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rail fence · zigzag transposition · configurable rails · live

Encode with the Rail Fence cipher

Write the text down and up across N rails, then read it off row by row. Classic transposition cipher with a configurable rail count. Runs locally in your browser.

Rail Fence Cipher
Input
25 B
1 lines
Output
25 B
1 lines
Status
ready
live
Ratio
1.00×
out/in
input · text
output · rail fence
WECRLTEERDSOEEFEAOCAIVDEN
Quick Start

How to use the Rail Fence cipher

Characters are written diagonally onto rails — the writing head moves down to the bottom rail, then back up, in a zigzag. Reading the rails row-by-row produces the ciphertext.

  1. 01

    Choose rails

    2 through 10. More rails means a longer cycle and a more scrambled output.

    Bytes flow through TextEncoder/TextDecoder for predictable UTF-8 semantics — emoji, surrogate pairs, and combining marks all encode losslessly.

    railsUTF-8TextEncoderlosslesslive
    rails · raw bytes3 · UTF-8
    W . . . E . . . C . . . R . . .
. E . R . D . S . O . E . E . F .
    loaded · UTF-8MIME · ready
  2. 02

    Pick a mode

    Encrypt writes the zigzag and reads it off; decrypt inverts the process.

    Hash and signature operations call crypto.subtle from the Web Crypto API, so output matches OpenSSL / Node bit-for-bit.

    modeWeb Cryptosubtledeterministiclive
    mode · optionsencrypt · live
    encrypt | decrypt
    options applied · livelive
  3. 03

    Type or paste text

    Spaces, digits and punctuation are part of the zigzag — they end up shuffled.

    Options re-run instantly through useEffect + useMemo — switching URL-safe mode or padding doesn’t re-encode from scratch.

    inputmemoisedoptionsinstantreactive
    input · encodedtext · ready
    WEAREDISCOVERED...
    encoded · livelossless
  4. 04

    Copy or download

    One click to clipboard. Download as .txt.

    Copy uses the Async Clipboard API; downloads ship via Blob with the appropriate MIME (text/plain, image/png, …) so external tools recognise them.

    exportclipboardblobMIME-correctclient-side
    ok · copiedready · done
    Copied
    shipped · ready to shipsuccess
Pro tips

Encoding without surprises

Always UTF-8 first

Use TextEncoder / TextDecoder for bytes ↔ string conversion. btoa alone breaks on non-ASCII.

URL-safe vs standard Base64

Standard uses +, /, =; URL-safe swaps to -, _, no padding. Don’t mix them.

Hashes aren’t passwords

SHA-256 is fast; that’s good for fingerprints, bad for passwords. Use bcrypt / argon2 for credentials.

Watch padding rules

Some decoders are strict about = padding, others auto-pad. If round-trips fail at exactly 1 or 2 bytes, check padding.

Use Web Crypto for keys

Generate cryptographic keys via crypto.subtle, never Math.random. The latter is predictable.

JWT decode ≠ verify

Decoding a JWT just splits and base64-decodes. Verification needs the issuer’s public key / shared secret.

Related toolsCaesar CipherSubstitution CipherVigenere CipherPolybius SquareAtbash CipherBacon Cipher
Use Cases

When to use Rail Fence

Transposition demos, CTFs, escape rooms.

Transposition intro

Cleanest example of a transposition cipher for teaching. Output round-trips losslessly with the matching decoder — both run client-side, so end-to-end testing happens in a single tab. Encoding flows through TextEncoder for predictable UTF-8 semantics.

RFC-compliant

CTF puzzles

Often combined with substitution layers in mid-tier challenges. Web Crypto's subtle.digest produces output that matches OpenSSL, GPG, and Node's crypto module byte-for-byte. That makes the result trustworthy as a content fingerprint, ETag, or integrity check.

OpenSSL-matched

Escape rooms

Visual zigzag pattern translates well into physical puzzle props. Pairs cleanly with HMAC, JWT, and signed-URL workflows where bit-level correctness matters. The browser's crypto stack is FIPS 140-validated in Chrome and Firefox, so it's production-grade.

lossless

Brute force demo

Show that only N-1 rail counts are worth trying. Output uses canonical RFC 4648 / 7515 alphabets so curl, openssl, and any standards-compliant decoder accept it as input. URL-safe variants drop padding for tokens that travel in query strings.

byte-identical

Cross-implementation

Sanity-check Rail Fence code in other languages. Heavy hashing runs through useMemo so large inputs don't block typing. PBKDF2, bcrypt, and Argon2 expose configurable cost factors — tune for your threat model, not the default.

spec-grade

Hint hiding

Hide spoilers in walkthrough articles. Same input plus same options always yields identical bytes. That's the foundation for content-addressed storage (IPFS, Git, S3 ETags) and means the output is safe to commit to fixtures.

production-ready
FAQ

Frequently asked questions

It is the number of rows in the zigzag. With 2 rails the cipher is just every-other-letter; more rails create a longer cycle and stronger shuffle.
Switch to decrypt mode and use the same rail count. The tool reconstructs the zigzag positions and reads them out in order.
Yes — every character takes a slot in the zigzag, so they get shuffled too.
No. With only a handful of plausible rail counts, brute force is trivial.
No. The cipher runs locally in your browser.
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