CIPHERS

The key is a book or other piece of text. The code is a series of numbers representing some or all of the following; a page, paragraph, sentence, line, word, and letter.  

Fun Fact: 

In an episode of Criminal Minds “The Fisher King,” a book cipher was brought to the Behavioral Analysis Unit by the UNSUB via Agent Hotchner's wife. The cipher was part of a larger puzzle.

Tips: 

• To crack a book cipher, you will need to locate the key.  Watch for mentions of favorite books, brochures, flyers, and sometimes just a simple quote can be used as a key.   

• Look for a series of numbers separated by commas or periods.  Check your evidence, and look for any reference to online brochures or books.   

• The sequence can vary, and you may need to try a few variations before you start to see the intended message.

A cryptogram is a substation cipher, where each letter is replaced by a different letter, number, or symbol. 

Fun Fact: 

Cryptograms were initially used to encrypt military secrets and can now be found in word puzzle books. They were first used for entertainment purposes in the Middle Ages by monks who had spare time for intellectual games.

Tips: 

• Scan through the cipher, looking for single-letter words.  They are almost definitely A or I.

• Count common symbols.  The most common letters used in the English language are E, T, A, O, N, I, and S. These letters might get repeated in many of the words in a sentence. 

• Look at your two-letter words following the above strategies and, using deduction, patterns should begin.​

Morse code is an alphabet or code in which letters are represented by combinations of long and short signals of light or sound.

Fun Fact: 

The Morse code, or CW, as it is often called, is still widely used by radio amateurs where it is still able to provide a very effective mode of communication.

Tips: 

• This cipher is not always used with sound or light.  It can be written using dots and dashes.   The dots and dashes can also be replaced with other symbols, letters, and numbers.  

• Look for patterns that are in twos.  Two different kinds of flowers could equal a dot and a dash.  

The Polybius Square is a five-by-five grid filled with a single letter in each square and combining two letters, traditionally I and J. It is also possible to combine other pairs, such as V and U.

Variations: 

1. Another alternative is to include the digits 0-9, 

2. The order of the alphabet does not always go left to right or top to bottom.  It may also be placed diagonally, and to make it even harder to crack the alphabet could be placed rotating diagonal.

3. The coded message can be numbers, letters, or even symbols.   

Fun Fact:

One of the first recorded incidents of cryptography occurred in Ancient Rome. A Greek soldier and historian named Polybius created a cipher called the Polybius cipher or more commonly known as the Polybius square. Ultimately, this cipher became an essential tool for the Roman Empire, as it gave the Romans a serious advantage over their enemies.

Tips: 

1. To spot this type of cipher, look for groupings of two letters or numbers.  

2. Keep your eye open for a square that could be used for decoding as well as five-letter words written in two different directions. 

A null cipher, also known as concealment cipher, is an ancient form of encryption where the plaintext is mixed with a large amount of non-cipher material.

Fun Fact: 

A famous example of a null cipher is one sent by a German Spy in WWII. The message read: Apparently, neutral’s protest is thoroughly discounted and ignored. Isman hard hit. Blockade affects pretext for embargo on by-products, ejecting suets and, vegetable oils. 

Taking the second letter in each word, the following message emerges: 

Pershing sails from NY on June 1 

Tips: 

1. The hidden message can be anywhere in the text from the first letter of every line or sentence to the last letter of the line.  

1. If a message or text seems to not make complete sense when reading it, scan the text for other ways to read it. 

2. ​

.

When decoding a caesar, each letter is replaced by another letter with some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on. Shift ciphers are a more general form of the Caesar cipher. The Caesar cipher is meant to be a right shift by three. In a general shift cipher, any shift amount can be used.

Fun Fact: 

The Caesar cipher is one of the earliest known ciphers. It is named for Julius Caesar, who used it to encrypt messages of military importance that he did not wish to fall into enemy hands. His nephew, Augustus, used a modified version of the cipher for similar purposes and it is the basis for later ciphers such as the Vigenère cipher.

Tips: 

Watch for numbers in your mystery that could tell you how many times to shift the message. 

The Atbash cipher is a substitution cipher with a specific key where the alphabet letters are reversed. All 'A's are replaced with 'Z's, all 'B's are replaced with 'Y's, and so on. It was initially used for the Hebrew alphabet but can be used for any alphabet.  

Fun Fact: 

Atbash Cipher is a simple monoalphabetic substitution cipher used to encrypt the Hebrew alphabet. Supposedly, the Book of Jeremiah has several words enciphered through the use of Atbash.

1. Choose the keyword: In this case, our keyword is "ZEBRA."

2. Remove duplicate letters: Remove any duplicate letters from the keyword. In our example, "ZEBRA" remains as "ZEBRA" since there are no duplicate letters.

3. Create the keyword-based alphabet: Write down the unique letters from the keyword in order, followed by the remaining letters of the alphabet not used in the keyword. 

4. Encrypting a message: To encrypt a message using the keyword cipher, replace each letter in the message with the corresponding letter from the keyword-based alphabet. For example, if you want to encrypt the word "HELLO," you would replace:

5. "H" with "Z" (from the keyword)

6. "E" with "E" (from the keyword)

7. "L" with "R" (from the keyword)

8. "O" with "T" (from the keyword)

9. So, "HELLO" encrypted with the keyword "ZEBRA" becomes "ZERTT.