diff --git a/src/PaySharp.Unionpay/Merchant.cs b/src/PaySharp.Unionpay/Merchant.cs
index 021ffc3..03ae031 100644
--- a/src/PaySharp.Unionpay/Merchant.cs
+++ b/src/PaySharp.Unionpay/Merchant.cs
@@ -21,11 +21,6 @@ namespace PaySharp.Unionpay
         /// </summary>
         public string CertId { get; internal set; }
 
-        /// <summary>
-        /// 加密证书号
-        /// </summary>
-        public string EncryptCertId { get; internal set; }
-
         /// <summary>
         /// 证书私钥
         /// </summary>
diff --git a/src/PaySharp.Unionpay/PaySharp.Unionpay.csproj b/src/PaySharp.Unionpay/PaySharp.Unionpay.csproj
index da36d6c..0c26122 100644
--- a/src/PaySharp.Unionpay/PaySharp.Unionpay.csproj
+++ b/src/PaySharp.Unionpay/PaySharp.Unionpay.csproj
@@ -28,7 +28,6 @@
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net45'">
     <PackageReference Include="SharpZipLib" Version="0.86.0" />
-    <PackageReference Include="System.ValueTuple" Version="4.3.0" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
diff --git a/src/PaySharp.Unionpay/UnionpayGateway.cs b/src/PaySharp.Unionpay/UnionpayGateway.cs
index 021c681..915342d 100644
--- a/src/PaySharp.Unionpay/UnionpayGateway.cs
+++ b/src/PaySharp.Unionpay/UnionpayGateway.cs
@@ -30,10 +30,9 @@ namespace PaySharp.Unionpay
             : base(merchant)
         {
             _merchant = merchant;
-            //TODO:测试同时读取是否有问题
+
             _merchant.CertId = Util.GetCertId(merchant.CertPath, merchant.CertPwd);
             _merchant.CertKey = Util.GetCertKey(merchant.CertPath, merchant.CertPwd);
-            //_merchant.EncryptCertId = Util.GetEncryptCertId();
         }
 
 #if NETSTANDARD2_0
diff --git a/src/PaySharp.Unionpay/Util.cs b/src/PaySharp.Unionpay/Util.cs
index 233a539..e961422 100644
--- a/src/PaySharp.Unionpay/Util.cs
+++ b/src/PaySharp.Unionpay/Util.cs
@@ -18,6 +18,13 @@ namespace PaySharp.Unionpay
 {
     internal static class Util
     {
+        #region 字段
+
+        private static Pkcs12Store _pkcs12Store;
+        private static string _aliase;
+
+        #endregion
+
         #region 证书
 
         private static X509Certificate ACPENCCER = null;
@@ -34,21 +41,20 @@ namespace PaySharp.Unionpay
         /// <param name="path">证书路径</param>
         /// <param name="pwd">证书密码</param>
         /// <returns></returns>
-        private static (Pkcs12Store Store, string Aliase) GetPkcs12Store(string path, string pwd)
+        private static void GetPkcs12Store(string path, string pwd)
         {
-            using (FileStream fileStream = new FileStream(path, FileMode.Open))
+            using (FileStream fileStream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
             {
-                Pkcs12Store store = new Pkcs12Store(fileStream, pwd.ToCharArray());
-                foreach (string n in store.Aliases)
+                var pkcs12Store = new Pkcs12Store(fileStream, pwd.ToCharArray());
+                foreach (string item in pkcs12Store.Aliases)
                 {
-                    if (store.IsKeyEntry(n))
+                    if (pkcs12Store.IsKeyEntry(item))
                     {
-                        return (store, n);
+                        _pkcs12Store = pkcs12Store;
+                        _aliase = item;
                     }
                 }
             }
-
-            return (null, null);
         }
 
         /// <summary>
@@ -59,9 +65,13 @@ namespace PaySharp.Unionpay
         /// <returns></returns>
         public static string GetCertId(string path, string pwd)
         {
-            var (Store, Aliase) = GetPkcs12Store(path, pwd);
-            return Store
-                .GetCertificateChain(Aliase)[0]
+            if (string.IsNullOrEmpty(_aliase))
+            {
+                GetPkcs12Store(path, pwd);
+            }
+
+            return _pkcs12Store
+                .GetCertificateChain(_aliase)[0]
                 .Certificate
                 .SerialNumber
                 .ToString();
@@ -81,9 +91,13 @@ namespace PaySharp.Unionpay
         /// <returns></returns>
         public static AsymmetricKeyParameter GetCertKey(string path, string pwd)
         {
-            var (Store, Aliase) = GetPkcs12Store(path, pwd);
-            return Store
-                .GetKey(Aliase)
+            if (string.IsNullOrEmpty(_aliase))
+            {
+                GetPkcs12Store(path, pwd);
+            }
+
+            return _pkcs12Store
+                .GetKey(_aliase)
                 .Key;
         }