Apparatus and methods are presented for using configurable additive data scrambling or descrambling circuitry for multichannel link aggregators in which a scrambler or descrambler polynomial is specified by binary data in a programmable register, and the polynomial data is used to compute a polynomial matrix. A scrambler or descrambler pattern is computed according to the polynomial matrix, and input data is bitwise exclusive-ORed with the computed scrambler or descrambler pattern to generate scrambled or descrambled output data. The scrambling or descrambling circuitry can be reconfigured for different polynomials by reprogramming the register, with the scrambler or descrambler automatically computing an updated polynomial matrix.