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.

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

Simple Means Can Succeed Against Incredibly Sophisticated Technology

Symmetric systems can sometimes offer unobservability. Sending hidden messages in routine traffic is always going to be possible. Imitating the whole system of routine traffic does not work because the task is too complex for the imitator. For example, a nearly perfect imitation of Skype can be detected very easily. Do not trust providers who promise you security based on the notion that their system fully imitates another system without being subject to attack.  It is better to send an encrypted message via a normal high-volume traffic route, like Skype, instead of using a service that tries to imitate a whole system with its immense complexities. Also, Skype is easy to use. Yahoo! is easy to use too.


Read the following message and try to guess if it holds hidden information:

Dear John and Teresa,
      How are you? I hope everything is going well.  Thanks for having us over! It was really nice to see you. Wow! That was the best barbecued chicken ever. An amazing dinner! I hope we can come back in October. Right now my work is a real headache. Fran is busy too. The kids keep our hands full. Especially Tommy. I hope the kids were not too much problem at dinner. And I am sorry Tommy broke that vase.
      Fran just got a new one. Please accept it. OK? She is going to bring it over next week. Please don’t worry. She is going to be in town for two days next week because of a conference, and it is easy for her to stop by. So give us a call this week if you can.
      Again, it was so fun to see you two again and I am really sorry about the vase. Hope to see you soon myself when work slows down. Things have been hectic. You can imagine. I have to work late just about every night. No time to do anything except get some sleep and show up back at work.
      Gotta run! Take care and see you both soon.

Adolf

There is a plaintext message inside the letter. Count the number of words in each sentence (after the greeting).

36571738846218631935080439527 (Plaintext)
In this system a sentence with 13 words resolves to a three. Ten words resolves to a 0.
Using a code pad somewhat similar to the STASI “TAPIR” the plaintext resolves to the following message:
MINEOWNERWANTSBRIBE
Mine owner wants bribe

So this message was sent in the clear (in plaintext).  That is not the best lifestyle decision.  Someone clever could guess you are communicating this way, and he could go to work to resolve your message by guessing the format of the code pad.  In fact, come to think of it, such an effort could be automated.  Simple code pads would be the most vulnerable.  But there is a solution.

The best way to send this message is to not send plaintext.  Send ciphertext.


Send an unobserved and unbreakable message with a random symmetric key

Gestapo 2.0 has arrived to your world, and you want to foil them.

1.  Decide on your message.

Message:        Go to the synagogue

2.  Use a code pad like the one below:

Gnome Code Pad 2

3.  Convert your message into numbers using the code pad.

65378378667557106536541

4.  Use a one-time-pad key designated by the greeting:

“Hey!”

“Hey!” equals key:

15423 89479 30985 95704 35770 95893 07814 10585 98524 24782 94553 89265 84302 52941

Both you and your correspondent have this key prior to the message being sent.  So you want to hide your one-time-pad keys.  You have to be careful that the Gestapo does not find your keys, but the huge advantage is that your message is not subject to computational attack.  They can look at it forever with a planet full of computers, but this will do no good at all.

5.   Add the plaintext to the key without carrying over.

Here is your ciphertext:

70791 16235 05456 91230 898

6.  Write your letter (Each sentence will have the number of words as in the ciphertext. Seven words, then 10 or 20, seven again, etc.  Contractions count as one word):

Hey!

My trip to Berlin was really fun.  The people there are so sophisticated and friendly and relaxed.  I walked around downtown all day long.  I have to tell you that it is beautiful.  Really!

Gosh.  Berlin has so many good restaurants.  Cheap too.  It was fun.  I want to go back.  One thing that stood out to me was how clean everything was, not just the restaurants, but the streets too. It is a vibrant city. I just love it. Maybe we can go together? I really enjoy the cosmopolitan atmosphere.

How have you been doing with your new studies?  Ok?  How’s Ben?  He’s so funny.  I hope that he can help you with your school.  I know he is a bright, diligent student.  Why not ask him again to help you out?

