diff --git a/src/main/java/component/CongestionMark.java b/src/main/java/component/CongestionMark.java
index dd41304..1b60af2 100644
--- a/src/main/java/component/CongestionMark.java
+++ b/src/main/java/component/CongestionMark.java
@@ -83,7 +83,12 @@ public class CongestionMark implements TlvComponentBase,InitialAble, IEncodingAb
         }
 
         // 读取 CongestionMark
-        long value=TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        long value= 0;
+        try {
+            value = TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         if(value<0){
             return false;
         }
diff --git a/src/main/java/component/FreshnessPeriod.java b/src/main/java/component/FreshnessPeriod.java
index 0bb27fd..ba33d57 100644
--- a/src/main/java/component/FreshnessPeriod.java
+++ b/src/main/java/component/FreshnessPeriod.java
@@ -83,7 +83,12 @@ public class FreshnessPeriod implements TlvComponentBase,InitialAble, IEncodingA
         }
 
         // 读取 value
-        long value=TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        long value= 0;
+        try {
+            value = TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         if(value<0){
             return false;
         }
diff --git a/src/main/java/component/HopLimit.java b/src/main/java/component/HopLimit.java
index 99be99d..9bb1723 100644
--- a/src/main/java/component/HopLimit.java
+++ b/src/main/java/component/HopLimit.java
@@ -78,7 +78,12 @@ public class HopLimit implements TlvComponentBase,InitialAble, IEncodingAble {
         }
 
         // 读取 HopLimit
-        long value=TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        long value= 0;
+        try {
+            value = TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         if(value<0){
             return false;
         }
diff --git a/src/main/java/component/IdentifierComponent.java b/src/main/java/component/IdentifierComponent.java
index 31fd840..7ce00ff 100644
--- a/src/main/java/component/IdentifierComponent.java
+++ b/src/main/java/component/IdentifierComponent.java
@@ -11,6 +11,7 @@ package component;
 
 import encoding.*;
 import util.ByteHelper;
+import util.ByteHelperException;
 import util.StringHelper;
 
 // @Description:
@@ -58,7 +59,12 @@ public class IdentifierComponent implements TlvComponentBase, IEncodingAble {
         this.identifierBlock=new Block();
         this.identifierBlock.setType(new VlInt(TLV.TlvIdentifierComponent));
         this.identifierBlock.setLength(new VlInt(nameComponent.length()+1));
-        byte[] value=new byte[this.identifierBlock.getLength().getVlIntValue2Int()];
+        byte[] value= new byte[0];
+        try {
+            value = new byte[this.identifierBlock.getLength().getVlIntValue2Int()];
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         value[0]=MarkerString;
         System.arraycopy(nameComponent.getBytes(),0,value,1,nameComponent.getBytes().length);
         this.identifierBlock.setValue(value);
@@ -74,7 +80,12 @@ public class IdentifierComponent implements TlvComponentBase, IEncodingAble {
         this.identifierBlock=new Block();
         this.identifierBlock.setType(new VlInt(TLV.TlvIdentifierComponent));
         this.identifierBlock.setLength(new VlInt(new VlInt(intValue).size()+1));
-        byte[] value=new byte[this.identifierBlock.getLength().getVlIntValue2Int()];
+        byte[] value= new byte[0];
+        try {
+            value = new byte[this.identifierBlock.getLength().getVlIntValue2Int()];
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         value[0]=MarkerNonNegativeInteger;
         System.arraycopy(new VlInt(intValue).getVlIntBytes(),0,value,1,new VlInt(intValue).size());
         this.identifierBlock.setValue(value);
@@ -90,7 +101,12 @@ public class IdentifierComponent implements TlvComponentBase, IEncodingAble {
         this.identifierBlock=new Block();
         this.identifierBlock.setType(new VlInt(TLV.TlvIdentifierComponent));
         this.identifierBlock.setLength(new VlInt(arr.length+1));
-        byte[] value=new byte[this.identifierBlock.getLength().getVlIntValue2Int()];
+        byte[] value= new byte[0];
+        try {
+            value = new byte[this.identifierBlock.getLength().getVlIntValue2Int()];
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         value[0]=MarkerByteArray;
         System.arraycopy(arr,0,value,1,arr.length);
         this.identifierBlock.setValue(value);
@@ -175,7 +191,12 @@ public class IdentifierComponent implements TlvComponentBase, IEncodingAble {
         this.identifierBlock=new Block(block);
 
         //todo:越界问题
-        int length=this.identifierBlock.getLength().getVlIntValue2Int();
+        int length= 0;
+        try {
+            length = this.identifierBlock.getLength().getVlIntValue2Int();
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         byte[] value=this.identifierBlock.getValue();
 
         // 要求TLV-LENGTH至少为1，因为 IdentifierComponent 使用 TLV-VALUE 中的第一个字节作为Marker
@@ -190,7 +211,12 @@ public class IdentifierComponent implements TlvComponentBase, IEncodingAble {
         this.marker=value[0];
 
