𝐂𝐨𝐝𝐞𝐬 𝐚𝐧𝐝 𝐂𝐢𝐩𝐡𝐞𝐫𝐬

𝐑𝐚𝐢𝐥 𝐅𝐞𝐧𝐜𝐞 𝐂𝐢𝐩𝐡𝐞𝐫

In rail fence, the plaintext is written diagonally on a successive rails of an imaginary fence. Move up if you reached the bottom rail then move down if you reached the top rail and so on, until all the plaintext was written.
It depends on how many rails you're going to use.

For my example, I'll use 3 rails
Plaintext: ice district

i . . . i . . . i
. c . d . s . r . c
. . e . . . t . . . t

-The ciphertext is read off in rows

Ciphertext: IIICDSRCETT

This time, I'll use 4 rails

i . . . . . t
. c . . . s . r
. . e . i . . . i . t
. . . d . . . . . c

Ciphertext: ITCSREIICDT

~~~CTTRO