Ghostwriter System


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"Ghostwriter" is the common / non-technical name for the networks of electro-mechanical rotory cypher machines, as well as their associated codes and shorthand writing system, used by the United States of the Napoleon's Legacy Universe to compile, send, encypher & decypher coded messages.

Different versions are in use by different branches of the U.S. Armed Forces. Each Branch has its own models / forms of Ghostwriters that encode along different patterns, but they are all basically the same machines and are cross-compatible through special intermediate adapters. Additional versions of the devices are in use by the American Government.

Ghosthand
The associated shorthand writing method used to construct messages for the Ghostwriter networks is informally called "Ghosthand". It is derived from an alphabet-based shorthand introduced in 1952, commonly used by American courtroom stenogprahers, called "Forkner Shorthand" - named after its creator. Thus, in its written form, Ghosthand script is cursive and mostly phonetic - words are formed with a reduced number of letters in very succinct strokes according to how they sound rather than how they are spelled, with small marks to represent vowels (although vowels are often ommitted entirely when they are not phonetically necessary). Thus, "easy" becomes "e-z" and "paper" becomes "p'pr". Most forms of punctuation are either dropped or replaced with more symbols (i.e. a sentence break is shown with a check-mark and a paragraph break with two lines). Many word prefixes are reduced to capital letters (the prefix trans- becomes simply 'T', for example). Additional symbols are used to take the place of most particles and prepositions, but said symbols indicate the grammatical functions of these words rather than the words themselves. For example:

ev g'v - prs ' big f,t, ~ bIc r's

Eve gave the press a big photo of the bike race

The symbols between the words take the place of other words which are important to the grammar of the sentence, by indicating the grammatical functions those words would perform (rather than being direct replacements for them) - i.e. the various symbols can represent more than one word, depending on context, because different words which could be used in a particular situation often all have the same basic meanings. In the example sentence above, a dash replaces 'the' in the role of indicating a verb-object relationship, while the ~ replaces 'of' in showing possession.

On the Ghostwriter machines, the keyboards are stenotypes; they have fewer than the normal number of keys, and these keys are chorded (i.e. combinations of keys can be pressed in tandem to produce additional characters). This allows messages to be typed extremely quickly - as the shorthand writing requires fewer characters and there are fewer keys that the operator's hands have to move between - while also adding an additional layer of security in addition to / irrespective of the cypher machines themselves.

Ghostwriter Cypher Machine Design
To properly use a Ghostwriter keyboard, the operator must "re-learn" how to type. Not only are there fewer keys compared to a simple typewriter, but their positions are entirely different (the Ghosthand 'alphabet', if you will, is not in the same order as the English alphabet). Therefore, even if someone manages to decode the encryption, he or she cannot simply interprit the results as if the message were compiled in the English alphabet (i.e. '1' in a decoded message does not represent 'a'). No enemy Intelligence operator, as far as the U.S. is aware, has ever managed to figure out the Ghostwriter code system. Not only do the keys of the machines not corrispond to the format of the English alphabet, they are blank; operators type entirely from muscle memory.

The primary component of a Ghostwriter system, the actual cypher machine, is called the "Electric Code Machine Mark V". This is the original version, used by the U.S. Army. The Mark V is the primary subject of this article, as the other machines are derived from it and are essentially the same.

The ECM Mark V is a rotary cypher machine employing 12 wheels. Six of these, called the "main rotors", are normal electrical rotors with wiring contacts for all of the needed letters / symbols (i.e. the Ghostwriter alphabet) on either side. The contacts of each main rotor are scramble-wired in a different way; thus, there are six distinct types of rotors (labeled 'I.' through 'VI.') that cannot be used interchangably and must be put in the machine in a certain place for them to work.

Five of the other rotors, which alternate with the six main rotors, serve as "drive wheels" - these have mechanical spring-loaded pistons and cams that control / scramble the movements of the six main rotors. They can be manually tuned by the operator to create different paths through which the electrical impulses are routed, resulting in an additional level of encryption. Standard practice is to reset the drive wheels to new positions between each message.

