def spbox(reg, idx, t0, t1):
x = reg[idx]
y = reg[idx + 2]
z = reg[idx + 4]
ARM_m0.comment('START SPBOX')
ARM_m0.comment('rotate x <<< ' + str(R))
ARM_m0.LDI(t0, ror_r)
ARM_m0.ROR(x, t0)
ARM_m0.comment('rotate y <<< ' + str(S))
ARM_m0.LDI(t0, ror_s)
ARM_m0.ROR(y, t0)
ARM_m0.comment('compute x')
ARM_m0.MOV(t1, x)
ARM_m0.MOV(t0, z)
ARM_m0.LSL(t0, 1)
ARM_m0.MOV(x, y)
ARM_m0.AND(x, z)
ARM_m0.LSL(x, 2)
ARM_m0.EOR(x, t0)
ARM_m0.EOR(x, t1)
ARM_m0.comment('compute y')
ARM_m0.MOV(t0, y)
ARM_m0.MOV(y, t1)
ARM_m0.OR(y, z)
ARM_m0.LSL(y, 1)
ARM_m0.EOR(y, t1)
ARM_m0.EOR(y, t0)
ARM_m0.comment('compute z')
ARM_m0.AND(t1, t0)
ARM_m0.LSL(t1, 3)
ARM_m0.EOR(t0, t1)
ARM_m0.EOR(z, t0)
reg[idx], reg[idx + 4] = reg[idx + 4], reg[idx]
return reg
right = spbox(right, 0, 0, 7) right = spbox(right, 1, 0, 7) right = small_swap(right) right = spbox(right, 0, 0, 7) right = spbox(right, 1, 0, 7) right = spbox(right, 0, 0, 7) right = spbox(right, 1, 0, 7) right, left = permute(right, left) left = spbox(left, 0, 0, 7) left = spbox(left, 1, 0, 7) left = small_swap(left) load_cst(0, 24) ARM_m0.EOR(left[0], 0) # add constants left = spbox(left, 0, 0, 7) left = spbox(left, 1, 0, 7) left = spbox(left, 0, 0, 7) left = spbox(left, 1, 0, 7) # 3 rounds left, right = big_swap(left, right) left = spbox(left, 0, 0, 7) left = spbox(left, 1, 0, 7) left = spbox(left, 0, 0, 7) left = spbox(left, 1, 0, 7) left = small_swap(left) load_cst(0, 20)