code: public static void setEncryptionKey(final String key) {
  
  		if (key == null) {
  
  			logger.info("set_encryption_key() was called with null parameter, resetting global secret key");
  
  			// reset hash
  			secretKeyHash = null;
  			return;
  		}
  
  		try {
  
  			secretKeyHash = MessageDigest.getInstance(HASH_ALGO).digest(key.getBytes("UTF-8"));
  
  		} catch (Throwable t) {
  			logger.error("Unable to set secret key: {}", t.getMessage());
  		}
  	}
docs: ----- public static methods -----