Route transposition — Letters fill a grid and are read out along a path — spiral, boustrophedon, diagonal — rather than straight down the columns.
Plaintext filled into a grid, read out along a fixed route.
A worked example§
Encrypting a sample with the cipher itself, at build time:
MEET ME BY THE OLD CLOCK TOWER AT DAWNKey: cols=5, route=spiral_out_cw
produces the ciphertext
MEETMHCTANWADTOLEEBYTDKREWOOLCThis 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§
The route and the width are the key, and there are not many plausible routes, so the search is small.
History and context§
The Union army's Route Cipher carried Lincoln's dispatches, mixing transposition with codewords for names and places.
See also§
Columnar transposition · Rail fence · Skip / scytale · 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 Route transposition broken?
The route and the width are the key, and there are not many plausible routes, so the search is small.
What key does the Route transposition use?
(columns, route). The keyspace is unbounded in practice.
How much ciphertext do I need?
At least 8 characters for this solver to attempt it; short messages can be readable and still not be proof.
Can I break a Route transposition on this page?
Not with the browser build, which targets the common puzzle families. The desktop version searches it: see the Windows app page.