Waterboarding definitely is, according to the American Convention on Human Rights, to which the US is a signatory: http://www.oas.org/dil/treaties_B-32_American_Convention_on_...

It's article 5.2, sandwiched in-between 'you have the right not to be murdered' and 'you have the right not to be enslaved'.

Article 11 is fairly wishy-washy, but it states that privacy is also considered a human right.