Project 2 (PRESENT): Over the last few years, several new block algorithms which are classified as "lightweight ciphers" have been proposed. Lightweight commonly refers to algorithms with a very low implementation complexity, especially in hardware. Trivium is an example of a lightweight stream cipher. A promising block cipher candidate is PRESENT, which was designed specifically for applications such as RFID tags or other pervasive computing applications that are extremely power or cost constrained. (One of the book authors participated in the design of PRESENT.) plaintext key register A sBoxlayer pLayer update generateRoundKeys for i=1 to 31 do addRoundKey(STATEK) soxlayer(STATE) player' STATE) end for addRoundKey(STATE (12) sBoxlayer update player Ksz cipertext Figure 4: Internal structure and pseudocode of the block cipher PRESENT Unlike DES, PRESENT is not based on a Feistel network. Instead it is a substitution- permutation network (SP-network) and consists of 31 rounds. The block length is 64 bits, and two key lengths of 80 and 128 bits are supported. Each of the 31 rounds consists of an XOR operation to introduce a round key Ki for 1