Abstract: Information science has undoubtedly engulfed the world. While astonishing on such growth, at the same time the invention of new protocols and procedures to guard the information have been going on in an effective way. Many of the transactions use images for sharing information. Image encryption needs a definite attention in such circumstances. In this study, FPGA based spatial image encryption has been proposed. The suggested approach uses variable key with Galois Field (GF) multiplier over 28 for encrypting the 128x128 image which was stored in internal memory of Cyclone II EP2C35F672C6 FPGA. A maximum of 11, 161 LEs (34% of total LEs) were consumed for encrypting one of the secret images Gandhiji on FPGA. This image encryption approach took 1.310 milliseconds for encrypting the 128x128 grayscale images. The effects of using fixed and variable keys for encryption have also been analyzed.