Integration Services :: Using Sensitive Project Parameters In Data Flow Tasks

I have a requirement to read an encrypted file as a data source. I am not allowed to save an unencrypted text file version on disc  at any time for any length of time, therefore I created a custom source component that reads an encrypted csv file, decrypts it, and then passes each row of data to the pipeline and ultimately to an ole data destination. Basically it is just a text file reader with an added class that adds functionality that decrypts the file before the component sets columns or reads rows. 

The custom component, “Encrypted File Source”, has a custom property “encryptionkey” with the encryption required flag set to true (code below) and is declared as eligible to be set in the expressions.

IDTSCustomProperty100 EncryptionKey = ComponentMetaData.CustomPropertyCollection.New();
            EncryptionKey.Name =
"EncryptionKey";
            EncryptionKey.Description =
"Secure String key value to decrypt the file";
            EncryptionKey.Value =
string.Empty;
            EncryptionKey.ExpressionType =
DTSCustomPropertyExpressionType.CPET_NOTIFY;
            EncryptionKey.EncryptionRequired =
true;

I want to be able to set the password for the encrypted file in the SQL Agent job that executes the SSIS project. This means I have an environment with a variable, “DataPassword”, that is set to sensitive.  It maps to a Project parameter in the SQL Agent job that is also set to sensitive.  And I now I want to access that sensitive Project Password inside my data flow, specifically in the Encrypted File source task that I created and set my EncryptionKey to that Project Parameter. 

The problem is that SSIS says. 

"expression cannot be evaluated.  ... The Expression will not be evaluated because it contains sensitive parameter value "$Project::DataFilePassord" . Verify that the expression is used properly and that it portects sensitive information"
((Microsoft.DataTransformationsServices.Controls) "<v:shapetype coordsize="21600,21600" filled="f" id="_x0000_t75" o:preferrelative="t" o:spt="75"
path="m@4@5l@4@11@9@11@9@5xe" stroked="f">

[Code] ....

I am using SQL Server 2012, on a windows 7 box with VS2010 premium.