Comes with 2 tap code ciphers blocks for sender and receiver. Each block is 3x3x1/4" and fits both the hand and the pocket comfortably. All text is deeply laser engraved and brief instructions are lasered on the back. An encryption worksheet is also included which can be very helpful as you learn the code.The tap code, sometimes called the knock code, is a way to encode text messages on a letter-by-letter basis in a very simple way. The message is transmitted using a series of tap sounds, hence its name.The tap code has been commonly used by prisoners to communicate with each other. The method of communicating is usually by tapping either the metal bars, pipes or the walls inside a cell.Note that this system is not limited in usefulness to just tapping sounds. I could be used at night by flashlight code or in a field or ship to shore by flag waving or even ht in hand waving. The tap code is based on a Polybius square using a 5×5 grid of letters representing all the letters of the Latin alphabet, except for K, which is represented by C.Each letter is communicated by tapping two numbers, the first designating the row and the second (after a pause) designating the column. For example, to specify the letter "B", one taps once, pauses, and then taps twice. The listener only needs to discriminate the timing of the taps to isolate letters.The letter "X" is used to break up sentences, and "K" for acknowledgments.Because of the difficulty and length of time required for specifying a single letter, prisoners often devise abbreviations and acronyms for common items or phrases, such as "GN" for Good night, or "GBU" for God bless you.By comparison, Morse code is harder to send by tapping or banging because a single tap will fade out and thus has no discernible length. Morse code, however, requires the ability to create two distinguishable lengths (or types) of taps. To simulate Morse by tapping therefore requires either two different sounds (pitch, volume), or very precise timing, so that a dash within a character (e.g. the character N, ▄▄▄ ▄ ) remains distinguishable from a dot at the end of a character (e.g. E-E, ▄ ▄ ). Morse code also takes longer to learn. Learning the tap system simply requires one to know the alphabet and the short sequence "AFLQV" (the initial letter of each row), without memorising the entire grid. For example, if a person hears four knocks, they can think "A... F... L... Q". If after a pause there are three knocks, they think "Q... R... S" to arrive at the letter S.To view a video on this cipher, copy and paste this linkhttps://youtu.be/q4lI6_V6SqAMaterials: Wood
