What is it and Why is it Important?
Coded writing has long been used to disguise messages and make them unreadable for people that don't know how to decipher them. A Cipher is used first to change a word or sentence into something that looks like gibberish or is unreadable called the "ciphertext". Another cipher is then used by another person to change the ciphertext back into a readable sentence which is called "Deciphering". As you will see but reading this article breaking a code is very much dependent on discovering the "key-word" which hold the answer to some of the more complicated codes. Some codes can be broken without the cipher or key-word.
Codes are most often used by the military to transfer messages. If the enemy doesn't not have the specific cipher they may not be able to "crack the code". Some of the most famous examples of coded writing were by Julius Caesar who used a very simple method of changing each letter in his message to the letter three places behind it in the alphabet. Another highly effective code was used by the Germans during WWII that was never cracked until the allies captured a cipher called the enigma device from a U-Boat. The most basic and oldest codes are those of dead languages that use symbols to depict words. Some are obvious and some are not which is why the Rosetta Stone was such a wonderful find since it translated two dead languages into Ancient Greek which was then easily translated.
Common Types
Substitution Cipher - Substitution ciphers are the easiest to make and encode but also the easiest to break but were widely used for a very long time to great effectiveness.
The make a substitution cipher one lays out an alphabet unchanged from A-Z. This is the "plaintext". A second alphabet is then laid out which is the ciphertext in a random order or any order of your choosing designating a random letter to be substituted for a letter in the standard alphabet. The code is they written using the cipher text. The person receiving the code would have to have the cipher specific text arrangement in order to decipher the message.
The problem with this method is that it can be cracked without the cipher text by finding the most repeated letter. Since the letter E is the most common letter in the English language its most likely that letter is E. This rational is further used for T then A and so on.
Vigenère Cipher - This type of cipher is a substitution cipher which uses two plaintext alphabets as a row and column then 26 alphabets that are added each shifted by one letter and laid out in a grid pattern. This system also uses a "key-word" in order to encipher and decipher the message. This was the system used by the Germans in WWII but they inputted the key word into a device which would then type out the deciphered code. The German Enigma device would also randomly switch key- words. The person deciphering the code needs the ciphertext and the key word.
The key-word will use the first column and the ciphertext will use the first row. Picking a key-word such as LEMON and using a phrase such as ATTACKATDAWN will mean that the key-word will be repeated for example LEMONLEMONLE. To encipher go to the first column to the L position, then use the top row and go the the A position for the message. The letter that intersects the two is L. This is the first letter of the ciphertext. After matching the key word with the message the ciphertext will look like this: LXFOPVEFRNHR. Deciphering is done the opposite way using the first letter of the ciphertext and the first letter of the key-word.
Pigpen Cipher - A pigpen cipher is also called a masonic cipher. Its a substitution cipher that uses symbols that are in place of letters. The letters are laid out in two "tic-tac-toe" grids and two Xs.
The resulting symbols will be representative of the spaces that the letters occupy. For instance the letter I will be a simple box, the letter J will be a box with a dot at the bottom and so on. It's sometimes called a masonic cipher because the Freemasons and the Rosicrucions enjoyed using it for coded messages. One of the most famous people that used it was George Washington.
Breaking the code is done the same way as the simple substitution cipher where you would find the most repeated symbol which would most likely represent the letter E.
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| Letter frequency for use in substitution codes |
Modern Day Cryptography
Modern day codes and ciphers are extremely complicated and are based on mathematical formulas. The one used today by banks and credit card companies is called public/private key cryptography. This type uses two "key numbers", one known to the person (public) and one known to the institution such as a bank (private). The message is encrypted using the public key and then decrypted with the private key. The ciphertext is a number so large that it is computationally impossible to break which makes it so secure. The ciphertext number could have over 100 numbers. If there is a question about the security of the transmission being decoded or deciphered more numbers can be added to the ciphertext, in theory to an infinite number.
Unsolved Coded Messages
There are several messages that exist that despite much effort have still not been cracked. Some are very old which have to do with languages such as the much talked about Voynich Manuscript.
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| "Voynich manuscript example" |
Another famous one is called Kryptos which is a sculpture that stands in front of the Headquarters of the CIA in Langley, Virginia. It was created by sculptor Jim Sanborn and contains four blocks of ciphertext and an attached Vigenère Cipher. The sculptor will not give a clue to what the answer will reveal but its considered to be a specific location. Three of the four blocks of the ciphertext have been deciphered which do suggest a location but only 150 feet from the sculpture itself. Sanborn says that each block is a riddle in and of itself which all must be solved in order to understand the final riddle. For further reading into Kryptos and the messages that have been decoded so far go here.
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| "Kryptos sculptor" by Jim Sanborn |
Deception is everywhere - Jim Sanborn
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