Iconic Machines

M-209

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    Volumes

    1. Vol 1 M-209 — Volume 1 — The M-209 — A Cipher Machine in a Lunchbox What the US Army's Converter M-209 was, how six pinwheels and a drum of 27 bars turned a hand crank into a cipher, who designed it, who built 140,000 of them, who broke it, and how to build one today — the orientation volume for the ten-part series
    2. Vol 2 M-209 — Volume 2 — Boris Hagelin — From AB Cryptograph to the C-38 An engineer from the Nobel oil fields, a failing Stockholm cipher company, a six-month race against the Enigma, a coin changer turned into a cipher machine, and the voyage from Genoa that put a Swedish design into the hands of the US Army
    3. Vol 3 M-209 — Volume 3 — How the M-209 Works — Pins, Lugs, the Drum and the Print Wheel Six key wheels and their 131 pins, the guide arms that read them, a drum of 27 bars that behaves like a gear with a variable number of teeth, a print wheel lettered backwards, and one letter followed all the way through the machine
    4. Vol 4 M-209 — Volume 4 — In the Field — Smith-Corona, Key Lists and Signal Procedure How a typewriter company turned a Swedish pocket cipher into a hundred thousand Army converters, what came in the canvas case, how key lists were written by shuffling cards, how a message was set up, sent and checked, and what the manual told an operator to do with a sledgehammer
    5. Vol 5 M-209 — Volume 5 — Breaking the Hagelin — German, Italian and Allied Attacks How German Army analysts read the US Army's field cipher from messages in depth, how Bletchley Park read the Italian Navy's Hagelin C-38m, what a 1950 Anglo-American conference decided the German success had been worth, and why three Bell Labs researchers left their own M-209 attack unpublished
    6. Vol 6 M-209 — Volume 6 — After the War — Crypto AG, the CX-52 and Operation Rubicon What became of the M-209 after 1945, how Boris Hagelin rebuilt his business in Switzerland around a pin-and-lug machine the Americans could not read, the friendship with William Friedman that turned into a secret agreement, and the half-century in which the CIA and the BND owned the firm and read the traffic of more than a hundred countries
    7. Vol 7 M-209 — Volume 7 — The Mathematics of Pins and Lugs — Period, Key Space and a Worked Encipherment Why six wheels repeat only after 101,405,850 letters, how a drum of 27 bars turns 64 patterns into 28 counts, how big the key really is, why the Army's key-list rules exist, and the manual's own message enciphered letter by letter on the manual's own key
    8. Vol 8 M-209 — Volume 8 — Building an M-209 — Design and Printing What open M-209 work already exists and why none of it is a printable machine; a design for a working mechanical replica built mainly from 3D-printed parts and stock steel — key wheels that grip 131 steel pins, a drum of 27 bars with sliding lug clips, a typewheel turned by kicked bars — and the materials, fasteners and printer settings to make it
    9. Vol 9 M-209 — Volume 9 — Building an M-209 — Assembly, Setting the Key and Testing Putting the replica together in an order that tests each assembly before the next one hides it; zeroizing it and setting the 1944 manual's own training key list; the 26-letter check; acceptance tests against the simulator; and how a periodic or a scattered garble points to the faulty pin or lug
    10. Vol 10 M-209 — Volume 10 — Using the M-209 — A Field Message, Sent and Broken A day's traffic on one key list sent in wartime procedure, two messages carelessly sent with the same indicator, and the German Army's own method for breaking them — a probable word dragged through the depth, the counts written in columns, the pins and lugs fitted, the wheels fixed from the indicator — run on the unit's simulator in a few seconds