Validation of viewstate MAC failed machinekey生成、使用方法

前段时间公司为了减轻服务器压力，对网页做了集群，分布在多台服务器，通过DNS轮回解析到各台服务器，结果页面只要打开停留到DNS解析到下一个地址，就会出现出下错误信息。

Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException:
Validation of viewstate MAC failed. If this application is hosted by a
Web Farm or cluster, ensure that <machineKey> configuration
specifies the same validationKey and validation algorithm. AutoGenerate
cannot be used in a cluster.

Source Error:

The source code that generated this unhandled exception
can only be shown when compiled in debug mode. To enable this, please
follow one of the below steps, then request the URL:

1. Add a "Debug=true" directive at the top of the file that generated the error. Example:

<%@ Page Language="C#" Debug="true" %>

or:

2) Add the following section to the configuration file of your application:

<configuration>
   <system.web>
       <compilation debug="true"/>
   </system.web>
</configuration>

Note
that this second technique will cause all files within a given
application to be compiled in debug mode. The first technique will cause
only that particular file to be compiled in debug mode.

Important:
Running applications in debug mode does incur a memory/performance
overhead. You should make sure that an application has debugging
disabled before deploying into production scenario.

Stack Trace:

[HttpException (0x80004005): Unable to validate data.]
   System.Web.Configuration.MachineKeySection.GetDecodedData(Byte[] buf, Byte[] modifier, Int32 start, Int32 length, Int32& dataLength) +294
   System.Web.UI.ObjectStateFormatter.Deserialize(String inputString) +203

[ViewStateException: Invalid viewstate.
	Client IP: 218.28.26.86
	Port: 45262
	User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727; FDM)
	ViewState: 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...]

[HttpException (0x80004005): Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.]
   System.Web.UI.ViewStateException.ThrowError(Exception inner, String persistedState, String errorPageMessage, Boolean macValidationError) +267
   System.Web.UI.ObjectStateFormatter.Deserialize(String inputString) +282
   System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter.Deserialize(String serializedState) +4
   System.Web.UI.Util.DeserializeWithAssert(IStateFormatter formatter, String serializedState) +37
   System.Web.UI.HiddenFieldPageStatePersister.Load() +198
   System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +83
   System.Web.UI.Page.LoadAllState() +35
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +7350
   System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +213
   System.Web.UI.Page.ProcessRequest() +86
   System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) +18
   System.Web.UI.Page.ProcessRequest(HttpContext context) +49
   ASP.admin_articleadd_aspx.ProcessRequest(HttpContext context) +4
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +358
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +64

解决方法：

解决方案(1)

处理页面增加

<%@ Page Language="C#"  enableViewStateMac="false" %>

解决方案(2)推荐 
<machineKey

validationKey="B8CEF0C74E23E7197FCC4C9E3617C0007D94D43C7F7A79C582C54B95D69B946DFD49CAF5AA72F9A8CA2CBA040A9DF64DC1DF90DAE1214AE4F1AB7FA56DD65C0D"

decryptionKey="D7F1CE31847C4FB31EF51E14F3820D52B659AF8523FC932C03506CC075DB8B28"
validation="SHA1" decryption="AES" />

转自：http://blog.csdn.net/wrongfu964/article/details/3896991

MachineKey生成方法

打开以下网址：http://www.aspnetresources.com/tools/keycreator.aspx

点击：Generated

生成的Machinekey:

MachineKey

<machineKey
validationKey="86B6275BA31D3D713E41388692FCA68F7D20269411345AA1C17A7386DACC9C46E7CE5F97F556F3CF0A07159659E2706B77731779D2DA4B53BC47BFFD4FD48A54"
decryptionKey="9421E53E196BB56DB11B9C25197A2AD470638EFBC604AC74CD29DBBCF79D6046"
validation="SHA1"
decryption="AES"
/>

MachineKey的使用方法：

将MachineKey添加至Web.config文件的<system.web></system.web>之间

MachineKey的作用：

1. ASP.net 使用 forms authentication 时的 cookie 数据的加密和解密。以确保这部分数据不会被篡改
2. viewstate 数据的加密和解密。以确保这部分数据不会被篡改。
3. 使用进程外session（out-of-process session）时，对会话状态标识进行验证。

更多详细信息请参考：

http://www.wonima.com

http://msdn.microsoft.com/zh-cn/library/ms998288(en-us).aspx