asp.net-mvc – SessionSecurityTokenHandler尝试使用DPAPI解密R

我已经阅读过MSDN论坛,Dominic Baier的博客,以及其他来源,DPAPI将无法在Azure中开箱即用,并且在任何类型的Web场景中处理联合身份验证的一种方法是替换DPAPI转换使用可在整个服务器场中使用的私钥的服务器,例如使用X509证书的RSA加密.我在Azure MVC应用程序中采用了这种方法,并将SessionSecurityTokenHandler配置为：

FederatedAuthentication.ServiceConfigurationCreated += (sender,args) =>
    {
        var sessionTransforms = new List<CookieTransform>(new CookieTransform[]
            {
                new DeflateCookieTransform(),new RsaEncryptionCookieTransform(args.ServiceConfiguration.ServiceCertificate),new RsaSignatureCookieTransform(args.ServiceConfiguration.ServiceCertificate)
            });
        var sessionHandler = new SessionSecurityTokenHandler(sessionTransforms.AsReadOnly());
        args.ServiceConfiguration.SecurityTokenHandlers.AddOrReplace(sessionHandler);                    
    };

使用此配置,我们能够从身份提供商处接收令牌,并发出使用这些转换加密的安全cookie.在Azure模拟器中运行,一切都按预期工作.但是,在Azure环境中,我们间歇性地在浏览器中看到以下错误：

Key not valid for use in specified state.

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.Security.Cryptography.CryptographicException: Key not valid for use in specified state.


Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[CryptographicException: Key not valid for use in specified state.
]
   System.Security.Cryptography.ProtectedData.Unprotect(Byte[] encryptedData,Byte[] optionalEntropy,DataProtectionScope scope) +577
   Microsoft.IdentityModel.Web.ProtectedDataCookieTransform.Decode(Byte[] encoded) +80

[InvalidOperationException: ID1073: A CryptographicException occurred when attempting to decrypt the cookie using the ProtectedData API (see inner exception for details). If you are using IIS 7.5,this could be due to the loadUserProfile setting on the Application Pool being set to false. ]
   Microsoft.IdentityModel.Web.ProtectedDataCookieTransform.Decode(Byte[] encoded) +433
   Microsoft.IdentityModel.Tokens.SessionSecurityTokenHandler.ApplyTransforms(Byte[] cookie,Boolean outbound) +189
   Microsoft.IdentityModel.Tokens.SessionSecurityTokenHandler.ReadToken(XmlReader reader,SecurityTokenResolver tokenResolver) +862
   Microsoft.IdentityModel.Tokens.SessionSecurityTokenHandler.ReadToken(Byte[] token,SecurityTokenResolver tokenResolver) +109
   Microsoft.IdentityModel.Web.SessionAuthenticationModule.ReadSessionTokenFromCookie(Byte[] sessionCookie) +356
   Microsoft.IdentityModel.Web.SessionAuthenticationModule.TryReadSessionTokenFromCookie(SessionSecurityToken& sessionToken) +123
   Microsoft.IdentityModel.Web.SessionAuthenticationModule.OnAuthenticateRequest(Object sender,EventArgs eventArgs) +61
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +80
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step,Boolean& completedSynchronously) +270

这似乎表明SessionSecurityTokenHandler正在尝试使用DPAPI解密cookie,但为什么呢？我没有配置它使用上面的RSA吗？

<system.identityModel>
  <identityConfiguration>
    <securityTokenHandlers>
      <remove type="System.IdentityModel.Tokens.SessionSecurityTokenHandler,System.IdentityModel,Version=4.0.0.0,Culture=neutral,PublicKeyToken=b77a5c561934e089" />
      <add type="System.IdentityModel.Services.Tokens.MachineKeySessionSecurityTokenHandler,System.IdentityModel.Services,PublicKeyToken=b77a5c561934e089" />
    </securityTokenHandlers>
  </identityConfiguration>
</system.identityModel>

<system.web>
  <machineKey validationKey="..." decryptionKey="..." validation="SHA1" decryption="AES" />
</system.web>