Code Talking using the Vigenere Cipher Method

US Crow – by Ron Hardin

Throughout the Nation today the Militias are forming. They are ceasing to be rag tag strangely dressed guys and gals sitting around discussing what they will do when TSHTF. Today’s Militia are becoming tactically proficient, hard charging, maneuver units with a mission. The more people you put under arms the more communications are needed. Secure Communications that is.  

Militia COMSEC

I was having a one on one with a friend last week when the subject of Comsec came up. COMmunications SECurity is the word in discussion. We were trying to hash out how millions of Militia members could all afford the new Self Encryptable radios. We both agreed that would be a non-starter. So how will we talk? He favored using small IPAD or Laptop computers to encrypt the text then handing it off to radio guys to transmit either by voice or by Morse Code. Here is what I said:

During the 60′s and 70′s our Spec Ops teams in Nam used Morse code as the basic communications links. They used one time pads and Tri-graphs in conjunction with protocols for how and when to transmit. You can hardly ever be identified while listening. He had a puzzled look on his face so I told him what follows.

To send information on an open frequency you have to break the data down to the smallest possible groups. In the one time pads there were 5 groups of 5 letters on each line. If the operator is sending 20 words per minute at 5 letter per word it took 1 minute for 100 characters to be transmitted. It takes about 2 minutes of sending in those days to get an 8 digit grid square for your location. That is about 2 HE rounds from a cannon sitting 5 to 10 miles away.

To keep the signal short they used a system where the operator keyed the morse digits into a small tape recorder. Then the recorder would play back the signal at 7 times the original speed. Kind of like recording at 1 7/8″ per second and playing back at 7″ per second. This still left a lot of time on the air for it to start raining steel. So high power transmitters from out of range would clutter the frequency up until the last second. Then the team transmitted their burst of generally 3 minutes, and the interference kicked back in on cue. Still we lost a few.

The enemy though would generally prefer to intercept the message and try to decrypt it than waste ammo in a vacant by then lot since the operator would climb a tree, drop an antenna out,send the data, pull up the antenna, and slip down and beat feet before the rounds were due in. They could sit in a thicket later and receive their answer on another frequency.

Code Talking using The vigenere Cypher Method

The key to all this was the vigenere. The vigenere was a device that dates back to the Greek and Roman wars period. The encryption was comparable with a computer running 16bit program.

Its main advantage was it could be used without any equipment. Most of the Operators had this vigenere in their memory and only needed the two variables to write their coded message.

The vernier is a 26 by 26 chart. You start on the left top with the letter A and go down the left side with the alphabet in order to Z. To go across the top for the same A to Z to create a 26 by 26 chart. succeeding lines each followed the plan till you had 26 rows of 26 letters. When you ran out of letter before you reached the end you started over with A and on. This is the vigenere.

Vigenere Cipher

The second part is a one-time Pad. This pad consists of a series of three lines of 5 letter 5 group spaces. You start on the first line writing your message on the spaces. If it goes beyond the 5 groups the next letter goes on the first space of the next three lines. Most operators break the lines groups by drawing a line.

Once the message is written you start on the Second line of the first group and begin inputting from the encryption sheet on the onetime pads. These encryption sheet pads though can be replaced by a shared document. In Nam the teams used John 3-16 when the pads were lost or compromised, and they needed to make contact for more. The spaces are filled in to the end of the message.

To encode you find the letter on the first line first space on the left side of the vigenere. Then come across the line to the letter on the second line. Then go to the top line and write that letter in the first space of the third line. This is the letter that will be transmitted.

Decoding is done in reverse. However you can swap if you want to so long as all know about it. The key is the three locations. Good operators could read the clear message and send the encrypted code in their heads. Not a good practice in case you screw up.

This system is good because all of this can be done in your head in case you are in a POW camp, Jail Cell, or behind enemy lines. If they make you talk it matters not because once you miss a check in the encrypt key is declared compromised and destroyed. In your head is only the vigenere and John 3-16. When that is used all know it is a possible agent and take the appropriate actions to correct the situations.

So as we prepare for the coming bad times we need to learn a rudimentary knowledge of Morse code, and know how to make a vigenere and a Tri-graph. Knowledge of John 3-16 should not be left out of our skills.