I was tentative because the direction that two centuries of case law has taken the bill of rights often surprises me.

Thanks for the link. I googled for a bit to see if there had been a decision by the Massachusetts Supreme Judicial Court, but it doesn't appear so.

I watched a bit of the oral argument [1] from last November, and the state's argument was that since they were only asking for an order for the defendant to decrypt the data (not hand over the decryption key), the the defendant's 5th amendment rights would not be violated.

[1] http://www2.suffolk.edu/sjc/archive/2013/SJC_11358.html