We present the architecture of digit-serial normal basis multiplier over GF(2m ). The multiplier was derived from the multiplier of Agnew et al. Proposed multiplier is scalable by the digit width of general value in difference of the multiplier of Agnew et al. that may be scaled only by digit width that divides the degree m. This helps designers to trade area for speed e.g. in public-key cryptographic systems based on elliptic-curves, where m should be a prime number. Functionality of multiplier has been tested by simulation and implemented in Xilinx Virtex 4 FPGA.