         // 根据不同类型的Marker，给不同的成员赋值
-        byte[] v=ByteHelper.getTailBytes(value,1);
+        byte[] v= new byte[0];
+        try {
+            v = ByteHelper.getTailBytes(value,1);
+        } catch (ByteHelperException e) {
+            e.printStackTrace();
+        }
         if(isString()){
             this.stringValue=new String(v);
         }else if(isNonNegativeInteger()){
diff --git a/src/main/java/component/InterestLifeTime.java b/src/main/java/component/InterestLifeTime.java
index 606c758..6350de7 100644
--- a/src/main/java/component/InterestLifeTime.java
+++ b/src/main/java/component/InterestLifeTime.java
@@ -83,7 +83,12 @@ public class InterestLifeTime implements TlvComponentBase,InitialAble, IEncoding
         }
 
         // 读取 value
-        long value=TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        long value= 0;
+        try {
+            value = TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         if(value<0){
             return false;
         }
diff --git a/src/main/java/component/NackHeader.java b/src/main/java/component/NackHeader.java
index 6d204e6..b3a3830 100644
--- a/src/main/java/component/NackHeader.java
+++ b/src/main/java/component/NackHeader.java
@@ -83,7 +83,12 @@ public class NackHeader implements TlvComponentBase,InitialAble, IEncodingAble {
         }
 
         // 读取 value
-        long value=TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        long value= 0;
+        try {
+            value = TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         if(value<0){
             return false;
         }
diff --git a/src/main/java/component/Nonce.java b/src/main/java/component/Nonce.java
index b81cac5..e1791ba 100644
--- a/src/main/java/component/Nonce.java
+++ b/src/main/java/component/Nonce.java
@@ -93,7 +93,12 @@ public class Nonce implements TlvComponentBase,InitialAble, IEncodingAble {
         }
 
         // 读取 value
-        long value=TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        long value= 0;
+        try {
+            value = TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         if(value<0){
             return false;
         }
diff --git a/src/main/java/component/SignatureType.java b/src/main/java/component/SignatureType.java
index 7be03d4..befefd3 100644
--- a/src/main/java/component/SignatureType.java
+++ b/src/main/java/component/SignatureType.java
@@ -2,7 +2,6 @@ package component;
 
 import encoding.*;
 import minsecurity.Common;
-import org.omg.CORBA.PRIVATE_MEMBER;
 
 /*
  * @Author: Wang Feng
@@ -44,7 +43,6 @@ class SignatureAlgorithm{
     }
 }
 public class SignatureType implements TlvComponentBase, IEncodingAble {
-//    private SignatureAlgorithm value;
     private SignatureAlgorithm value; // SignatureAlgorithm
 
     /**
diff --git a/src/main/java/component/SignatureValue.java b/src/main/java/component/SignatureValue.java
index 8bddf3e..ca492aa 100644
--- a/src/main/java/component/SignatureValue.java
+++ b/src/main/java/component/SignatureValue.java
@@ -103,7 +103,12 @@ public class SignatureValue implements TlvComponentBase, IEncodingAble {
             return false;
         }
 
-        int len=block.getLength().getVlIntValue2Int();
+        int len= 0;
+        try {
+            len = block.getLength().getVlIntValue2Int();
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         this.value=new byte[len];
         System.arraycopy(block.getValue(),0,this.value,0,len);
         return true;
diff --git a/src/main/java/component/TTL.java b/src/main/java/component/TTL.java
index b5c02b8..c665015 100644
--- a/src/main/java/component/TTL.java
+++ b/src/main/java/component/TTL.java
@@ -94,7 +94,12 @@ public class TTL implements IEncodingAble {
         if(!TLV.expectType(block.getType(),new VlInt(TLV.TlvTTL))){
             return false;
         }
-        long value=TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        long value= 0;
+        try {
+            value = TLV.readNonNegativeInteger(block.getValue(),0,block.getLength().getVlIntValue2Int());
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         if(value<0){
             return false;
         }
diff --git a/src/main/java/encoding/Block.java b/src/main/java/encoding/Block.java
index f9816f4..711fa98 100644
--- a/src/main/java/encoding/Block.java
+++ b/src/main/java/encoding/Block.java
@@ -1,6 +1,7 @@
 package encoding;
 
 import util.ByteHelper;
+import util.ByteHelperException;
 
 import java.util.LinkedList;
 import java.util.List;
@@ -43,7 +44,12 @@ public class Block {
         }
 
         // 读取length
-        VlInt tlvLength=TLV.readVarNumber(buffer,new VlInt(tlvType.size()));
+        VlInt tlvLength= null;
+        try {
+            tlvLength = TLV.readVarNumber(buffer,new VlInt(tlvType.size()));
+        } catch (ByteHelperException e) {
+            e.printStackTrace();
+        }
         if(tlvLength==null){
             return null;
         }
@@ -197,7 +203,7 @@ public class Block {
      * 	2. 如果TLV的value不为空，且不存在嵌套的子TLV，则会抛出错误
      * @return
      */
-    public boolean parseSubElements(){
+    public boolean parseSubElements() {
         if((this.value.length==0)||this.elements.length()!=0){
             return true;
         }
@@ -213,7 +219,12 @@ public class Block {
             start+=tlvType.size();
 
             // 读取 TLV-LENGTH
-            VlInt tlvLength=TLV.readVarNumber(this.value,new VlInt(start));
+            VlInt tlvLength= null;
+            try {
+                tlvLength = TLV.readVarNumber(this.value,new VlInt(start));
+            } catch (ByteHelperException e) {
+                e.printStackTrace();
+            }
             if(tlvType==null){
                 this.clearElements();
                 return false;
@@ -227,14 +238,19 @@ public class Block {
             }
 
