> There are no controls because there is no possibility of controls, as a matter of mathematics. This is kind of true because, for example, the one-time pad is

> There are no controls because there is no possibility of controls, as a matter of mathematics. This is kind of true because, for example, the one-time pad is information-theoretically secure, and anyone could choose to use a one-time pad with anyone else given prior arrangements. Or anyone could choose to use RSA for confidentiality with anyone else given a mutual desire to communicate confidentially and an authentic but not confidential channel. However, there's nothing mathematically stopping a government from punishing people who are observed to follow a protocol to create a confidential channel. Although Eben Moglen has argued that the right to speak PGP is the right to speak Navajo, a government could conceivably choose to punish people for speaking a foreign language. One might wish (I would certainly wish) that people would be extremely upset by this, but I guess it wouldn't contravene mathematics. In fact, there are some historic cases where populations were subject to official military censorship in wartime, which included overt government review of some of their communications, and possibly a prohibition on the use of "codes", and sometimes restrictions on the use of foreign languages. One might again wish that this would be both much less acceptable and much less feasible now than in the past, but it's not completely impossible.