"Agent Hammer's" English Translation of Robin
Lobel's TEMPEST paper
Note from the translator: "I just don't have a mastery of the English words and don't know this stuff well enough to make them up.
I think you will be able to decipher my crazed translation though. It doesn't look like they
got all that they wanted out of their experiment...rather they weren't able to finish it. I get the impression
they had to turn in their report before they were done. Its clear to me that these were students in a professional technical high school/ community
college type setting."
Introduction:
1.
Definition and basic information
When an electronic device is used, it sends out electronic
waves that can stretch several meters out into the surrounding environment.
When these waves are captured, they can be used to reproduce the
information contained within them. These
waves are called “jeopardizing waves” because they put the information that
is contained within them into jeopardy. This
is true for all kinds of electronic devices.
These waves can theoretically be captured and allow us to read even the
most secretive information. Nevertheless,
the amplitude of the waves diminish quickly, making it difficult to capture them
for more than a few centimeters from the initial signal, thus it is difficult to
capture signals from most devices. Computer
screens, however, send out signals 500 times stronger than the initial image the
video card sends out, thereby sending out waves at a an amplitude strong enough
to easily capture them.
2.
Proof that the phenomenon exists
If a computer screen is plugged into a central unit with a
non-reinforced cable, an echo effect will take place as well as a delayed
reproduction of the original image on the computer screen.
The cord acts as a receiving antenna, capturing the waves from the
antenna and transforms them into electronic waves sent to the screen.
3.
Objective
The objective of this report is to prove that the
phenomenon of “jeopardy” exists, and to attempt to understand under what
conditions and at what cost it is possible to reproduce images on a computer
screen
I. History of TEMPEST
A historical summary of TEMPEST is presented.
They summarize how and when Tempest began, previous names of what is
currently called TEMPEST and discuss attempts to get declassified information
about TEMPEST. Most attempts have
failed to produce satisfactory results. The
latest attempt in 1999 produced severely censored documents about TEMPEST.
There is very little detailed information available about this system.
II.
Theory of Screens
1.
Deconstruction of an image
All colors can be broken down
into three fundamental colors: red, green and blue.
Using variations of intensities in the combinations of these colors, any
other color can be created. An
image is considered a complex assembly of colors through the use of a pattern of
“pixels”. A pixel is a point
composed of three colors, red, green and blue.
By increasing the density of pixels in a single area, it is possible to
recreate accurate images. The
resolution of an image is represented by the formula X*Y with X being the number
of horizontal pixels and Y being the number of vertical pixels (ex:
640*800, 800*600, 1024*768…)
2.
Reproduction of an image on a screen
A screen is composed of several
modules. The cathode tube is what
reproduces the actual image. An
electron beam scans a fluorescent layer at an extremely high speed, creating the
image. The scanning goes across the
entire screen from left to right and from top to bottom at a frequency of 50-100
Hz. As the electrons pass through
the fluorescent layer, it sends out a light. This layer also becomes phosphorescent in that it continues
to send out a light after its initial stimulation for approximately 10-20 ms.
Its brightness is determined by the debit in the electrons, which is
regulated by a “wehlnet”. The beam then passes through two bobbins that determine its
trajectory through electromagnetic forces, and an image is then scanned onto the
screen.
3.
Coding of the video signal
The video signal passes through
several channels: 6 channels for
the video signal itself. Meaning,
the Red, Green and Blue channels as well as their respective masses; 2
synchronization channels for the horizontal and vertical scanning and the
communal mass of synchronization signals. The
synchro signals are simply the difference in a few voltage potentials.
They take place 70 times per second for vertical synch (for a 800*600
resolution screen cooling at 70 Hz) and 70*600=42000 times per second for
horizontal synch.
Video signals are at a voltage of
0 V to .7 V, which defines the brightness at the point where the scanning takes
place (this voltage tends to change depending on each new pixel color.
For an 800*600 res screen with a cooling of 70 Hz, the changes in voltage
can go all the way to a frequency of 800*600*70= 34MHz, or 34 000 000 times per
second).
