International Journal of Computer Science and Communication Security (IJCSCS)
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. This paper 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.