Rabbit, introduced by Boesgaard et al. (2003), is a high-speed stream cipher designed for 128-bit keys and an optional 64-bit initialization vector (IV). It operates using a state and counter vector, applying iterative transformations with XOR, bitwise rotations, and modular addition to ensure robust security without relying on S-boxes or lookup tables. This chapter proposes enhancements to Rabbit’s architecture, including modifications to the g-function, an improved counter update scheme, and a refined initialization process incorporating external pseudo-random number generators. These refinements enhance randomness and distribution properties, making Rabbit an even more secure and efficient stream cipher.