Round Function
Let I = (kjm,i + P) ROTL kjr,i where j is the quad-round number and i is the sub round number(0,1,2, or 3)
First Round Function f1
- O=((S1[Ia] xor S2[Ib]) - S3[Ic]) + S4[Id]
Second Round Function f2
- O=((S1[Ia] - S2[Ib]) + S3[Ic]) xor S4[Id]
Third Round Function f3
- O=((S1[Ia] + S2[Ib]) xor S3[Ic]) - S4[Id]