Why did Cheney want torture formally authorized?

[mykpart]

Bear with me. According to my Vietnam veteran husband, the CIA has always routinely engaged in "enhanced interrogation," but it's done on the quiet, without authorization or acknowledgement, so that if it's discovered, the military can disavow all knowledge, kind of like on Mission Impossible. Remember on Mash the recurring character of Harry Flagg? Same thing, he was CIA, or whatever it was called in the 50s. This seems plausible to me, and if you accept the premise, then why would Cheney have wanted to have Bush sign off on torture? Could it be nothing more than ego on Cheney's part? Did he want to assert authority over the CIA? or over Bush? or have "something on" Bush? Is he really evil enough to torture people just for the sake of his ego? If true, how is he different from Saddam Hussein?