A wireless device includes a data capture system, a radiant-energy data transmission system, and a steganographic encoder that hides a plural-bit auxiliary code within data captured by the data capture system prior to its transmission by the data transmission system. An illustrative system, operable with audio input data, is a cell phone that steganographically encodes a user's voice. In some arrangements the steganographic encoding depends on data wirelessly received from a remote location. A variety of other arrangements and systems are also detailed.