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”

tapir

YKX XBC XIO GGG EEE QQQ =

___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.

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.

TIARA GNOME- An Episode in the History of Cryptography

TIARA GNOME

Below we can see the captured traffic of a momentous message sent from Tokyo to their Embassy in Washington, DC just prior to the attack at Pearl Harbor.  This HF message was captured, but that did little good to prevent the attack.  “OBESE OVALS” stands for the government office in Tokyo that sent the message.

S352/6 1000S GR265
OBESE OVALS TIARA ..OME
62527 ZTXOD NWKCC MAVNZ XYWEE TUQTC IMNVE UVIWB LUAXR RTLVA
RGNTP CNOIU PJLCI VRTPJ KAUHV MUDTH KTXYZ ELQTV WGBUH FAWSH
ULBFB HEXMY HFLOW D-KWH KKNXE BVPYH HGHEK XIOHQ HUHWI KYJYH
PPFEA LNNAK IBOOZ NFRLQ CFLJT TSSDD OIOCV T-ZCK QTSHX TIJCN
WXOKU FNQR- TAOIH WTATW VHOTG CGAKV ANKZA NMUIN
YOYJF SRDKK SEQBW KIOOR JAUWK XQGUW PDUDZ NDRMD HVHYP NIZXB
GICXR MAWMF TIUDB XIENL ONOQV QKYCO TVSHV NZZQP DLMXV NRUUN
QFTCD FECZD FGMXE HHWYO NHYNJ DOVJU NCSUV KKEIW OLKRB UUSOZ
UIGNI SMWUO SBOBL JXERZ JEQYQ MTFTX BJNCM JKVRK OTSOP BOYMK
IRETI NCPSQ JAWVH UFKRM AMXNZ UIFNO PUEMH GLOEJ HZOOK HHEED
NIHXF XFXGP DZBSK AZABY EKYEP NIYSH VKFRF PVCJT PTOYC NEIQB
FEXME RMIZL GDRXZ ORLZF SQYPZ FATZC HUGRN HWDDT AIHYO OCOOD
UZYIW JROOJ UMUIH RBEJF ONAXG NCKAO ARDIH CDZKI XPR– DIMUW
OMHLT JSOUX PFKGE PWJOM TUVKM WRKTA CUPIG AFEDF VRKXF XLFGU
RDETJ IYOLK BHZKX OJDDO VRHMM UQBFO WRODM RMUWN AYKYP ISDLH
ECKIN LJORK WNWXA DAJOL ONOEV MUQDF IDSPE BBPWR OFBOP AZJEU
USBHG IORCS UUQKI IEHPC TJRWS OGLET ZLOUK KEOJO SMKJB WUCDD
CPYUU WCSSK WWVLI UPKYX GKQOK AZTEZ FHGVP JFEWE UBKLI ZLWKK
OBXLE PQPDA TWUSU UPKYR HNWDZ XXGTW DDNSH DCBCJ XAOOE EPUBP
WFRBQ SFXSE ZJJYA ANMG- WLYMG WAQDG IVNOH KOUTI XYFOK NGGBF

Symmetric Warfare: Using Code Words to Send Unobservable Messages

Using code words in a normal-looking message is a cheap and effective way to communicate. 


Scenario:

Several American businessmen are in Kuala Lumpur, Malaysia trying to get a contract signed for a lucrative mining deal. Mike, the head negotiator, communicates with his iPhone over a 3G GSM network, and he uses his corporate e-mail account via his laptop.

Before he left home he came up with a series of code words to use when he communicates with his boss. This simple and cheap method defeats and misleads national-level eavesdropping, hackers, competitors who eavesdrop, and everyone else who wants to spy on him. Just keep your special word list safe. Beware of thinking that old school is somehow wrong, or that it offers flimsy security. The opposite is true. Flying under the radar is a very good idea these days, and simple is good.  He printed his little code word table on a piece of paper and he hid that paper inside his wallet.

Here is the code word list for the above scenario:

SPECIAL WORD(s)                                           MEANING

NORTH                                          THE BUSINESS DEAL DID NOT GO THROUGH

SOUTH                                          THE BUSINESS DEAL DID GO THROUGH

EAST                                             THINGS LOOK PROMISING BUT NOT YET COMPLETE

WEST                                             HUGE SUCCESS

NORTHEAST                                 UTTER FAILURE

NORTHWEST                                 WE NEED MORE TIME

NICE PLACE                                   WE ARE BEING WATCHED

GOOD RESTAURANT                    PROBABLY WE ARE NOT WATCHED

CHINESE                                        THEY SIGNED THE CONTRACT SECRETLY WITH US

JAPANESE                                      THEY REFUSED TO SIGN THE CONTRACT

INDIAN                                            THEY SIGNED THE CONTRACT WITH US OPENLY

THAI                                                THEY ARE NOT CORRUPT

WRITE YOU TOMORROW             OTHERS ARE OFFERING PERKS

CALL YOU TOMORROW                WE HAD TO OFFER SOME PERKS

One can then write a misleading message containing special words with special meanings.   So here is the letter Mike writes:

John,

I am very sorry to say that the deal did not go through. We are extremely disappointed by the behavior of their people. Tonight we are going to take a break after all these days of hard work. We are going to that Chinese restaurant west of here that you said is a nice place. Call you tomorrow.

Mike


Come up with traffic that sounds reasonable given the realities of the context. In the scenario above one could expect that a Chinese, Thai, Japanese, or Indian restaurant really does exist west of the speaker’s location. Tell everyone else involved in the business transaction to stay mum over the deal, and tell them to be especially careful over the phone or on the internet. Best practice would be to assure that as few people know about it as possible. Only those who need to know should be told about it.

The message and code word table above is for a specific purpose.  A longer table can be the basis for extended conversations on varying subjects.  Keeping the code word table secret is a priority.  One can write it down, one can print it at home on a small piece of paper, or one could encrypt it with a 4096 bit PGP key and use it on a computer that is never attached to the internet.  This last course of action is the least recommended.

And yes, if the situation is that bad, find a Chinese restaurant west of you and have dinner after you send your fake message.

The point of all this is that simple human means can defeat elaborate mechanical threats.  It does not take high technology to defeat the masters of high technology.  It simply takes a little thoughtful effort.