Columnar transposition cipher
Columnar transposition writes the message in rows under a keyword and reads the columns out in the alphabetical order of the keyword's letters. Nothing is substituted; every character keeps its identity but moves. The last row may be incomplete (irregular columnar, no padding).
Break without the keyword
Paste ciphertext and the solver tries every column order up to seven columns, ranking each by how much the result looks like English. It reports a canonical keyword (ABC ranks) that you can paste into the form above. It works best on letters-only ciphertext: the position of spaces and punctuation carries no statistical signal.
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About the columnar transposition cipher
Transposition is the other half of classical cryptography: where substitution ciphers disguise the letters, transposition ciphers leave them alone and scramble their order. The keyword only fixes a column order — ZEBRAS means "read column 5 first, then 3, then 2…" — so the real key space is the number of ways to order the columns. That grows quickly, which is why armies used columnar transposition into the twentieth century, usually applied twice (double transposition) for serious traffic.
Its weakness is that the ciphertext keeps English letter frequencies exactly — an index of coincidence at English levels with unreadable text is the transposition signature thecipher identifier looks for. Short keys fall to trying every order, as the solver above does; longer keys fall to anagramming columns whose bigrams glue together well.