Secure Method of Communication

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Secure Method of Communication Powered By Docstoc
					by: Max Penn


In today's business world, your business competitors will often try and get an edge over you by
any means possible.This includes attempts at intercepting your sensitive business

This is why it is highly recommended all companies, including yours, buy secure communication
equipment for sensitive business communications.

The problem...

But what happens when you're out of the office, you don't have your secure equipment with you ,
and yet you still urgently need to communicate sensitive information with a colleague...?

The solution...

The solution is having an alternative method of communicating securely by encoding your
messages. This system is called the one-time pad and is absolutely impossible to crack. Even the
biggest supercomputer of any one spy agency would not be able to accomplish this feat.

The only things required are a pen and a paper. Once encoded, you may send your messages by
mail, email, or even by phone.

Let's get started.


Step 1: Create the key...

The critical component of this system is the random key. A key is a series of numbers that is
used to take your original message (the plaintext) and turn it into a coded message (the

Before creating a random key, you need a way to convert alphabet characters into numbers.

Make a conversion table by taking a sheet of paper and writing letters and numbers as follow:

A    B C    D     E   F   G   H   I   J   K   L   M   N   O   P   Q   R

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18
S   T      U   V   W   X   Y   Z

19 20 21 22 23 24 25 26

You are now ready to create a key. First, write down a series of random alphabet characters, such

Break this long string of letters into blocks of two characters each, as follow:


Using the conversion table we've created above, convert the characters into numbers. For
example R=18 and T=20, so the first block HL becomes 1820. The result is 1820 0919 0523
2226 1725 0811 1516 0221 You have now created your first key. (Make sure to create a key
much longer than this so that you can send several messages before the key is used up.)

As you will use the block of numbers to encode your messages, you will cross out each block
you have used as to not use it more than once. (To simulate the crossing out of a block i will gray
the blocks as follow: 1820 0919 0523 2226 1725 0811 1516 0221 )

Create two copies of your key. One for you and the other for the recipient of your messages.

Step 2: Format your message...

Let's use an example.

If the message you want to encrypt is ACCEPT IT, you format this text message into blocks of
two characters each, yielding AC CE PT IT.

Next, convert the letters into numbers by using the conversion table above. In this example,
A=01, C=03, so the first block would be 0103. The entire string becomes 0103 0305 1620 0920.


Rule 1- Numbers. Spell out numbers in full in your plaintext. For example, 123 becomes ONE

Rule 2-The Period. Use an X for each period in your plaintext. For example, GOT YOUR

Rule 3-End of message. Add XX at the end of your plaintext message for termination. Spies
would add several bogus characters after the XX to make it even more difficult for code
breakers(those who tries to decode secret messages) by making them try to decode those
meaningless characters after the XX.
Step 3: Encode your message... We need a way to tell the recipient where the key begins,
otherwise he won't be able to decode the message.

Remember in our earlier example, we created a key and stroked off (in gray) the blocks we'd
already used.Here's what our key looked like. 1820 0919 0523 2226 1725 0811 1516 0221

The starting position in the key is at block 0919. So we will place the string 0919 at the
beginning of our message so the recipient will know how to decode.

The plaintext message of 0103 0305 1620 0920 becomes 0919 0103 0305 1620 0920 because we
place the pointer 0919 at the beginning of the string. We are now ready to encode our message.

First we write out the plaintext. Directly below it we write out the key. Then we add the key to
the plaintext using Fibonicci addition. This means we do no carrying. For example, 9 2 would
yield 1 not 11. And 7 plus 6 would yield 3 not 13. Here's how the agent's working sheet would

Plaintext 0919 0103 0305 1620 0920

Key            -- 0523 2226 1725 0811

Ciphertext0919 0626 2521 2345 0731

The encoded message is ready to be sent to the intended recipient. You now have a message that
can absolutely not be cracked by anyone but the intended recipient.

Decoding the message...

To decode a message, simply reverse the calculations. Subtract the key from the ciphertext using
Fibonicci subtraction. This means we allow no negative numbers. We add 10 if required. For
example, 1 - 9 would yield 2 (because we add 10 so that we're able to subtract 9 from 11). The
first block in the ciphertext tells our intended recipient where to start in the key. Here's what the
recipient's working sheet looks like.

Ciphertext 0919 0626 2521 2345 0731

Key           0919 0523 2226 1725 0811

Plaintext       -- 0103 0305 1620 0920

Here's how we subtract 0523 from 0626.
The first column is 0 - 0 = 0.
The second column is 6 - 5 = 1.
The third column is 2 - 2 = 0.
The fourth column is 6 - 3 = 3.
(If your substraction look something like this: 1 - 6, it gives 1-6 = 5 because 11 - 6 = 5.)

By using the conversion tablet described earlier, the recipient converts the string of numbers
back into alphabet characters. In this example, 01=A and 03=C, so the first block 0103 converts
to AC. The string 0103 0305 1620 0920 becomes AC CE PT IT. The receiver reformats it to
become ACCEPT IT.

Security measures...

If your key is kept to yourself and the intended recipient, and no one else ever gets access to it,
this system is 100% secure. No one will ever break the code. Period.

But you need to be careful about security. Strong key security...means you must conceal your
key in a location where you'll know if it's been tampered with. Usually this means carrying it on
yourself at all times. Good disposal security...means shredding and/or burning your messages
and the keys when you are done with it. One time and one time only...means you don't use a key
more than once. Ever.

When used correctly, this system will enable you to share even the most sensitive pieces of
information with your colleagues over unsecured channels of communications such as mail,
email and even by phone.

Test your skills... To verify your new skills, try to decode the cyphertext by using the key below.

the key: 0418 4678 1223 4104 0804 0123 6212 8840 7013

the ciphertext:4104 1129 1028 6520 8360 8338

Remember that the first four-digit group in the ciphertext is a pointer indicating where to begin
in the key.

Max Penn

This article was posted on January 28, 2005