Skip / scytale

From the Buttcrack Cipher Wiki — the free field guide to classical ciphers

Skip / scytale — Take every k-th letter, then every k-th starting from the next, and so on.

ct = pt[::k] + pt[1::k] + ... + pt[k-1::k]

A worked example§

Encrypting a sample with the cipher itself, at build time:

MEET ME BY THE OLD CLOCK TOWER AT DAWN

Key: 5

produces the ciphertext

MEELOTEBOOWDEYLCEATTDKRWMHCTAN

This example is generated by running the cipher when the page is built, and the round trip is checked, so it always matches what the solver does.

How it is broken§

One small unknown. Try every stride.

History and context§

The scytale of Sparta in modern clothing: a strip of leather wound round a baton of an agreed thickness, described by Plutarch.

See also§

Columnar transposition · Rail fence · Route transposition · Myszkowski transposition · AMSCO transposition

Browse every cipher in the Transposition ciphers family, read the history of codebreaking, or return to the wiki main page.

Frequently asked questions§

How is the Skip / scytale broken?

One small unknown. Try every stride.

What key does the Skip / scytale use?

stride. The keyspace is unbounded in practice.

How much ciphertext do I need?

At least 6 characters for this solver to attempt it; short messages can be readable and still not be proof.

Can I break a Skip / scytale on this page?

Not with the browser build, which targets the common puzzle families. The desktop version searches it: see the Windows app page.

The facts in this article are generated from buttcrack's cipher registry when the site is built, so they describe the implementation you can run on this page. Registry-generated content is checked against the code; the history is editorial.

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What this browser solver can—and cannot—do

It tries: Caesar, Atbash, ROT13, affine, Trithemius, rail fence, single-byte XOR, periodic Vigenère-family ciphers, autokey, selected encoding layers (such as Base64, hex, binary, decimal ASCII, Morse, and reverse), and—only with 60+ A–Z letters—statistical substitution.

It does not: prove a decryption, cover every classical cipher, or break modern encryption such as AES or RSA. Its ranking model is tuned for English, so a high score is a lead to verify with the method, key, and source context—not a guarantee.

Short text, non-English plaintext, non-Latin or symbol alphabets, missing keys, and unsupported formats can all leave no high-confidence answer. When that happens, the result includes input-specific observations and suggested next checks; those observations are not a claim to know the exact cause.

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