channels."
+
+$UMBREL_ROOT/bin/lncli restorechanbackup --multi_file "/data/.lnd/channel-$RESTORE_ID.backup"
+
+echo "Cleaning files..."
+
+rm -Rf "$BACKUP_FOLDER_PATH" "$BACKUP_FILE_LND"
+
+echo "Done!"