Scytale

plain

order

cipher

↺ reversible — the same rod (and key) winds it back. Type to wind the strip.

A real scytale — the Spartan cipher rod. Wind a strip of parchment helically around the rod, write along its length, then unwind: the letters scramble. Only a rod of the same circumference re-aligns them. It is a columnar transposition — the letters are rearranged, never replaced.

Type to encipher

Mode

Circumference C — letters per turn (the rod's diameter, 2–12)

Keyword — its letters' alphabetical rank sets the column read-order

Column read-order (derived from the keyword)

Direction

The wrong rod — read the cipher at a different circumference

C′ = ≠ C → gibberish

Presets

Skin

Wound view (the strip on the rod) reads the plaintext along the helix; unwound reads the ciphertext straight down the rod, one letter per turn. Click the rod to toggle the view. Skins change only colour & material — never the geometry or the cipher.