One hundred years ago, Louis Brandeis and Samuel Warren warned us that, "Numerous mechanical devices threaten to make good the prediction that 'what is whispered in the closet shall be proclaimed from the housetops.'" Cryptography is an enabling technology for self-help privacy. Conversely, cryptography can be used to conceal criminal conspiracies and activities, including espionage. How have computers changed the ways in which we have to keep certain information private? What new threats do computer systems and networks pose to personal privacy? Conversely, what threats are enabled or enhanced by computer systems and networks? How does cryptography help or hinder protection of privacy and public safety? What policies are needed and appropriate in a networked world regarding the use of cryptography?