III.
Theoretical Expansion on Circuits
1.
Circuit Demands
Earlier, we learned about the
nature of the electrical signals that, through amplification, drive an image
toward a screen. As a result of
this amplification, the“jeopardy waves” that we are attempting to capture,
are created.
For every difference in potential
that is created at the exit of the amp circuit, an electromagnetic wave of
proportional amplitude is emitted. The
amplitude of this wave diminishes as the electromagnetic energy spreads across
the front of the spherical wave.
(graph)
An oscilloscope shows us that
the image on the right is deformed by the absorption of the wave linked to the
horizontal synchronization signal (center); note that the signal oscillates on
the y-axis because of disturbances in the supply. We want to capture the video signal at left.
Based upon what we have
demonstrated earlier, this image is not directly exploitable on a screen because
we need a positive signal whose voltage is between 0 V and .7 V.
The solution must allow us to
cancel out the signal created by the synchronization signal and the supply while
amplifying the signal.
In an effort to eliminate
parasitic signals, we create an open (???) circuit between the receiving antenna
and the screen. There are two types
of circuits, high band and low band, which will allow high and low frequencies
through them. In our case, we
need a high band circuit because the video signals (several 10’s of MHz) are
higher than the synchronization signals (several 10’s of KHz for horizontal
synchronizations).
Drawing
The drawing, through the use
of a condenser and resistance, creates a high band filter.
Essentially, all signals can be
considered as the sum of the sinusoidal signals. Consequently, the high band filter can “suppress” the
components whose frequencies are less than the frequency of the breaker (??).
When the high band filter is
exposed to a sinusoidal voltage (tension), the condenser takes a charge.
Then, when the sinusoid changes variation and direction (??), the
condenser discharges. However, if
the voltage period is superior to the charging period, the condenser will react
like a circuit breaker and impedes the signal’s passage.
One can vary the frequency of the breaker by adjusting the values of
“C” and “R”. Suppose t=RC.
If t
increases, the charging period on the condenser increases and therefore the
frequency of the breaker diminishes.
On can deduct from this that the
frequency of the breaker fc
is inversely proportional to t=RC.
We then have:
fc =
1/2pRC
One can then deduct how the
voltage will appear as it exits the device relative to the voltage as it enters
the device.
If the frequency at entry fe is higher than the frequency of the breaker, the condenser takes a positive charge then a negative charge. On can thus write the equation of the voltage at the circuit terminals RC:
-t/t
Us
= sin (fet).(1-e
)
On can therefore trace the voltage at the circuit terminals RC relative to the frequency of the voltage at entry.
(Graph)
As such, if the voltage at entry is the sum of two (or more) signals, one of which is higher in frequency than the breaker and the other of which is lower than the breaker frequency, all that will emerge will be the frequency signals that are higher than those of the breaker:
Graph
One notes that the exiting
signal (yellow) is “almost” the same as the frequency signals that are
higher than the breaker signal (blue). It
is slightly deformed. In green, the
entry signal – the sum of two different frequency signals
To have an exploitable signal, we
need a signal that is between 0V and .7V. It
must therefore be amplified, but the proportion of the difference between
signals must be preserved. To do
this, we must therefore multiply the voltage exiting from the RC circuit by a
factor of k. For this, we chose to
use a circuit based on an Operational Amplifier (O.A.), referred to as an “inverser”.
Drawing
An inverser circuit that
amplifies the entry voltage by a factor of k
In such a circuit, we see that
Ohm’s Law applies to the resistance R2. This then reduces
the voltage entering the operational amplifier; the voltage Ur
is therefore less than Voltage Ue.
The Voltage Us is therefore proportional to the value of
the resistance R2.
The resistance R3
is in diversion with the OA; the more its value increases, the less current will
cross it and therefore more current will cross the OA, knowing that i1<i2. On
deducts from this that the exit voltage is proportional to the value of R3’s
resistance.
