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.