Redefence Cipher Encoder/Decoder

About this calculator

The Redefence cipher is a keyed variant of the classic rail-fence cipher. Plaintext letters are written in a zig-zag pattern down and up across N rails (rows), exactly as in a normal rail fence — but instead of reading the rows off in top-to-bottom order, a numeric key determines the order the rails are read in, adding an extra layer of scrambling beyond the basic zig-zag.

Like other rail-fence variants, it's a transposition cipher — it rearranges letters rather than substituting them — and offers only modest security by modern standards. It shows up mainly in cryptography education, puzzle hunts, and CTF (capture-the-flag) challenges as a step up from the plain rail fence, illustrating how adding a key to a simple transposition scheme increases the keyspace an attacker has to search.