obsrvr

Your right to remain silent (in the USA) should include the devices one communicates with, as the Miranda warning makes it clear that "anything you say CAN AND WILL be used against you."  In fact, it starts out with, "You have the right to remain silent."  That Constitutional right means that you cannot be forced to reveal evidence of any type, whether or not that could lead to your successful prosecution.  If the prosecutor can find a reliable witness who will testify against you about what you allegedly said, they have done their work correctly, one assumes.  But they cannot force you to tell them whom you might have told something incriminating, because the point is that they cannot force anyone to contribute to their own prosecution.  If that were the case, waterboarding might be a lot more common at the cop shops around this country.  They are allowed to trick you, they can lie to you, they can try to trop you, but they are not allowed to forcefully compel you to reveal information that may be used against you.  Just never tell them your password, and don't rely on your thumbprint alone.  They can get that, legally.