Safeguarding communication channels is required in particular in wireless networks. The use of encryption mechanisms in the form of software is limited by the required calculation and energy capacities of mobile terminals. Costs are of significance when using hardware solutions for cryptographic operations. The present invention provides an approach which simultaneously tackles all those points. It concerns a hardware accelerator for polynomial multiplication in extended Galois fields (GF), wherein the per se known Karatsuba method is iteratively applied in accordance with the invention. When using the invention the area requirement can be reduced for example from 6.2 mm2 to 2.1 mm2. The solution according to the invention also reduces the energy consumption in comparison with solutions in accordance with the state of the art by 30%.