Rail Fence Cipher Explained
The rail fence cipher reorders letters along zigzag rails; letter identities stay the same. Encrypt on Cipher Portal with rails 2–100, or open the rail fence decoder guide.
What is a rail fence cipher?
Imagine writing plaintext in a sine-wave pattern across horizontal rails, then reading row by row. That permutation hides words without changing letter frequencies—ciphertext has the same multiset of letters as plaintext.
Scouts, puzzle hunts, and transposition lessons use Rail Fence because it is easy to diagram on paper.
How Rail Fence encryption works
The key is an integer rail count (commonly 2–5 in puzzles). Cipher Portal prompts for rails on encrypt and decrypt. Decryption inverts the rail walk using the same count.
Key recovery can try plausible rail values and rank readability—available on decrypt with empty key where supported.
Transposition vs substitution
Substitution ciphers change symbols; Rail Fence only shuffles order. Frequency analysis behaves differently: letter counts match plaintext, but bigrams look scrambled. Compare substitution and rail fence examples.
Frequently asked questions
What is a rail fence cipher?
A transposition cipher that writes text in a zigzag across rails and reads rows sequentially.
What is the Rail Fence key?
The number of rails (rows) in the zigzag, typically an integer from 2 upward.
Does Rail Fence change letter frequencies?
No—only order changes; single-letter histograms match plaintext.
How do I use Rail Fence online?
Select Rail Fence on Cipher Portal, enter text and rail count, encrypt or decrypt.