Methods and apparatus for scrambling and unscrambling a plurality of data streams having differing data, on a plurality of signal channels, are taught. The data streams may be television programs or other signal information, transmitted in a frame-by-frame manner with discrete synchronizing information, and where some of the data streams may be high priority such as pay-TV program material. All of the data streams are synchronized, an encryption key code is imposed on them, and a data package containing an identifier code for each data stream and a routing code is generated, so that each data stream is assigned at any instant of time to a specific one of the plurality of signal channels. The data package is encrypted in each data stream by being inserted at a specific place therein relative to the synchronizing information. At any authorized receiver the encryption key code is captured and used to decrypt the encrypted data package so as to decode the identifier and routing codes thereof, whereby a given data stream may be tracked no matter on which transmitted channel it appears at any instant of time. Several embodiments for controlling a local oscillator so as to track a given data stream, are taught.