IB  Ingrid Bergman in the 1944 film “Gaslight”

“…the Stasi often used a method which was really diabolic. It was called Zersetzung (gaslighting). The word is difficult to translate because it literally means “decomposition.”  But actually, it’s a quite accurate description. The goal was to secretly destroy the self-confidence of people, for example by damaging their reputation, by organizing failures in their work, and by destroying their personal relationships. Considering this, East Germany was a very modern dictatorship. The Stasi didn’t try to arrest every dissident. It preferred to paralyze them, and it could do so because it had access to so much personal information and to so many institutions.”
—Hubertus Knabe, German historian

One of the problems with en masse surveillance is that gives a government the power to psychologically attack anyone whom they do not like.  This has happened before, and it is happening now in some places. The STASI perfected gaslighting, and this perfection was based on their eavesdropping against the population.

A Sample Table of Trigraphs and Meanings

Sample Trigraph Code Table

Using bigraphs or trigraphs can offer a high level of privacy.  Use bigraphs for brevity.  Trigraphs are usually used when your code table is long, but this is not always the case.

Sending code messages like this can be done via Vernam Cipher (one time pad).  See the STASI “TAPIR” with its indicator for sending code (“84”).  In this example we will send a trigraph message encrypted with a one time pad (OTP) for optimal privacy.

For example:

Your message:  protest meeting success, being watched at this location, do not contact

Or:                       XBC XIO GGG EEE QQQ

Header:       YKX

Header +  Your message:         YKX XBC XIO GGG EEE QQQ

Encoded with the STASI (Ministerium für Staatssicherheit) code table “TAPIR”



___plain text ____________78617 78377 50528 37726 48357 57578 31118 36868 6883


     key                                          13698 93797 05536 49550 66877 17941 11148 70355 75933 94896


____cipher text___________81205 61064 55054 76276 04124 64419 42256 06113 3376

Notice the Modulo 10 system of addition (one adds without carrying over)

You and your corespondent both have the one time pad key, and you both have the same code table (TAPIR in this case) and the Trigraph table.  In this message we did not indicate that it would be code.  But one could do that easily by inserting “84” after the header (prior to encryption).  In this case both corespondents already knew that the trigraph code table would be used.  The benefit of this system is that the message is not going to be broken by computational attack, and that the string of numbers in the ciphertext (in the message one will send) can be hidden.  The header (YKX) indicates which key to use, and successive headers should not be sequential.

Listening In- A Vietnam Vet Talks About Signal Collection in Combat Against the VC

Recently in Bangkok RGP had the privilege of sharing some cold barley soup with a US Vietnam War veteran.  He talked about collecting push-to-talk radio signals against the NVA and VC.

He said that in the very beginning of the war they had some success.  He said that one develops a sixth sense, that something did not feel right.  One night, he was feeling those little hairs on the back of his neck stand up, and so he went and turned on his radios and he noticed a very slight pop on one frequency, and so he waited.  Once in a while he heard a small noise on that one particular frequency and so he just kept waiting, listening.  He was in a small bunker with a candle, and the small noises became more frequent.  Then he heard a word, just one word, but he did not recognize it.  He said it was getting really late, and he just sat waiting, for hours.  The enemy was moving and keying the microphone by accident as they moved up.  He warned his Company Commander.  He said the small noises got clearer and clearer, and then when the attack started the voice was so clear that it sounded like that VC soldier was right there in the bunker with him.


The ICOM IC-R9500 (Know What is Going on Around You in the RF Spectrum)


What a beautiful piece of equipment!

This is a radio receiver.  Properly set up it will scan from .005 MhZ to 3.335 GhZ.  This tool will give you a clear idea as to what is going on in the electromagnetic spectrum around you.  Scans can be set up, and an external speaker can be attached.  Signals that you recognize can be ignored, and you can look for suspicious signals that pop up.

If you have something around you that is transmitting, something that you did not know about, then this might represent an invasion of your privacy.  A device like this can be used for many purposes.  The one pictured here is extremely sophisticated.  Others are simple and cheap.  The purpose of this device is not to do a technical survey of a room or series of rooms.  It would only be able to find rudimentary listening devices.  Its purpose is to see a big chunk of the spectrum as to what kinds of transmissions are going on in your area.  Although it is true that this receiver would pick up a radio signal coming from your computer if that signal was between .005 MhZ and 3.335 GhZ.  If your computer is sending out a radio signal (with your information) that you do not know about, then it is time to get a new computer.

This receiver will pick up all kinds of traffic:  am radio, HF signals, aircraft, push-to-talk radio, commercial radio, digital signals of many kinds, analog television (audio), encrypted signals (they will only be seen and a garbled noise will be heard), UHF radio, emergency beacons such as avalanche or downed-aircraft locating devices, etc.

psk_matrix2.jpg          PSK-31

The next step is learning about the electromagnetic spectrum and knowing how waves propagate and how they can be modulated.  Learning about the spectrum tells you what kinds of signals are possible at certain frequencies.

Also, one needs to be diligent because some signals only transmit at odd intervals or on unusual frequencies.

One needs to be aware of the legal aspects of using such a device.  Laws vary, of course, by country.  This device is passive, but one must be aware of, and follow, legal restrictions.  Hobbyists use such devices all over the world, but they usually have sections of the spectrum blocked off.  Make sure to follow your local laws.

There are many situations where a scanner like this would greatly enhance the security of a business or organization in hostile parts of the world, especially when this equipment is operated by attentive, competent personnel.  Small scanners can also reveal enlightening information.

Brochure for ICOM IC-R9500

A Table for Trigraph Code Words and Phrases

Blank Code Phrases Table

It is easy to make a table of words and phrases to make communication easier while completely masking the real meaning.  But one has to keep this table safe, and all correspondents will need to have a copy.  There are many ways to use the table.  Sending Vernam Cipher messages is one use.

Storing this table on a computer hooked to the internet defeats the purpose.