Abstract: The process of RSA encryption and decryption is to perform the calculation of m e mod N. This modular multiplication can be carried out by using a w-bit multiplier （2 wN） through iteration. Pipelining is one of efficient techniques to increase the throughput for a given word long （w） multiplier. However, by using traditional multiplier, there is data dependency between iterations. To reduce the delay of data dependency, a novel multiplier, named oblong multiplier by its partial product shape is proposed. The new RSA multiplier designed based on the oblong multiplier is up to as twice as fast the traditional one. The gain in speed arises from the faster clock that results from the cut down of data dependency delay cost. The presented multiplier is only a prototype. By taking the advantage of the oblong multiplier arithmetic, a multiplier with pipeline stage at intervals of 1-bit full adder plus latch delay can be designed.