JBO Catflap Cipher

The purpose of the Catflap Cipher is to secure text and messages using classical cryptographic methods. What all ciphers (except a One Time Pad) have in common is that ultimately, they are breakable. The issue is the amount of time it would take to break them and whether such time would be well spent. Some Modern methods of encryption rely on large numbers which (so Far) cannot be factored for security. Most traditional ciphers have a finite number of solutions ... consider a cipher system which uses an alphanumeric key (any sequence of alphanumeric and punctuation characters, and of any length) to perform polyalphabetic substitution of both upper and lower case letters, numbers, and commonly used punctuation, against a random table of cipher characters and you have the basis of the Catflap Cipher. The programme provides tabbed pages into which PlainText, or ciphertext, may be typed or loaded from suitable text files. Once a key has been entered, the user may encrypt or decrypt the desired text. As space characters are permitted in Catflap, it is possible for small sequences of spaces to appear in the cipher text. For this reason the user should avoid using `copy and paste` for transferring the ciphertext from the Catflap programme to its destination. It is recommended to save the ciphertext and then transfer the resulting file to the recipient by the intended means, perhaps attached to an email. Alternatively, the ciphertext can be printed directly from Catflap. For amounts of text of one kilobyte or more, the distribution is usually below 6% for all characters (assuming a key which is not very repetitious). It is possible to use randomly generated keys equal in length to the plaintext, thus enabling Catflap to operate as a One Time Pad cipher. Even with shorter and more user-friendly keys, patterns in ciphertext are not helpful to anyone attempting to analyse the cipher.