We present elliptic curve cryptography (ECC) coprocessor,

which is dual-field processor with projective

coordinator. We have implemented architecture for scalar

multiplication, which is key operation in elliptic curve

cryptography. Our coprocessor can be adapted both prime field

and binary field, also contains a control unit with 256 bit serial

and parallel operations , which provide integrated highthroughput

with low power consumptions. Our scalar multiplier

architecture operation is perform base on clock rate and produce

better performance in term of time and area compared to similar

works. We used Verilog for programming and synthesized using

Xilinx Vertex II Pro devices. Simulation was done with Modelsim

XE 6.1e, VLSI simulation software from Mentor Graphics

Corporation especially for Xilinx devices.