code: protected String getPrivateKey() throws Exception {
          String location = this.properties.getProperty(SECRET_LOCATION);
          if (StringUtils.isBlank(location)) {
              throw new DatabaseEngineException("Encryption was specified but there's no location specified for the private key.");
          }
  
          File f = new File(location);
          if (!f.canRead()) {
              throw new DatabaseEngineException("Specified file '" + location + "' does not exist or the application does not have read permissions over it.");
          }
  
          return readString(new FileInputStream(f)).trim();
      }
docs: Reads the private key from the secret location.
  
  @return A string with the private key.
  @throws Exception If something occurs while reading.