An injection molding machine includes supporting plates, molds coupled to the supporting plates, and a coupling guide device to guide the coupling of the molds and the supporting plates. The methods involve: combining a cryptographic key with state initialization bits to generate first combination bits; producing a first keystream by performing a permutation function \u0192 using the first combination bits as inputs thereto; and using the first keystream to encrypt first data so as to produce first encrypted data. The combination of these two foot link motions permits the users feet to travel along an elliptical path of travel.