[Cryptography] Tempest and limits on receiving

[Jon Callas]

In the US, the 1934 Federal Communications Act allows anyone to listen to any frequency that is not specifically blocked. This isn't the case in other countries.

There are relatively few specifically prohibited frequencies, but those used by cellular communications are on the list. This is a result of someone mostly inadvertently picking up conversations between Newt Gingrich and a number of colleagues including John Boehner and others. The group of them were discussing ethics charges against Gingrich, and they were intercepted by people with a scanner who were playing around and just happened to pick up Boehner's car phone.

Here's an article from the time period by John Markoff

http://www.nytimes.com/1997/01/19/weekinreview/at-the-new-frontier-of-eavesdropping.html

Here's a PBS News Hour article:

http://www.pbs.org/newshour/bb/politics-jan-june97-cellular_01-14/

As others have noted, this has nothing to do with TEMPEST and is arguably the opposite of TEMPEST, but the upshot is that in the US the default is that you are allowed to listen, except when there is an explicit carveout. 

	Jon