             // 创建一个子 TLV Block 并添加到elements当中
-            byte[] subBlockValue=new byte[tlvLength.getVlIntValue2Int()];
-            System.arraycopy(this.value,start,subBlockValue,0,tlvLength.getVlIntValue2Int());
-            Block block=createBlockByTypeLengthBuffer(tlvType,tlvLength,subBlockValue,true);
-            if(block==null){
-                return false;
+            byte[] subBlockValue= new byte[0];
+            try {
+                subBlockValue = new byte[tlvLength.getVlIntValue2Int()];
+                System.arraycopy(this.value,start,subBlockValue,0,tlvLength.getVlIntValue2Int());
+                Block block=createBlockByTypeLengthBuffer(tlvType,tlvLength,subBlockValue,true);
+                if(block==null){
+                    return false;
+                }
+                this.addElement(block);
+                start+=tlvLength.getVlIntValue2Int();
+            } catch (VlIntException e) {
+                e.printStackTrace();
             }
-            this.addElement(block);
-            start+=tlvLength.getVlIntValue2Int();
         }
         return true;
     }
diff --git a/src/main/java/encoding/TLV.java b/src/main/java/encoding/TLV.java
index 4a55963..8efb38c 100644
--- a/src/main/java/encoding/TLV.java
+++ b/src/main/java/encoding/TLV.java
@@ -2,6 +2,7 @@ package encoding;
 
 
 import util.ByteHelper;
+import util.ByteHelperException;
 
 /*
  * @Author: Wang Feng
@@ -72,13 +73,15 @@ public class TLV {
      * @param start
      * @return
      */
-    public static VlInt readVarNumber(byte[] buffer,VlInt start){
+    public static VlInt readVarNumber(byte[] buffer,VlInt start) throws ByteHelperException {
         VlInt length=new VlInt(buffer.length);
         if(start.compareTo(length)>=0){
             return null;
         }
 
-        int firstbyte=ByteHelper.uint8ToInt(ByteHelper.getFirstByte(buffer,start));
+        int firstbyte= 0;
+        firstbyte = ByteHelper.uint8ToInt(ByteHelper.getFirstByte(buffer,start));
+
         if(firstbyte<241){
             return new VlInt(firstbyte);
         }else if(firstbyte==241){
@@ -108,7 +111,12 @@ public class TLV {
      * @return
      */
     public static VlInt readType(byte[] buffer,VlInt start){
-        VlInt tlvType=readVarNumber(buffer,start);
+        VlInt tlvType= null;
+        try {
+            tlvType = readVarNumber(buffer,start);
+        } catch (ByteHelperException e) {
+            e.printStackTrace();
+        }
 
         if(tlvType==null||tlvType.isEqual(0)||tlvType.compareTo(MaxTlvNum)>0){
             return null;
diff --git a/src/main/java/encoding/VlInt.java b/src/main/java/encoding/VlInt.java
index 3df4866..d44534a 100644
--- a/src/main/java/encoding/VlInt.java
+++ b/src/main/java/encoding/VlInt.java
@@ -4,6 +4,7 @@ package encoding;
 import util.ByteHelper;
 
 import java.math.BigInteger;
+import java.util.Arrays;
 
 import static java.lang.Math.pow;
 
@@ -117,22 +118,23 @@ public class VlInt {
      * 将vlint转为一个int输出：需要判断size是不是小于4(1 or 3)
      * @return
      */
-    public int getVlIntValue2Int(){
+    public int getVlIntValue2Int() throws VlIntException {
         if(this.size()<4){
             return VlIntValue.intValue();
         }
-        return Integer.parseInt(null);
+        throw new VlIntException("value大于int能表示的范围");
     }
 
     /**
      * 将vlint转为一个long输出：需要判断size是不是小于8(5)
+     *
      * @return
      */
-    public long getVlIntValue2Long(){
-        if(this.size()<8){
+    public long getVlIntValue2Long() throws VlIntException {
+        if(this.size()<= 9){
             return VlIntValue.longValue();
         }
-        return Long.parseLong(null);
+        throw new VlIntException("value大于long能表示的范围");
     }
 
     /**
@@ -190,8 +192,8 @@ public class VlInt {
      * @param vlInt
      * @return
      */
-    public int subtract(VlInt vlInt){
-        return this.VlIntValue.subtract(vlInt.VlIntValue).intValue();
+    public long subtract(VlInt vlInt){
+        return this.VlIntValue.subtract(vlInt.VlIntValue).longValue();
     }
 
     /**
@@ -199,11 +201,11 @@ public class VlInt {
      * @param vlInt
      * @return
      */
-    public int add(VlInt vlInt){
-        return this.VlIntValue.add(vlInt.VlIntValue).intValue();
+    public long add(VlInt vlInt){
+        return this.VlIntValue.add(vlInt.VlIntValue).longValue();
     }
-    public int add(int i_int){
-        return this.VlIntValue.intValue()+i_int;
+    public long add(int i_int){
+        return this.VlIntValue.longValue()+i_int;
     }
 
