Federal law enforcement and national security officials are preparing to seek sweeping new regulations for the Internet, arguing that their ability to wiretap criminal and terrorism suspects is going dark" as people increasingly communicate online instead of by telephone. Essentially, officials want Congress to require all services that enable communications - including encrypted e-mail transmitters like BlackBerry, social networking Web sites like Facebook and software that allows direct "peer to peer" messaging like Skype - to be technically capable of complying if served with a wiretap order. The mandate would include being able to intercept and unscramble encrypted messages. James X. Dempsey, vice president of the Center for Democracy and Technology, an Internet policy group, said the proposal had "huge implications" and challenged "fundamental elements of the Internet revolution" - including its decentralized design. "They are really asking for the authority to redesign services that take advantage of the unique, and now pervasive, architecture of the Internet," he said. "They basically want to turn back the clock and make Internet services function the way that the telephone system used to function."