US security officials have approved a high-tech, spyproof, $3,350 smartphone for Barack Obama so he can be the first sitting president to use e-mail. Media reports said the Sectera Edge, made by General Dynamics, is capable of encrypting top-secret voice conversations and handling classified documents. However, there are strict rules for both the president and those corresponding with him. First, only a select circle of friends and staff will have his address. Second, anyone placed on that exclusive list will first receive a briefing from the White House counsel's office.