     /**
@@ -263,6 +265,16 @@ public class VlInt {
         return vlintValue;
     }
 
+
+    @Override
+    public String toString() {
+        return "VlInt{" +
+                "VlIntBytes=" + Arrays.toString(VlIntBytes) +
+                ", VlIntValue=" + VlIntValue +
+                ", size=" + size +
+                '}';
+    }
+
     // 测试
     public static void main(String[] args){
 //        BigInteger bigInteger=new BigInteger("3");
diff --git a/src/main/java/encoding/VlIntException.java b/src/main/java/encoding/VlIntException.java
new file mode 100644
index 0000000..91b6319
--- /dev/null
+++ b/src/main/java/encoding/VlIntException.java
@@ -0,0 +1,14 @@
+package encoding;
+
+/*
+ * @Author: hongyu guo
+ * @Description:
+ * @Version: 1.0.0
+ * @Date: 19:38 2021/03/15
+ * @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
+ */
+public class VlIntException extends Exception{
+    public VlIntException(String msg){
+        super(msg);
+    }
+}
diff --git a/src/main/java/minsecurity/certificate/cert/Certificate.java b/src/main/java/minsecurity/certificate/cert/Certificate.java
index 8c50bd4..f2942b6 100644
--- a/src/main/java/minsecurity/certificate/cert/Certificate.java
+++ b/src/main/java/minsecurity/certificate/cert/Certificate.java
@@ -165,7 +165,7 @@ public class Certificate {
                 "version=" + version +
                 ", serialNumber=" + serialNumber +
                 ", publicKey=" + publicKey +
-                ", signature=" + ByteUtils.toHexString(signature) +
+                ", signature=" + (signature != null ? ByteUtils.toHexString(signature) : "null") +
                 ", signatureAlgorithm=" + signatureAlgorithm +
                 ", publicKeyAlgorithm=" + publicKeyAlgorithm +
                 ", issueTo='" + issueTo + '\'' +
diff --git a/src/main/java/minsecurity/certificate/cert/InnerCertificate.java b/src/main/java/minsecurity/certificate/cert/InnerCertificate.java
index d36caa4..88cac63 100644
--- a/src/main/java/minsecurity/certificate/cert/InnerCertificate.java
+++ b/src/main/java/minsecurity/certificate/cert/InnerCertificate.java
@@ -46,7 +46,7 @@ public class InnerCertificate {
         return "InnerCertificate{" +
                 "tbsCertificate=" + tbsCertificate.toString() +
                 ", signatureAlgorithm=" + signatureAlgorithm +
-                ", signatureValue=" + ByteUtils.toHexString(signatureValue) +
+                ", signatureValue=" + (signatureValue != null ? ByteUtils.toHexString(signatureValue) : "null") +
                 '}';
     }
 }
diff --git a/src/main/java/minsecurity/certificate/cert/TbsCertificate.java b/src/main/java/minsecurity/certificate/cert/TbsCertificate.java
index f024096..6acef5d 100644
--- a/src/main/java/minsecurity/certificate/cert/TbsCertificate.java
+++ b/src/main/java/minsecurity/certificate/cert/TbsCertificate.java
@@ -152,7 +152,7 @@ public class TbsCertificate {
         return "TbsCertificate{" +
                 "version=" + version +
                 ", serialNumber=" + serialNumber +
-                ", publicKey=" + ByteUtils.toHexString(publicKey) +
+                ", publicKey=" + (publicKey != null ?ByteUtils.toHexString(publicKey) : "null") +
                 ", signatureAlgorithm=" + signatureAlgorithm +
                 ", publicKeyAlgorithm=" + publicKeyAlgorithm +
                 ", issueTo='" + issueTo + '\'' +
diff --git a/src/main/java/minsecurity/crypto/KeyUtils.java b/src/main/java/minsecurity/crypto/KeyUtils.java
index 71ae11a..0e4f6f2 100644
--- a/src/main/java/minsecurity/crypto/KeyUtils.java
+++ b/src/main/java/minsecurity/crypto/KeyUtils.java
@@ -13,6 +13,7 @@ import minsecurity.crypto.sm2.SM2PublicKey;
  */
 public class KeyUtils {
     /**
+     * 可以理解为公钥的"构造函数"
      * 返回的数据类型为PublicKeyInterface接口, 必要时调用者需要手动将类型强制转化为需要的类型
      * @param bytesOfPublicKey 公钥的bytes数组
 	 * @param algorithm 公钥类型
@@ -33,7 +34,16 @@ public class KeyUtils {
                 return null;
         }
     }
-
+    /**
+     * 可以理解为私钥的"构造函数"
+     * 返回的数据类型为PrivateKeyInterface接口, 必要时调用者需要手动将类型强制转化为需要的类型
+     * @param bytesOfPrivateKey 私钥的bytes数组
+	 * @param algorithm 私钥类型
+     * @return minsecurity.crypto.PrivateKeyInterface
+     * @throws
+     * @author hongyu guo
+     * @date 2021/3/15
+    **/
     public static PrivateKeyInterface unMarshalPrivateKey(byte[] bytesOfPrivateKey, int algorithm){
         if(bytesOfPrivateKey == null || bytesOfPrivateKey.length == 0){
             return null;
@@ -48,6 +58,14 @@ public class KeyUtils {
         }
     }
 
