Myszkowski Transposition Cipher

How it is calculated

Only the letters A-Z of the keyword are used, in capitals. Each distinct letter gets a number by alphabetical order, and repeated letters share one number. All spaces are removed from the message and the rest (letters, digits, punctuation, case) is written into a grid, row by row, with as many columns as the keyword has letters; the last row may be short.

The ciphertext is read number by number, starting from 1. If a number belongs to one column, that column is read from top to bottom. If several columns share a number, they are read together row by row, left to right. Decoding rebuilds the same grid shape from the ciphertext length and fills it back in the same order. No padding is added, and the output has no spaces, so you should regroup it yourself if you want blocks of five. The result shows the key length and the mode used.

Common mistakes

• Expecting ciphertext in groups of five or with spaces. The result is one continuous string, and spaces in the message are removed before encryption, so the decoded text also has no spaces.
• Using a keyword with no repeated letter and expecting Myszkowski behaviour. Then every letter has its own number and the result is an ordinary columnar transposition.
• Typing digits or symbols in the keyword. Only letters count, so "to mato!" is the same key as TOMATO, and a keyword with no letters gives no result.
• Decoding with a different keyword, or after editing the ciphertext. The grid shape depends on the key length and the exact text length, so one lost letter breaks the decoding.
• Treating it as secure. It only reorders letters, so letter frequencies stay unchanged; use it for puzzles and learning, not for protecting information.