LED is an ultra-lightweight block cipher that is mainly used in devices with limited resources. Currently, the software and hardware structure of this cipher utilize a complex logic operation to generate a sequence of random numbers called round constant and this causes the algorithm to slow down and record low throughput. To improve the speed and throughput of the original algorithm, the Fast Lightweight Encryption Device (FLED) has been proposed in this paper. The key size of the currently existing LED algorithm is in 64-bit & 128-bit but this article focused mainly on the 64-bit key (block size=64-bit). In the proposed FLED design, complex operations have been replaced by LFSR left feedback technology to make the algorithm perform more efficiently and productively. The results of the cipher/decipher analysis, 15 NIST test, comparison between proposal FLED and original LED based on the results of correlation coefficient (CC)and Cosine Similarity (CS), execution time, and throughputs showed that the proposed FLED has faster cipher and more productive than the original LED; it is also more secure than the original LED.
