Aim
The goal is to design a cipher.
How it works
The ciphertext needs to carry clear character-level meaning, which means it should be built from at least the 26 letters of the English alphabet. The letters should follow the occurrence frequencies of a chosen dictionary. For each letter, the actual frequency can either match the reference or deviate from it. Mark a deviation as 0 and a match as 1. This produces a 26-position number. That number can be turned into a keyword through Morse code, base conversion, or another transformation; it can also be decomposed one-way to derive a key. Once the keyword is known, the plaintext can be recovered.
Two things are central: letter frequency and the method used to interpret the 26-position key. If the plaintext is fixed, both sides need a shared frequency reference to generate and compare ciphertext. Suppose they assume uniform frequency and use a digit to stand for repeated letters. Then a ciphertext such as
cefgjklmnoqsuvwxz4
corresponds to a key formed from possible combinations of the missing letters. A candidate interpretation can be tested by whether it produces something meaningful.
If the interpretation space is too broad, the keyword can be made to point to the source of the frequency reference. In that case only people who share the same reference—usually acquaintances—can decrypt the material. Privacy becomes a function of how close that relationship is. Someone who sees the message without that shared context has no clear way in. The method implicitly relies on the notion that the same coincidence will not occur twice; it can also be rebuilt to require several coincidences.
The scheme calls for a software package that generates ciphertext and handles decryption, and that package would need to be distributed to the intended users. The alphabet does not have to stop at 26 letters. A more complex version could use specified Chinese character frequencies or another reference to create a higher-dimensional coincidence. It does not need to be elaborate; it only needs to be complex for anyone other than the sender and receiver.