+    /**
+     * 获取一个16字节的byte数组, 可用作sm4的key
+     * @param passwd 密码
+     * @return byte[]
+     * @throws
+     * @author hongyu guo
+     * @date 2021/3/15
+    **/
     public static byte[] get16bytePasswd(byte[] passwd) {
         byte[] hashPasswd = HashAlgo.sm3(passwd);
         if( hashPasswd.length == 32){
diff --git a/src/main/java/minsecurity/crypto/SM4.java b/src/main/java/minsecurity/crypto/SM4.java
index 6830489..29a1b3a 100644
--- a/src/main/java/minsecurity/crypto/SM4.java
+++ b/src/main/java/minsecurity/crypto/SM4.java
@@ -29,6 +29,14 @@ public class SM4 {
      */
     public static final int DEFAULT_KEY_SIZE = 128;
 
+    /**
+     * 生成16字节的sm4 key
+     * @param
+     * @return byte[]
+     * @throws NoSuchAlgorithmException
+     * @author hongyu guo
+     * @date 2021/3/15
+    **/
     public static byte[] generateKey() throws NoSuchAlgorithmException, NoSuchProviderException {
         return generateKey(DEFAULT_KEY_SIZE);
     }
diff --git a/src/main/java/minsecurity/crypto/sm2/SM2Base.java b/src/main/java/minsecurity/crypto/sm2/SM2Base.java
index afe9531..b84049b 100644
--- a/src/main/java/minsecurity/crypto/sm2/SM2Base.java
+++ b/src/main/java/minsecurity/crypto/sm2/SM2Base.java
@@ -165,7 +165,14 @@ public class SM2Base {
                 parameterSpec.getN(), parameterSpec.getH());
         return new ECPublicKeyParameters(ecPubKey.getQ(), domainParameters);
     }
-
+    /**
+     * 生成一对sm2公私钥
+     * @param
+     * @return minsecurity.crypto.sm2.SM2KeyPair
+     * @throws
+     * @author hongyu guo
+     * @date 2021/3/15
+    **/
     public static SM2KeyPair generateSM2KeyPair(){
         return SM2KeyPair.generateKeyPair();
     }
diff --git a/src/main/java/minsecurity/identity/Identity.java b/src/main/java/minsecurity/identity/Identity.java
index 262cbf5..b3c39c5 100644
--- a/src/main/java/minsecurity/identity/Identity.java
+++ b/src/main/java/minsecurity/identity/Identity.java
@@ -336,8 +336,8 @@ public class Identity {
                 "Name='" + Name + '\'' +
                 ", KeyParam.signAlgo=" + KeyParam.SignatureAlgorithm +
                 ", KeyParam.pubAlgo=" + KeyParam.PublicKeyAlgorithm +
-                ", Prikey=" + ByteUtils.toHexString(Prikey.getBytes()) +
-                ", pubKey=" + ByteUtils.toHexString(Pubkey.getBytes()) +
+                ", Prikey=" + (Prikey != null ? ByteUtils.toHexString(Prikey.getBytes()) : "null") +
+                ", pubKey=" + (Pubkey != null ? ByteUtils.toHexString(Pubkey.getBytes()) : "null") +
                 ", PrikeyRawByte=" + (PrikeyRawByte == null ? "null":ByteUtils.toHexString(PrikeyRawByte)) +
                 ", Pubkey=" + Pubkey +
                 ", Passwd='" + Passwd + '\'' +
diff --git a/src/main/java/minsecurity/identity/InnerIdentity.java b/src/main/java/minsecurity/identity/InnerIdentity.java
index c74226e..a59dd38 100644
--- a/src/main/java/minsecurity/identity/InnerIdentity.java
+++ b/src/main/java/minsecurity/identity/InnerIdentity.java
@@ -81,7 +81,8 @@ public class InnerIdentity {
     public String toString() {
         return "InnerIdentity{" +
                 "Name='" + Name + '\'' +
-                ", KeyParam=" + KeyParam +
+                ", KeyParam.PublicKeyAlgorithm=" + KeyParam.PublicKeyAlgorithm +
+                ", KeyParam.SignatureAlgorithm=" + KeyParam.SignatureAlgorithm +
                 ", Prikey=" + (Prikey == null ? "null" : ByteUtils.toHexString(Prikey)) +
                 ", Pubkey=" + (Pubkey == null ? "null" : ByteUtils.toHexString(Pubkey)) +
                 ", Passwd='" + Passwd + '\'' +
diff --git a/src/main/java/util/ByteHelper.java b/src/main/java/util/ByteHelper.java
index 22eb1eb..9590a52 100644
--- a/src/main/java/util/ByteHelper.java
+++ b/src/main/java/util/ByteHelper.java
@@ -2,6 +2,10 @@ package util;
 
 
 import encoding.VlInt;
+import encoding.VlIntException;
+
+import java.lang.reflect.Array;
+import java.util.Arrays;
 
 /*
  * @Author: Wang Feng
@@ -18,7 +22,9 @@ public class ByteHelper {
      * @param startIndex
      * @return
      */
-    public static byte[] getTailBytes(byte[] buffer,int startIndex){
+    public static byte[] getTailBytes(byte[] buffer,int startIndex) throws ByteHelperException {
+        if(startIndex >= buffer.length || startIndex < 0)
+            throw new ByteHelperException("buffer out of bounds");
         int len=buffer.length-startIndex;
         byte[] newBytes=new byte[len];
         System.arraycopy(buffer,startIndex,newBytes,0,len);
@@ -27,16 +33,25 @@ public class ByteHelper {
 
