diff --git a/src/main/java/com/sunyard/sge/database/SydApiSM4.java b/src/main/java/com/sunyard/sge/database/SydApiSM4.java
index caa62b2..13384be 100644
--- a/src/main/java/com/sunyard/sge/database/SydApiSM4.java
+++ b/src/main/java/com/sunyard/sge/database/SydApiSM4.java
@@ -21,10 +21,10 @@ public class SydApiSM4 {
         this.iKeyIndex = iKeyIndex;
     }
 
-    public void update(byte[] pcData) {
+    public byte[] update(byte[] pcData) {
         this.pcdataResult = pcData;
         if (null == pcData || pcData.length == 0) {
-            return;
+            return new byte[0];
         }
         int plength = pcData.length;
         if (is_finished) {
@@ -58,20 +58,22 @@ public class SydApiSM4 {
                 bufferResult.put(bytes1);
                 sourceWrap = bufferResult;
             }
-            byte[] bytes = api.SYD_SM4_LongData(iKeyIndex, pcdataResult, iPkgNum, iFlag);
-            iPkgNum = 2;
+             iPkgNum = 2;
+             return api.SYD_SM4_LongData(iKeyIndex, pcdataResult, iPkgNum, iFlag);
+
         } else {
             if (16 > pcData.length + sourceWrap.array().length) {
                 ByteBuffer bufferResult = ByteBuffer.allocate(sourceWrap.array().length + plength);
                 bufferResult.put(SydSM4Mac.bytebuffer2ByteArray(sourceWrap));
                 bufferResult.put(pcData);
                 sourceWrap = bufferResult;
+                return new byte[0];
             } else if ((pcData.length + sourceWrap.array().length) % 16 == 0) {
                 ByteBuffer bufferResult = ByteBuffer.allocate(sourceWrap.array().length + plength);
                 bufferResult.put(SydSM4Mac.bytebuffer2ByteArray(sourceWrap));
                 bufferResult.put(pcData);
                 byte[] bytes = SydSM4Mac.bytebuffer2ByteArray(bufferResult);
-                api.SYD_SM4_LongData(iKeyIndex, bytes, iPkgNum, iFlag);
+                return api.SYD_SM4_LongData(iKeyIndex, bytes, iPkgNum, iFlag);
             } else {
                 ByteBuffer bufferResult = ByteBuffer.allocate(sourceWrap.array().length + plength);
                 bufferResult.put(SydSM4Mac.bytebuffer2ByteArray(sourceWrap));
@@ -88,8 +90,8 @@ public class SydApiSM4 {
                 ByteBuffer bufferResults = ByteBuffer.allocate(remainder);
                 bufferResults.put(bytes1);
                 sourceWrap = bufferResults;
-                api.SYD_SM4_LongData(iKeyIndex, pcdataResult, iPkgNum, iFlag);
                 iPkgNum = 2;
+                return  api.SYD_SM4_LongData(iKeyIndex, pcdataResult, iPkgNum, iFlag);
             }
         }
     }
diff --git a/src/test/java/test/LongDataTest.java b/src/test/java/test/LongDataTest.java
index 2458104..41b9e29 100644
--- a/src/test/java/test/LongDataTest.java
+++ b/src/test/java/test/LongDataTest.java
@@ -6,6 +6,7 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
+import java.util.Arrays;
 import java.util.Random;
 
 public class LongDataTest {
@@ -77,7 +78,7 @@ public class LongDataTest {
             int lucky = new Random().nextInt(4065);
             byte[] data = new byte[lucky];
             System.out.println("len="+lucky);
-            new Random().nextBytes( data );
+//            new Random().nextBytes( data );
             sydApiMac.update(data);
         }
 
@@ -111,6 +112,22 @@ public class LongDataTest {
         System.out.println(Util.bytes2HexString( enData ) );
     }
 
+    @Test
+    public void case12(){
+        for (int i =0 ; i < 1000; i ++) {
+            int lucky = new Random().nextInt(4065);
+            SydApiSM4 sydApiSM4 = api.initSM4(api, 1,1);
+            byte[] bytes = new byte[lucky];
+            sydApiSM4.update(new byte[lucky]);
+            byte[] finish = sydApiSM4.finish();
+            SydApiSM4 sydApiSM42 = api.initSM4(api, 1,0);
+            sydApiSM42.update(finish);
+            byte[] finish1 = sydApiSM42.finish();
+            System.out.println("原始数据："+Arrays.toString(bytes)+",\n"+"解密后数据："+Arrays.toString(finish1));
+
+        }
+
+    }
 
 
 }