http://zqktlw5bf6oycxq6qod452xnvdfcqhfwliz54bkul736g6b454jrk2ad.onion/wiki/index.php?title=Intrusive_Surveillance&action=edit
However, if the key/data is a substantial portion of the prosecution's case, and the sentence you are facing is more than 6 months (or if you are a hardcore civil libertarian type), you may want to tell them to fuck off anyway. Probably would get you a good deal of (most likely positive) press attention. Nobody likes to see people imprisoned for refusing to testify against themselves, even if some legal loophole would allow it.