How to Encode and Decode Using the Vigènere Cipher

Step-by-Step Guide

1. 1

   Step 1: Obtain a Vigenère Square (see Sample) or create a Vigenère Square on your own.

   For this example we will use:
   LIME , For this example we will use:
   LIFEGUIDEHUB , Do this until you run out of message:
   LIFEGUIDEHUB LIMELIMELIMELIME , In the example used for this article, the word LIME fits perfectly but when the keyword is not a perfect fit, there is no need to use the full word.
   
   For example:
   LIFEGUIDEHUBOFTHEBEST LIMELIMELIMELIMELIMELIMEL , That's your cipher letter. , Using the sample Vigenère square given above, the first ciphertext letter is an H coming from row L and column W.
   
   So the ciphertext is:
   HQWMSWIMDBTIMMEX
2. 2

   Step 2: Think of a keyword that is shorter than the phrase or phrases you want to encipher.

3. 3

   Step 3: Write down your message without spaces.

4. 4

   Step 4: Write the keyword under your message

5. 5

   Step 5: carefully lining each letter up with a letter from your message.

6. 6

   Step 6: Cut the keyword to fit the phrase if needed.

7. 7

   Step 7: Go to the row of the first letter of the keyword in the Vigenère Square and go to the column of the first letter of the actual message and find the intersection point of the row and column.

8. 8

   Step 8: Continue on in this fashion until your entire phrase is ciphered.

Detailed Guide

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