A Metamorphic-Enhanced Twofish Block Cipher And Associated FPGA Implementation

The Metamorphic-Enhanced Twofish Cipher is a metamorphic cipher that uses a variable word size and variable-size user’s key. The cipher merged two ciphers by defining a new function using four bit-balanced operations. These operations are: XOR, INV, ROR, NOP for bitwise xor, invert, rotate right and no operation respectively. The new function replaces the h-function, previously used in the Twofish Cipher, and thus creating a Meta h-function. The aim of this alteration is to provide an improvement to the Twofish cipher that introduces high confusion into the enhanced Twofish without disturbing its linear and differential diffusion criteria. In this work, we discuss the Metamorphic-Enhanced Twofish Cipher and provide a Field Programmable Gate Array (FPGA) hardware implementation of the enhanced algorithm.