diff --git a/SM4-with-AESENCLAST.md b/SM4-with-AESENCLAST.md
index 739767e..cae4bb6 100644
--- a/SM4-with-AESENCLAST.md
+++ b/SM4-with-AESENCLAST.md
@@ -177,6 +177,11 @@ func sm4_box_aesenclast_intel(rk uint32, t0, t1, t2, t3, a1l, a1h, a2l, a2h __m1
 ```
 其实x = mm_shuffle_epi8(x, intelmaskSrows)在mm_aesenclast_si128之前调用，结果也是一样的。  
 
+类似于：  
+```
+{(M1, C1, M2, C2) | SM4-S(x) = A2(AES-S(A1(x)), A1(x) = M1*x + C1, A2(x) = M2*(x+0x63) + C2 = M2*x + M2*0x63 + C2}
+```
+
 ## How to calculate lookup table from M, C?
 $\{ M\times i + C \mid i \in [0,255] \}$