Crypto-Crypt: Codes and Ciphers

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Caesar Cipher:

The Caesar Cipher is so called because it is believed that Caesar and his armies used it to communicate top secret messages. In fact it is a very easy cipher to break.

To implement the Caesar Cipher, you must simply take each letter of your message and shift it forwards through the alphabet a set number of places. If you go past the end letter, you continue from the beginning of the alphabet.

For example: THIS IS THE MESSAGE is enciphered to VJKU KU VJG OGUUCIG.

The shift in this case is two places, so T is shifted two places forward to V, H becomes J and so on.

To decipher the message, the receiver must know the number of places the message was shifted. This is known as the key. The key for this message is 2. Now the receiver can shift each letter of the message backwards two places, or forwards 24 places, as there are 26 letters in the alphabet and 26 - 2 = 24.

The Caesar Cipher is weak because, there are only 26 different shifts to choose from (in English), so a potential attacker only has to try a maximum of 25 different shifts of a part of the message to arrive at the answer. This can be done by hand inside of fifteen minutes.

For example:

An interceptor wants to decipher the message: IAAPWPIEZJECDPXUPDAXNEZCA, but he does not know the key.

He must advance each letter in the message by one and write the new message underneath.

IAAPWPIEZJECDPXUPDAXNEZCA

JBBQXQJFAKFDEQYVQEBYOFADB

If he continues this, he will eventually discover the message:

KCCRYRKGBLGEFRZWRFCZPGBEC

LDDSZSLHCMHFGSAXSGDAQHCFD

MEETATMIDNIGHTBYTHEBRIDGE

The interceptor has cracked the message with very little effort. It took him four shifts to find the message, so the original key used to encipher the message was (26 - 4) = 22.

Monoalphabetic Substitution Cipher:

Information on this cipher and more coming soon...

Glossary:

These words and more will be explained soon!

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Stenography