     /**
      * 从byte[]数组指定开始位置获取第一个字节
-     * todo: start位置可能是大于int类型的数值
+     *
      * @param buffer
      * @param start
      * @return
      */
-    public static byte getFirstByte(byte[] buffer, VlInt start){
-        int startInt=start.getVlIntValue2Int();
-        byte[] firstbyte=new byte[1];
-        System.arraycopy(buffer,startInt,firstbyte,0,firstbyte.length);
-        return firstbyte[0];
+    public static byte getFirstByte(byte[] buffer, VlInt start) throws ByteHelperException {
+        int startInt= 0;
+        try {
+            startInt = start.getVlIntValue2Int();
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
+        if(startInt >= buffer.length || startInt < 0){
+            throw new ByteHelperException("buffer out of bounds");
+        }
+        return buffer[startInt];
+        // byte[] firstbyte=new byte[1];
+        // System.arraycopy(buffer,startInt,firstbyte,0,firstbyte.length);
+        // return firstbyte[0];
     }
 
     /**
@@ -46,16 +61,33 @@ public class ByteHelper {
      * @param start
      * @return
      */
-    public static byte[] getLenBytes(byte[] buffer, VlInt start,VlInt len){
-        int startInt=start.getVlIntValue2Int();
-        int lenInt=len.getVlIntValue2Int();
+    public static byte[] getLenBytes(byte[] buffer, VlInt start,VlInt len) throws ByteHelperException {
+        int startInt= -1;
+        int lenInt = -1;
+        try {
+            startInt = start.getVlIntValue2Int();
+            lenInt=len.getVlIntValue2Int();
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
+        if(startInt >= buffer.length || startInt < 0){
+            throw new ByteHelperException("buffer out of bounds");
+        }
+        if(lenInt < 0){
+            throw new ByteHelperException("len should > 0");
+        }
         byte[] lenbytes=new byte[lenInt];
 //        byte[] lenbytes=new byte[1];
         System.arraycopy(buffer,startInt,lenbytes,0,lenInt);
         return lenbytes;
     }
     public static byte[] getLenBytes(byte[] buffer, VlInt start,int len){
-        int startInt=start.getVlIntValue2Int();
+        int startInt= -1;
+        try {
+            startInt = start.getVlIntValue2Int();
+        } catch (VlIntException e) {
+            e.printStackTrace();
+        }
         byte[] lenbytes=new byte[len];
 //        byte[] lenbytes=new byte[1];
         System.arraycopy(buffer,startInt,lenbytes,0,len);
@@ -118,11 +150,11 @@ public class ByteHelper {
         if(bytes.length!=8){
             return Integer.parseInt(null);
         }
-        int value= 0;
+        long value= 0;
         //由高位到低位
         for (int i = 0; i < 8; i++) {
             int offset= (bytes.length - 1 - i) * 8;
-            value +=(bytes[i] & 0x000000000000ff) << offset; //往高位游
+            value +=((long)bytes[i] & 0xff) << offset; //往高位游
         }
         return value;
     }
@@ -217,6 +249,7 @@ public class ByteHelper {
             bytes[i] = 0x00;
         }
         System.arraycopy(uint32,0,bytes,4,uint32.length);
+        // System.out.println(Arrays.toString(uint32) + "uint32ToLong: " + Arrays.toString(bytes));
         return byteArrayToLong(bytes);
     }
 
diff --git a/src/main/java/util/ByteHelperException.java b/src/main/java/util/ByteHelperException.java
new file mode 100644
index 0000000..995993a
--- /dev/null
+++ b/src/main/java/util/ByteHelperException.java
@@ -0,0 +1,14 @@
+package util;
+
+/*
+ * @Author: hongyu guo
+ * @Description:
+ * @Version: 1.0.0
+ * @Date: 17:38 2021/03/15
+ * @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
+ */
+public class ByteHelperException extends Exception{
+    public ByteHelperException(String msg){
+        super(msg);
+    }
+}
diff --git a/src/test/java/encoding/BlockTest.java b/src/test/java/encoding/BlockTest.java
index b132d18..f7648bd 100644
--- a/src/test/java/encoding/BlockTest.java
+++ b/src/test/java/encoding/BlockTest.java
@@ -16,7 +16,7 @@ import static org.junit.Assert.*;
 public class BlockTest {
 
     @Test
-    public void TestCreateBlockByTypeLengthBuffer() {
+    public void TestCreateBlockByTypeLengthBuffer() throws VlIntException {
         byte[] buf = new byte[10000];
         Block block = Block.createBlockByTypeLengthBuffer(new VlInt(241), new VlInt(8000),ByteHelper.getLenBytes(buf, new VlInt(0),8000),true);
         //测试type与size
@@ -42,7 +42,7 @@ public class BlockTest {
 
     //error:block.Size().size()错误。
     @Test
-    public void TestCreateBlockByBuffer() {
+    public void TestCreateBlockByBuffer() throws VlIntException {
         byte[] buf = new byte[10000];
         buf[0] = (byte)212;
         buf[1] = (byte)241;
@@ -59,7 +59,7 @@ public class BlockTest {
     }
 
