Well, I posted the article, but don't necessarily ratify the content.  However, I have never had much confidence in the RF (radio-frequency) security of computers.  That point was driven home to me in mid 1977, when I built a microprocessor-trainer board called a "Dyna Micro"  http://en.wikipedia.org/wiki/Single-board_computer       It was uncased, and I ran it near an AM/FM radio.  While listening to the AM band, away from an active station, it made numerous audio sounds as it went through the program of the keyboard scanner and programs that I entered.  It was obvious that information could be transfered by RF, although at the time I wasn't particularly concerned about the possibility.
In about 1983, I visited Washington DC, and attended some sort of military electronics convention (invited by a customer of my company, SemiDisk Systems, Inc) and I was introduced to the concept of "Tempest" shielding. 
In the summer of 2002, while a guest at the "Gated Community" of USP Atwater, California, I worked for the Federal Prison Industries ("Unicor") tearing apart electronic hardware, mostly computer monitors.  I was the only person there, either prisoner or staff, who understood what the parts were which were on the boards.  Very rarely, a computer monitor came through which I recognized was a shielded, "Tempest"-grade monitor.  
        Jim Bell

From: Cypher <cypher@cpunk.us>
To: jim bell <jamesdbell9@yahoo.com>
Cc: "cypherpunks@cpunks.org" <cypherpunks@cpunks.org>
Sent: Saturday, April 5, 2014 12:34 AM
Subject: Re: Acoustic bugging of computers

>I saw this a while back and really question it's usability. While it's *technically* possible, it seems far to complex >for the average hacker and far too risky for the intel community.  People who use encryption tend to be slightly >more paranoid than the average user. Suddenly receiving a piece of encrypted, nonsense email might be >enough to get their key. But I also suspect that, in many cases, that key would quickly be revoked and >reissued. 

>Sent from my mobile device


On Apr 5, 2014, at 0:44, jim bell <jamesdbell9@yahoo.com> wrote:



(Phys.org) —A trio of researchers in Israel has discovered that it is possible to crack 4096-bit RSA encryption keys using a microphone to listen to high-pitch noises generated by internal computer components. Adi Shamir (co-inventor of RSA), Daniel Genkin and Eran Tromer have published a research paper describing the technique on a Tel Aviv University server.

Read more at: http://phys.org/news/2013-12-trio-rsa-encryption-keys-noise.html#jCp
Computers make noises, the researchers explain, far beyond the whirring of the fan. The CPU, for example, emits a high pitched noise as it operates, fluctuating depending on which operations it is performing—other components do likewise. Suspecting that they might be able to exploit this characteristic of computers, the researchers set about creating software to interpret noise data obtained using simple microphones and very little other equipment. They also focused exclusively on trying to achieve one single feat: deciphering an RSA encryption key. After much trial and effort, the researchers found it could be done without much effort.
Listening and detecting the noise made by a computer as it processes a single character in an encryption key would be impossible, of course, so the researchers devised a method that causes the noise to be repeated enough times in a row to enable capture of its signal. And that can only happen if the attacker is able to send a cyphertext to the machine that is to be attacked and have it processed. The cyphertext contains code that causes looping. By listening to how the computer processes the cyphertext, the researchers can map the noises made by the computer as it crunches different characters, thereby allowing encryption keys sent by others to be cracked.
What's perhaps most frightening about this method is how easily it can be ported to various machines. The researchers found, for example, that by using a laptop and simple hardware and software they were able to crack encryption keys on a second laptop. Next, they did the same thing using a cell phone as the listening device. They suggest it could also be packaged completely in software and sent out as malware, hacking encryption keys on infected devices and sending them back to the hacker.
As a side-note, the researchers also found that low-bandwidth attacks on computers are also possible by measuring the electrical potential of a computer's chassis while the circuitry is busy doing its work.
More information: RSA Key Extraction via Low-Bandwidth Acoustic Cryptanalysis: www.tau.ac.il/~tromer/papers/acoustic-20131218.pdf