The 12th and final rotor, which is connected to the sixth main rotor in the final position on the chain, is called the "reversal rotor" or "reflector". Each pulse, before becoming part of the encrypted message, is 'paired' as it leaves the last main rotor by passing through the reflector's scramble-wired, pairwise cross-connected electrical contacts. In other words: the reflector receives each electrical current leaving the last main rotor and passes it back through the entire chain of rotors along a different route and in reverse, thereby converting each individual character into a pair. Thus, the operator might type 'a' and said 'a' impulse comes out of the last main rotor scrambled as '2'. This '2' pulse then enters the cross-connctions of the reversal rotor, is rerouted back through all of the encoding rotors backwards, and finally comes out of the machine as '2Q' or somesuch.

Each cyper machine is issued with a case of multiple reflectors with different wiring patterns (six different models, in the case of the ECM Mk V, labeled "A-F"). These can be changed out before sending a message to further scramble it (but only one reflector, of course, is in the machine at any given time).

Main Rotors
The main rotors form the heart of a Ghostwriter cypher machine. Each such rotor is a disc approximately 10 cm (3.9 in) in diameter made from hard plastic and rubber with brass spring-loaded pins on one face arranged in a circle; on the other side are a corresponding number of circular electrical contacts. The pins and contacts represent the Ghosthand alphabet. Each pin is mated to a random contact on the opposite side by a wire running through the inside of the rotor, forming a complex pattern of connections that are never simply lateral. Thus, when the rotors are mounted side-by-side on the spindle inside the machine and ready for use, the pins of one rotor rest against the contacts of the neighbouring rotor to form an electrical connection.

The different types of main rotors in the chain (I., II., III., etc.) each have a different wiring arrangement and thus a different pin-contact connection pattern, but all rotors of the same type (i.e. all 'I.' rotors) are, of course, identical. Each main rotor type also has a different number of notches (though this has no relation to their labels - rotor 'I.' has three notches but rotor 'II.' has one, for example). These notches control / vary the stepping of the rotors, further scrambling the pattern set by the drive wheels (which are also used to vary the stepping / rotation of the main rotors connected to them, as described above). However, if more than one main rotor of the same type is accidentially used, or if the rotors are not arranged in the same order, then two given Ghostwriter machines will not be able to communicate with one another.

By itself, any single main rotor performs only a very basic type of encryption - a simple substitution cypher. For example, the pin corresponding to the letter 'E' might be wired to the contact for letter 'T' on the opposite face, and so on. The machine's security comes from using several such rotors in series and from the different controllable randomization features, all of which combine to create a complex poly-alphabetic substitution cypher.

Operation
Each rotor has an 'indentifier ring' around it with labels corrisponding to the positions of each of its pin-contact pairs. Main rotors are labeled using letters of the English alphabet, drive wheels with Arabic numbers and the reflector rotor with Roman Numerals. The external housing that covers the rotor assembly has twelve small glass 'ports' so that, when it is closed, the operator can see one row of the labels: these represent the rotational positions of the rotors. Protruding finger-wheels are built into the cover, with one connecting to each rotor, so that the positions of the rotors can be changed (i.e. turning a particular finger-wheel once will move its connected rotor so that label 'B' is seen through the glass port rather than 'A'). A master wheel which rotates the axle - and thus the entire rotor assembly together - is located on the side of the machine

The Ghostwriter cypher machines are issued with a complex set of operating documents, codebooks, etc. There are, in total, 100 different pre-established sets of positional arrangements for the main rotors, i.e. 'C-D-G-B-F-A'. The Orders of the Day will state the order in which the main rotors are to be arranged along the axle, which of these 100 sets should be used, which model of the reflector to insert for that day and which position said reflector is to be set in. It will also provide a daily table for rotating the master wheel - which has 12 possible positions, labeled with Arabic numerals - to a new setting at the top of every hour. So the master wheel should be rotated into the position designated for the first hour before the operator configures the rotors in that day's proscribed setting, so as to avoid confusion or mistakes.

Operators can vary the positions of the drive wheels at their own discretion, and will do so between each message except in special circumstances. This is because every Ghostwriter set includes a small electro-mechanical computer module that acts as an intermediary between the cypher machine itself and the radio it communicates through (i.e. the cypher is connected to the computer, the computer is connected to the radio). When a transmission from another Ghostwriter enters the computer from the radio, the computer is able to determine the configuration of said sending machine's drive wheels (as different settings on the drive wheels produce microscopically different gaps between the electric pulses comprising the message). The operator of the receiving cypher must configure his own drive wheels to match the setting indicated by the computer - so that it aligns with the sending machine - before routing the message from the computer to his own machine for decryption.