     @Test
-    public void TestBuildByBlock(){
+    public void TestBuildByBlock() throws VlIntException {
         //Block构造方法测试
         byte[] buf = new byte[10000];
         Block block1 = Block.createBlockByTypeLengthBuffer(new VlInt(241), new VlInt(8000),ByteHelper.getLenBytes(buf, new VlInt(0),8000),true);
@@ -85,7 +85,7 @@ public class BlockTest {
     }
 
     @Test
-    public void TestBuildByTypeLengthBuffer(){
+    public void TestBuildByTypeLengthBuffer() throws VlIntException {
         //Block构造方法测试
         byte[] buf = new byte[10000];
         Block block = new Block(new VlInt(241),new VlInt(8000),ByteHelper.getLenBytes(buf,new VlInt(0),8000),true);
diff --git a/src/test/java/encoding/VlIntTest.java b/src/test/java/encoding/VlIntTest.java
index b60f337..036133a 100644
--- a/src/test/java/encoding/VlIntTest.java
+++ b/src/test/java/encoding/VlIntTest.java
@@ -1,8 +1,10 @@
 package encoding;
 
 
+import minsecurity.crypto.TestSM2;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.slf4j.LoggerFactory;
 
 import java.math.BigInteger;
 
@@ -17,6 +19,8 @@ import static org.junit.Assert.*;
  */
 
 public class VlIntTest {
+    private static final org.slf4j.Logger logger = LoggerFactory.getLogger(VlIntTest.class);
+
 
 //    @Test
 //    public void size() {
@@ -41,7 +45,7 @@ public class VlIntTest {
     }
 
     @Test
-    public void getVlIntValue2Int() {
+    public void getVlIntValue2Int() throws VlIntException {
         //vlint(int)的size小于4时，测试是否能准确转为int输出
         int a = 222;
         int a2 = 22222222;
@@ -66,18 +70,25 @@ public class VlIntTest {
 
     //error：以bytes[]形式构造的VlInt，2^31-1 到 2^32-1之间的数会出错
     @Test
-    public void getVlIntValue2Long() {
+    public void getVlIntValue2Long() throws VlIntException {
         long l1 = new Long(0);
         long l2 = new Long(1);
         long l3 = new Long(4294967295L);  //2^32-1
         byte[] b1 = new byte[]{0x00,0x7f,(byte) 0xff,(byte) 0xff,(byte) 0xff};//2^31-1
-        byte[] b2= new byte[]{0x00,(byte) 0x80,0x00,0x00,0x00};//2^31
-
+        byte[] b2 = new byte[]{0x00,(byte) 0x80,0x00,0x00,0x00};//2^31
+        byte[] b3 = new byte[]{0,0,0,0,-128,0,0,0};
+        BigInteger bigInteger = new BigInteger(b2);
+        System.out.println(bigInteger.longValue());
+        System.out.println(new BigInteger(b3).longValue());
         VlInt vlInt_long1 = new VlInt(l1);      // size = 1
         VlInt vlInt_long2 = new VlInt(l2);      // size = 1
         VlInt vlInt_long3 = new VlInt(l3);      // size = 5
         VlInt vlInt_long4 = new VlInt(b1);
         VlInt vlInt_long5 = new VlInt(b2);
+        System.out.println(vlInt_long2.toString());
+        System.out.println(vlInt_long3.toString());
+        System.out.println(vlInt_long4.toString());
+        System.out.println(vlInt_long5.toString());
         //以VlInt(long)形式构造的VlInt
         assertEquals(vlInt_long1.getVlIntValue2Long(),l1);
         assertEquals(vlInt_long2.getVlIntValue2Long(),l2);
@@ -85,6 +96,12 @@ public class VlIntTest {
         ///以VlInt(bytes[])形式构造的VlInt
         assertEquals(vlInt_long4.getVlIntValue2Long(),2147483647L);//2^31-1
         assertEquals(vlInt_long5.getVlIntValue2Long(),2147483648L);//2^31
+
+
+        assertEquals(vlInt_long5.getVlIntValue2Long(),2147483648L);//2^31
+        byte[] bytes1 = new byte[]{127,-128,-128,-128,-128,-128,-128,-128};
+        VlInt vlInt_6 = new VlInt(new BigInteger("21474836481"));
+        assertEquals(vlInt_6.getVlIntValue2Long(), new BigInteger("21474836481").longValue());
     }
 
     //error：以bytes[]形式构造的VlInt，在大于2^31-1的数会出错
@@ -157,21 +174,25 @@ public class VlIntTest {
         int a1 = 0,a2 = 65535;
         long l = 4294967296L;
         int s1 = a2-a1,s2 = a1-a2;
-//        long r1 = l-a1,r2 = l-a2; //差值越界int最大值
+        long r1 = l-a1,r2 = l - (long)a2; //差值越界int最大值
         VlInt vlInt1 = new VlInt(a1);
         VlInt vlInt2 = new VlInt(a2);
         VlInt vlInt3 = new VlInt(l);
+        logger.debug(vlInt1.toString());
+        logger.debug(vlInt2.toString());
+        logger.debug(vlInt3.toString());
+
         assertEquals(vlInt2.subtract(vlInt1),s1);
         assertEquals(vlInt1.subtract(vlInt2),s2); //差为负数
         //error:差值越界int最大值
-//        assertEquals(vlInt3.subtract(vlInt2),r1);
+        assertEquals(vlInt3.subtract(vlInt2), r2);
 