Maybe I’ll see you in a couple weeks!

Arthur


So you see that this method takes some time to create the story, to encrypt the message hidden in the story, and then to decrypt it.  Using a code table might be faster and easier for some messages.  Also, one can come up with one’s own methods based on the idea of hiding ciphertext in a normal-looking letter.  Both you and your correspondent need to have the prearranged set of keys, and the code pad.

One of the lessons here is that low-tech means can achieve high-end results.  If both correspondents destroy their key to this message after it is used, destroy it completely, then that is another plus.

Plaintext Injection Against Vernam Cipher

The Vernam Cipher key:

1.  Must be random.     2.   Must not be reused.    3.  Must not be compromised.   4.  Must be as long as the ciphertext.

Does plaintext injection into Vernam Cipher messages promise to reveal any important information about the key?  If an adversary can get you to put certain words into your message, then does that present a problem?  Does the collector gain any information about your key?

Even if:

1.  The ciphertext is captured complete

2.  The language of the message is known (which reveals frequency of digraphs and trigraphs and grammar)

3.  The message is not padded

4.  The format of the message is known (along with headers and Russian Copulation)

5.  The plaintext injection is certain to have occurred repeatedly over many messages

6.  The amount of presumed key code is large

None of these factors will help break the key as long as the key is truly random.

But if the key is weak such as being a passage from a book, then the weak key can become readily apparent, and any of the factors listed above will just accelerate the exposure.

STASI Vernam Cipher Table “TAPIR”

Cold War Encryption Systems (in German) Under “3.1 TAPIR” on the page linked to above one can download a WIndows .exe file and use a program to encrypt and decrypt messages the STASI (Ministerium für Staatssicherheit, MfS) way. Specifically, go to the line:  Programm: TAPIR Umsetzung für Windows per Download This file is compressed in the 7z format.  Go here to get the free download to open such files: http://www.7-zip.org/

Here we see the time tested and venerable “TAPIR” tapir

 

One-time pad cipher system    A digital picture of the card above

?????????????   A reworked version of the original “TAPIR”

Example of how these messages work:

1)  “Sicherheitsdienst Einzsatzkommando. Ostfront.”                -The message   (plaintext)

2)  Message transformed with the “TAPIR” table: 69253 14591 27069 54213 69708 31237 96907 07961 64636 30354 64828 98183 64697 95646 43708 28981 8383

+

-One Time Pad (key)

3)  Message will be encrytped with the One Time Pad below

64651 47703 77032 73245 23272 48788 31258 32815 85487 92553 67710 74204 43047 08318 60889 84435 78692 22960 85978 18412 36838 83027 73163 89243 68943 50392 29621 96950 70793 57365 58875 43986 53848 32228 32199 11014 17877 31116 91760 91366 17032 37177 90191 07652 36582 12960 96269 58905 22471 16963 21400 71763 30893 20974 46589 54063 90083 84253 54591 74336 91493 85185 96917 15605 52559 96840 50400 76941 18228 66881 42988 21217 93449 48066 53476 92474 23813 70158 14840 51375 66504 63508 75880 02146 18799 70229 00847 09464 96251 03907 11740 28727 77782 43779 02984 98137 59843 74340 83137 66038 _________________________________________________________________________________________________

4)  The result.  This is called the “ciphertext.”  This is the encrypted message now ready for transmission.

23804 51294 94091 27458 82970 79915 27155 39776 49013 22807 21538 62387 07634 03954 03587 02316 5142

This ciphertext is the core of the message.  Padding could be added to conceal its true length, and a non-sequential header could be added to identify which key should be used.  The message could be cut into two unequal pieces and those pieces could be switched.  This hides any salutations or common introductory phrases.  That method of dividing the plaintext is charmingly called “Russian Copulation.”

The point about this encryption system is that it is not susceptible to computational attack.

Some people may think think is merely a relic of history.  No.  This is the future.