5.3. Example of a non-bijective function multiplication up to 3 � 3 ¼ 9 on the torus of size n ¼ 4

The 4-bit input is interpreted as a pair of numbers from the set 0f g ; 1; 2; 3 , whose product, the output, lies within the set 0f g ; 1; 2; 3; 4; 6; 9 .

