Make-shift Oil Lamp

Bruce Pandoff — Mon, 02 Apr 2012 04:39:49 +0000

A simple oil lamp can be made from numerous materials found in the bush or around the home.

Sustaining light away from the fire or when the power goes out may be difficult especially if candles are not on hand. This is an easy solution of using spare oil or rendered fat to keep the lights on when the rest of the world goes dark.

Many different containers could be used to hold the oil. In this case, we will be using a scavenged clam shell for holding the oil. A spoon, a tin can, a soda can, ceramic bowl, or anything nonflammable and not at risk of melting could be used. The wick could be made from a piece of cloth, a rag, a twisted paper towel, or just about anything that will soak up the oil. The oil can come from “waste” cook oil that has dripped off into the cook pan as is the case here. One could also use olive oil or vegetable oil as a fuel or from rendered fat in the bush.

Here we use a clam shell as the container for the oil

Next, some cedar bark is acquired to process into the wick.

Processing cedar

The cedar wick is then made by using the reverse wrap cordage making technique

Add some rendered fat (oil leftover from cooking) and the cedar wick soaks it up

The wick is lit with a match and the shell oil lamp will burn for about 30 minutes on one filling. It can be increased by adding more oil or rendered fat.

The same method could be done with more modern tools or scavenged goods such as a soda can and a piece of reverse wrapped paper towel.

Field Expedient Encryption – Part One

H-Minus — Wed, 22 Jun 2011 23:49:31 +0000

The power has been out for the three months. No one knows what happened. The stores ran out of food after the first week. The water stopped flowing soon after that. Many large towns and cities are becoming uninhabitable. There is no law and no one to call for help. There is talk of terrible atrocities being committed by armed gangs.

You are lucky, your town happens to be remote enough and small enough to manage the chaos. Folks from all walks of life are pulling together to make the best of this difficult time. An ad-hoc committee was elected to represent the town and you have been asked to help with security. Agreements were made to help a local farmer protect and harvest his crops in return for a share of the food.

You have one problem. Although you have a decent security program, you worry about using the handheld radios. A few nights ago, one of the checkpoints could hear some chatter on the same frequency. Your radios are not the expensive ones with “secure” frequencies. You worry that if you can hear others, then others can hear you. Some of the information passed to shifts is sensitive to the security needs of the community. How do you pass on information without risk of interception?

Today, you were discussing the possibility of bad guys listening in on your conversations, when someone mentions cryptography as a solution.

Now the old days in the military started flashing in your head… yes… we had this thing called a CEOI (Communications-Electronics Operating Instructions).

This person claims you can use a variation of the Vernam Cipher. A Vernam Cipher allows for the substitution of a plain text message with a random series of text or numbers from a “One Time Pad”. The resulting encrypted message is secure enough to be sent over the airwaves, without risk of being deciphered by an interceptor. Once it reaches its destination, the intended receiver will use the same “One Time Pad” to “unmix” the message.

A true Vernam Cipher, if used properly is thought to be unbreakable. The reason is because the cipher key constantly changes. This randomness makes it very difficult to decipher.

A poor mans version of this type of cipher can be something simple like a book. Each person intending to receive the secret message uses the book as a tool for decryption. As long as the bad guys don’t know that you are using the book as a tool, you should be secure.

Lets say you wish to send the following message over the radio to a friend:

GET BACK TO THE BUILDING

Using a book as a “One Time Pad” you simply look for each of the words in the book. As you find a word, note the page number, line number and word number in the line.

For simplicity, we will choose words all on the same page. “GET BACK TO THE BUILDING” encrypted will look like this:

11-1-25 / 11-32-8 / 11-1-10 / 11-8-2 / 11-7-7

The first three numbers (11-1-25) indicate the word you are looking for will be on page 11, line 1, and word 25.

You simply conduct this find and replace operation with each sequence of numbers. What you end up with is a message.

“Get back to the building”

Although this type of cipher is not a true Vernam Cipher, it will work as a field expedient method of secure communications. That is unless the bad guys find out what you are using for encryption. To keep them from figuring this out, never mark inside the book or leave any trace of encrypted messages in the book. If any of these clues were left in the book, it wouldn’t take much for the bad guys to figure it out.

The next article will dicuss a slightly more difficult, but secure version of the Vernam Cipher.

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Make-shift Oil Lamp

Field Expedient Encryption – Part One