“Error occurred during a cryptographic operation”

Question

I've uploaded my website to a webhosting and this error came up;
'Error occurred during a cryptographic operation.'.

I've done some research and it seems that the formauthenticated cookie is bound to the MachineKey (which differs when using webhost).

I've found a method that should fix this problem but the error remains.

CODE:

/// <summary>
    /// This method removes a cookie if the machine key is different than the one that saved the cookie;
    /// </summary>
    protected void Application_Error(object sender, EventArgs e)
    {
        var error = Server.GetLastError();
        var cryptoEx = error as CryptographicException;
        if (cryptoEx != null)
        {
            FederatedAuthentication.WSFederationAuthenticationModule.SignOut();
            Global.Cookies.FormAuthenticated Cookie = new Global.Cookies.FormAuthenticated();
            Cookie.Delete();
            Server.ClearError();
        }
    }

STACKTRACE:

[CryptographicException: Error occurred during a cryptographic operation.]
   System.Web.Security.Cryptography.HomogenizingCryptoServiceWrapper.HomogenizeErrors(Func`2 func, Byte[] input) +115
   System.Web.Security.Cryptography.HomogenizingCryptoServiceWrapper.Unprotect(Byte[] protectedData) +59
   System.Web.Security.FormsAuthentication.Decrypt(String encryptedTicket) +9824926
   Archive_Template.Main.resolveLoginUser(String sessionKey) in f:\Archive_Template\Archive_Template\Main.aspx.cs:481
   Archive_Template.Main.OnPreInit(EventArgs e) in f:\Archive_Template\Archive_Template\Main.aspx.cs:52
   System.Web.UI.Page.PerformPreInit() +31
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +335

Answer 1

I have also experienced this when developing a new solution and running the website on localhost. Setting the machinekey made no difference, but simply deleting all the cookies for localhost solved the problem.

Answer 2

If you are using forms auth. you can signout when you catch the exception and allow your users to login and create a valid cookie

catch (CryptographicException cex)
{
    FormsAuthentication.SignOut();
}

Answer 3

       protected void Application_Error(object sender_, CommandEventArgs e_)
    {
        Exception exception = Server.GetLastError();
        if(exception is CryptographicException)
        {
            FormsAuthentication.SignOut();
        }
    }

in your Global.asax.cs, from Catching errors in Global.asax, as long as you use Forms authentication (login/password). Worked for me.

Answer 4

Another option is to clear the cookies from browser setting and this allows new cookies to get stored.

Answer 5

This is due to the machine key is missing, which is used as a symmetric key to do the encryption and decryption.

To set the machine in the IIS;

Go to your application -> Machine Keys -> Generate Keys

Answer 6

I just had this aswell, i deleted the UserTokenCaches table entries from the database.