One notices that the set up is
reversed (entry on the negative terminal and grounding on the positive
terminal). The exit signal is
therefore multiplied by a negative coefficient, hence one can deduct that:
K = - R3/
R2
By regulating the values of R2
and R3, we are able to vary the voltage at the terminals of entry on
the Operational Amplifier. The OA
will then multiply the voltage of the entry signal (through stable feeding from
the V+ and V- terminals).
The recuperated signals are de-synchronized. The screen cannot therefore recreate coherent images. We must then, send artificial synchronization to the screen. To do so, we can use two methods:
§ Generate a signal with the use of two GBF (one for the horizontal synchro, the other for the vertical)
§
Capture signals emitted by the graphic card in a functioning
computer
The first option appears to be
most appropriate because it allows for changes in order to adapt the synchro
signals to the received signals.
Because of the fact that a wave
is only emitted for each different voltage in the screen, the obtained image
cannot be an exact replica of the first image.
But it will allow access to the information posted on the original
screen. In theory, one would obtain
an image something like this:
Picture
IV.
Experiment
1.
Choice of values for the high band:
As we saw earlier, we would like
to eliminate the effects of the synchro signals. These signals repeat themselves at a frequency of around
70*600 = 42KHz (for a screen of 800*600*70Hz, taking into account the horizontal
synchronization). We choose a
slightly higher value for the breaker frequency of fc to assure a margin of safety and eliminate a
maximum number of parasites. One
therefore chooses a neighboring breaker frequency of 160 KHz:
ƒc = 1/2pRC
RC
= 1/2p
ƒc
RC
= 1/2p.160000
–6
RC = 10 s
We must therefore choose an RC
relationship around 10 –6s. At
this point, the condensers represent their maximum values in micro Farad (mF).
The resistance employed must therefore be represented by a kilo Ohm (kW).
a.
Choice of Operational Amplifier models:
For our experiment, we need an
operational amplifier capable of supporting significant frequencies nearing
50MHz. To be safe, we have chosen
an OA that can handle closer to 60 MHz. We
are therefore in the realm of OA’s that are uniquely created for video
production. The model we selected
is the AD844AN. This model needs a
stable feeding of 5V and a maximum voltage entry of 5 mV.
b.
Choice of resistance values
Our Operational Amplifier choice
necessitates strong resistance values such that the entry voltage can be 5 mV.
To obtain such a large resistance value, we assert the following:
A voltage is a difference in
electrical states, or the difference between two potentials.
The weaker the gap, the weaker the voltage!
Drawing
Our goal is to choose a
resistance that allows us to have a voltage between 3 and 5mV.
The wire on the positive terminal is connected to the ground.
Its potential is therefore zero. We
will therefore need a potential of 5mV
from the wire on the negative terminal. This
value is extremely weak near an entry potential (about .1V).
When adding a large resistance, we obtain a strong voltage at the
resistance terminal (Ohm’s law) and therefore a weak potential at the lesser
terminal. We will therefore choose
a resistance variable, R2,
of 1 W
(Ohm).
We witnessed the amplification
relationship earlier. Knowing that
we want to amplify in a block of 1 to 100, we will need a resistance, R3,
somewhere between 10 and 100 W.
Photo
The original signal (green,
-3V) and after amplification (+5V).
V.
Results
At the point of writing this
thesis, our experiment has not yet been completed (although we do have all the
necessary components to make it happen).
Our most encouraging results that
we have obtains thus far are below:
2 Photo
The original image is on the
left. At right the 2 central pics,
captured electro magnetically, correspond to the beginning and end of the white
band.
The signal on the right was
obtained thanks to a high frequency filter, which demonstrates its
effectiveness. We now have simply
to amplify this signal and transmit it to a second screen that we will
synchronize with the help of 2 GBF’s to create a ghost image, similar to the
original image.
We had several problems with the operational amplifier (most notably the resistance) but these were eventually resolved (as is evidenced by the image on the previous page.