diff --git a/SM4-with-AESENCLAST.md b/SM4-with-AESENCLAST.md
index 78ab4b1..3196264 100644
--- a/SM4-with-AESENCLAST.md
+++ b/SM4-with-AESENCLAST.md
@@ -89,6 +89,28 @@ sm4_box_aesbox_4
 		x.bytes[i] = v
 	} 
 ```
+**How to calculate lookup table from M, C?**
+```
+{Mi+C | i>=0 && i<256}
+
+// Generate lookup table based on M matrix and C
+func gen_lookup_table(m [8]byte, c byte) {
+	for i := 0; i < 16; i++ {
+		for j := 0; j < 16; j++ {
+			x := ((byte(bits.OnesCount8(byte(i*16+j)&m[0])) & 1) << 7) ^
+				((byte(bits.OnesCount8(byte(i*16+j)&m[1])) & 1) << 6) ^
+				((byte(bits.OnesCount8(byte(i*16+j)&m[2])) & 1) << 5) ^
+				((byte(bits.OnesCount8(byte(i*16+j)&m[3])) & 1) << 4) ^
+				((byte(bits.OnesCount8(byte(i*16+j)&m[4])) & 1) << 3) ^
+				((byte(bits.OnesCount8(byte(i*16+j)&m[5])) & 1) << 2) ^
+				((byte(bits.OnesCount8(byte(i*16+j)&m[6])) & 1) << 1) ^
+				((byte(bits.OnesCount8(byte(i*16+j)&m[7])) & 1) << 0) ^ c
+			fmt.Printf("0x%02X, ", x)
+		}
+		fmt.Println()
+	}
+}
+```
 
 **How to calculate M, C from lookup table?**