How to Encrypt a Rail Fence Cipher
Write down your PLAINTEXT message on a piece of paper.
Then write each letter of the plaintext on two separate lines - the first letter goes on the first line, the second on the second line, the third letter goes back on the first line, and so on.
Count the total number of letters used.
The total number of letters should equal a multiple of 4 (8, 12, 16, 20). If not, you will need to add extra letters, called NULLS, until it is a multiple of 4.
Beginning with Line 1, combine the letters from both lines to create your CIPHERTEXT.
Divide the letters into as many groups as you like.
CONGRATULATIONS! You have successfully created a RAIL FENCE CIPHER!
How to Decrypt a Rail Fence Cipher
Divide the letters in half by drawing a line through the ciphertext.
Write the first half of the message on one line and the second half on a new line beneath it. Make sure you leave a space between each letter.
Rewrite the message by combining letters from Line 1 and Line 2.
Make sure that you alternate between lines and leave out any NULLS that are included at the end.
CONGRATULATIONS! You have successfully deciphered a RAIL FENCE CIPHER!