nsICMSMessage

[lfern]

Hello,

I�m trying to digitaly sign a local file from javascript in a XUL
application. I think nsICMSMessage interface can help me (I�m not sure
it's the only way). I try to create an instance of nsICMSMessage but I
get an exception:
Error: uncaught exception: [Exception... "Component returned failure
code: 0x80570018 (NS_ERROR_XPC_BAD_IID) [nsIJSCID.createInstance]"
nsresult: "0x80570018 (NS_ERROR_XPC_BAD_IID)"  location: "JS frame ::
chrome://testsign/content/testsign.js :: TestSign :: line 57"  data: no]
The line that throw this exception is:

message =
    Components.classes["@mozilla.org/nsCMSMessage;1"].
       createInstance(Components.interfaces.nsICMSMessage);
Can anyone help me?

Thanks!!!