Columnar Transposition Cipher
Enter text and an ASCII-letter key. Text is written row-wise, then read by columns in alphabetical key order.
A QUICK WALKTHROUGH
How to use this tool
- Enter text and a nonempty key containing ASCII letters only.
- Choose Encrypt or Decrypt.
- Run the local conversion and review the result.
Key ordering and duplicate letters
Columns are read in ascending A–Z key order. If a key repeats a letter, repeated columns keep their original left-to-right order. The final row is ragged and is handled without padding.
Character preservation
The tool transposes Unicode code points as entered, including spaces, punctuation, digits, accents, and emoji. The key itself must contain ASCII letters A–Z or a–z.
Educational use only
This is a historical transposition cipher for learning and compatibility. It is not secure cryptography and should not protect passwords, secrets, or sensitive data. Processing stays in this browser.
GOOD TO KNOW
Common questions
Does the tool add padding?
No. The final row is ragged, so encryption and decryption preserve the exact input length.
How are duplicate key letters handled?
They are ordered from left to right, which makes the column order deterministic.
Is this secure encryption?
No. Columnar transposition is a classical educational cipher, not modern cryptography.