US bank Web sites will be adding additional security measures by the end of 2006 to meet new demands from federal regulators for “two-factor” authentication. That essentially means checking something more than just user name and password to verify a customer’s identity. “Phishers” and other Internet fraud artists have become adept at stealing passwords, mainly through “social engineering.” Preying on people’s propensity to believe something seemingly authoritative, criminals send authentic-looking emails that send unsuspecting people to an authentic-looking Web site where they give away their data.