  In the present paper, we implement a message recovery attack to all variants
of the NTRU cryptosystem. Our approach involves a reduction from the
NTRU-lattice to a Voronoi First Kind lattice, enabling the application of a
polynomial CVP exact algorithm crucial for executing the Message Recovery. The
efficacy of our attack relies on a specific oracle that permits us to
approximate an unknown quantity. Furthermore, we outline the mathematical
conditions under which the attack is successful. Finally, we delve into a
well-established polynomial algorithm for CVP on VFK lattices and its
implementation, shedding light on its efficacy in our attack. Subsequently, we
present comprehensive experimental results on the NTRU-HPS and the NTRU-Prime
variants of the NIST submissions and propose a method that could indicate the
resistance of the NTRU cryptosystem to our attack.