 
         int sum1 = a1+a2;
         long sum2 = a2+l;
         //param：VlInt
         assertEquals(vlInt1.add(vlInt2),sum1);
-//        assertEquals(vlInt1.add(vlInt3),sum2);  //两者之和为long，越界int最大值
+        assertEquals(vlInt2.add(vlInt3),sum2);  //两者之和为long，越界int最大值
         //param：int
         assertEquals(vlInt1.add(a2),sum1);
     }
diff --git a/src/test/java/minsecurity/certificate/cert/TestCert.java b/src/test/java/minsecurity/certificate/cert/TestCert.java
index 70f8249..92af7fc 100644
--- a/src/test/java/minsecurity/certificate/cert/TestCert.java
+++ b/src/test/java/minsecurity/certificate/cert/TestCert.java
@@ -26,7 +26,6 @@ public class TestCert {
         ECPrivateKeyParameters priKey = (ECPrivateKeyParameters) keyPair.getPrivate();
         ECPublicKeyParameters pubKey = (ECPublicKeyParameters) keyPair.getPublic();
         byte[] d = priKey.getD().toByteArray();
-        // d = Arrays.copyOf(d,32);
         byte[] x = pubKey.getQ().getAffineXCoord().getEncoded();
         byte[] y = pubKey.getQ().getAffineYCoord().getEncoded();
         SM2PrivateKey sm2PrivateKey = new SM2PrivateKey(d);
@@ -94,7 +93,7 @@ public class TestCert {
 
         String pem2 = CertUtils.toPem(certificate, new byte[]{1,2,3,4,5,6,7,8},Common.SM4ECB);
         Certificate certFromPem2 = CertUtils.fromPem(pem2, new byte[]{1,2,3,4,5,6,7,8},Common.SM4ECB);
-        logger.debug(certFromPem.toString());
+        logger.debug(certFromPem2.toString());
         assertTrue(CertUtils.verifyCert(certFromPem2,certFromPem2));
     }
 
diff --git a/src/test/java/testPrivate.java b/src/test/java/testPrivate.java
new file mode 100644
index 0000000..2b09a1a
--- /dev/null
+++ b/src/test/java/testPrivate.java
@@ -0,0 +1,20 @@
+import minsecurity.crypto.sm2.SM2KeyPair;
+import org.bouncycastle.pqc.math.linearalgebra.ByteUtils;
+
+/*
+ * @Author: hongyu guo
+ * @Description:
+ * @Version: 1.0.0
+ * @Date: 17:22 2021/03/15
+ * @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
+ */
+public class testPrivate {
+    private void func1(){
+        System.out.println("private func1");
+    }
+
+    private void func2(int a, SM2KeyPair sm2KeyPair){
+        System.out.println("a = " + a);
+        System.out.println("private key = " + ByteUtils.toHexString(sm2KeyPair.getSm2PrivateKey().getBytes()));
+    }
+}
diff --git a/src/test/java/util/ByteHelperTest.java b/src/test/java/util/ByteHelperTest.java
index 0b8c1d5..ae4c529 100644
--- a/src/test/java/util/ByteHelperTest.java
+++ b/src/test/java/util/ByteHelperTest.java
@@ -14,8 +14,7 @@ import static org.junit.Assert.*;
  */public class ByteHelperTest {
 
     @Test
-    public void getTailBytes(){
-        ByteHelper byteHelper = new ByteHelper();
+    public void getTailBytes() throws ByteHelperException {
         //偶数字节
         byte[] buffer = new byte[]{0x00,0x01,(byte) 0x80,0x7f};          //1
         byte[] test1 = new byte[]{0x01,(byte) 0x80,0x7f};
@@ -23,16 +22,15 @@ import static org.junit.Assert.*;
         byte[] buffer2 = new byte[]{0x00,0x00,0x00,0x00,0x00,0x00,0x00,(byte) 0xff, (byte) 0xff}; //65535
         byte[] test2 = new byte[]{0x00,0x00,0x00,0x00,0x00,0x00,(byte) 0xff, (byte) 0xff}; //65535
         int startIndex = 1;
-        byte[] b = byteHelper.getTailBytes(buffer,startIndex);
-        byte[] b2 = byteHelper.getTailBytes(buffer2,startIndex);
+        byte[] b = ByteHelper.getTailBytes(buffer,startIndex);
+        byte[] b2 = ByteHelper.getTailBytes(buffer2,startIndex);
         assertArrayEquals(b,test1);
         assertArrayEquals(b2,test2);
     }
 
-    //todo:对start值进行限定，应当小于Byte数组的length
     @Test
-    public void getFirstByte() {
-        byte[] b0 = new byte[]{0x00,0x00,0x01};
+    public void getFirstByte() throws ByteHelperException {
+        byte[] b0 = new byte[]{0x00,0x00,1};
         byte[] test = new byte[]{0x7f,0x7f,0x7f,0x7f};
         VlInt start0 = new VlInt(b0);
         byte firstbyte = ByteHelper.getFirstByte(test,start0);
@@ -41,7 +39,7 @@ import static org.junit.Assert.*;
 
 
     @Test
-    public void getLenBytes() {
+    public void getLenBytes() throws ByteHelperException {
         byte[] buffer = new byte[]{0x00,0x00,0x01, (byte) 0xff};  //255
         byte[] test = new byte[]{0x00,0x00,0x01};
         VlInt start = new VlInt(0);