获取商户信息，sn解密取值

Areas/Api/Controllers/v1/MainServer/MerchantInfoController.cs

@@ -776,7 +776,7 @@ namespace MySystem.Areas.Api.Controllers.v1
                 }
                 Sn = dbconn.Decrypt3DES(Sn, "l2k0b2#3");
                 Sn = Sn.TrimEnd('\0');
-                Sn = Sn.Substring(0, Sn.Length - 8);
+                Sn = Sn.Substring(0, 20);
             }
             if(Machine == Sn || Machine == "")
             {