The presently claimed invention relates generally to methods and apparatus associated with steganographic encoding (e.g., data hiding). One claim recites a method including: obtaining plural-bit auxiliary information; and during communication between a first computer and a second computer over a network, modulating timing or phase of a clock signal generated by the first computer so as to steganographically hide the plural-bit auxiliary information in a communications signal sent between the first computer and the second computer. Of course, other claims and combinations are provided as well.