Unbeknownst to Dr. Baltar, his lover and co-writer of the CNP turns out to be a version of the humanoid Cylon known as Number Six. Installed in the central computers of Vipers and Raptors and in the navigation computers of almost all battlestars, the CNP was more than two years in the making The Cylon infiltrator programmed backdoors into the CNP so that the Cylon attack forces could render any ships that use the operating system to shut itself down by a remote command.