"Padding is invalid and cannot be removed." error with a twist...

Question

I'm getting the following error in our QA environment but only through the IIS7 reverse proxy. If I hit the application server directly it works fine. In our DEV environment it works fine through the proxy or directly.

I'm not really sure where to go with this, any ideas?

Server Error in '/' Application.
Padding is invalid and cannot be removed.
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: Padding is invalid and cannot be removed.

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: Padding is invalid and cannot be removed.]
   System.Security.Cryptography.RijndaelManagedTransform.DecryptData(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount, Byte[]& outputBuffer, Int32 outputOffset, PaddingMode paddingMode, Boolean fLast) +2910
   System.Security.Cryptography.RijndaelManagedTransform.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount) +286
   System.Security.Cryptography.CryptoStream.FlushFinalBlock() +51
   System.Web.Configuration.MachineKeySection.EncryptOrDecryptData(Boolean fEncrypt, Byte[] buf, Byte[] modifier, Int32 start, Int32 length, IVType ivType, Boolean useValidationSymAlgo) +318
   System.Web.UI.Page.DecryptStringWithIV(String s, IVType ivType) +115
   System.Web.Handlers.AssemblyResourceLoader.System.Web.IHttpHandler.ProcessRequest(HttpContext context) +140
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +599
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +171


Version Information: Microsoft .NET Framework Version:2.0.50727.4952; ASP.NET Version:2.0.50727.4927 

Answer 1

If this is happens on page with out post back then probably your proxy is convertting the url in lowercase chars and break the code.

I have one more bigger answer here with a trick to log the error and see whats really get on your page:

http://stackoverflow.com/questions/1821243/cryptographicexception-padding-is-invalid-and-cannot-be-removed-and-validation-o/2551810#2551810