The irony of history is that the technology designed to protect money from the state was born from technologies the state used for total war.
💣 Picture September 1939. Germany invades Poland, and two days later, on September 4, Alan Turing reports for duty at the Government Code and Cypher School in Bletchley Park. But the real action happened a month and a half earlier. On July 25, 1939, Poland’s Biuro Szyfrów revealed its Enigma-cracking methods to the British and French—including a device called the "bomba," an electromechanical beast designed to brute-force the settings of the German cipher machine. Polish cryptographers like Marian Rejewski had been reading German intercepts for six and a half years, but when the number of rotors increased from 3 to 5 (with 3 selected from 5), the cracking difficulty jumped tenfold. It wasn’t a qualitative problem—it was a quantitative one, demanding tons of paper.
📊 The key tool? Punched sheets—60 series of 26 sheets each. This was a brute-force attack, but executed in the physical world. Every hole in a sheet corresponded to a potential rotor setting. By layering sheets and backlighting them, cryptographers hunted for "matches"—gaps that pointed to a possible key. The work was hellish, requiring more staff and massive volumes of manual labor. The irony? The future of decentralized money, which rejects centralized control, was born as centralized paper computations, vital to the Allies’ war effort.
🤯 Upon arriving at Bletchley Park, Turing made a critical observation about Kriegsmarine (German Navy) messages: their initial settings were encrypted on a shared Grundstellung (base rotor position), then superficially scrambled using bigram and trigram tables. This led to the creation of Banburismus—a cryptoanalytic process that foreshadowed modern probabilistic methods in cryptography. The process used sequential conditional probability analysis to extract information about likely Enigma machine settings.
⚖️ It spawned Turing’s invention of the "ban" as a measure of evidence weight in favor of a hypothesis. Imagine a "proof of work," but performed by the human brain and paper. Banburismus’s goal was to reduce the time needed by the electromechanical "Bomba" machines by identifying the most probable right and middle Enigma rotors. Hut 8 ran this procedure continuously for two years, stopping only in 1943 when enough machine time became available. It was optimization, resource minimization—a concept deeply embedded in Bitcoin mining economics.
💡 Banburismus was an evolution of the "clock method" invented by Polish cryptographer Jerzy Różycki. The gap between mechanical computation and human intuition began to close. Turing, in effect, created a protocol for "trusting" a probabilistic result without full enumeration—a concept that underpins blockchain transaction confirmation today, where not every node verifies every transaction from scratch but relies on the chain’s accumulated difficulty.
🛳️ The breakthrough came from luck and brute force. On April 26, 1940, the British destroyer HMS Griffin captured the German armed trawler Polaris in the North Sea, en route to Narvik. The Germans hadn’t managed to destroy all their cryptographic documents. The seized materials revealed the exact form of the indicator system, plugboard settings, and Grundstellung for April 23 and 24, along with an operator’s log that provided a long stretch of plaintext-ciphertext pairs for the 25th and 26th.
🗝️ Though the bigram tables themselves weren’t captured, Hut 8 used the settings lists to retrospectively read all Kriegsmarine traffic intercepted from April 22 to 27. This allowed them to partially reconstruct the bigram tables and attempt the first Banburismus attack on Kriegsmarine traffic starting April 30. The first day cracked (May 8, 1940) became "Foss Day," named after cryptanalyst Hugh Foss. The operation dragged on until November, the intelligence was stale, but it proved Banburismus worked.
🎰 This was literally a prototype of a "51% attack"—but for noble ends. With enough captured data (like computational power in a network), the Allies could impose their "version of truth"—decrypted messages. Later captures, like the "first Lofoten trophy" from the trawler Krebs on March 3, 1941, provided full keys and allowed the statistical scoring system to be refined. Banburismus became the standard procedure against naval Enigma until mid-1943. Bitcoin’s decentralized network defends against such attacks by making them economically unviable, but in the 1940s, attacking the network (the Kriegsmarine) meant physically seizing its "nodes" (ships) and stealing their "private keys" (codebooks).
🔮 While Turing worked on Banburismus, other geniuses at Bletchley Park grappled with even more complex systems. In 1942, Turing developed a manual code-breaking method called "Turingery" (or the "Turing Method") for cryptanalyzing the Lorenz cipher, used in German Geheimschreiber machines. The British called this non-Morse traffic "Fish," and this particular machine "Tunny." Reading a Tunny message required knowing the system’s logical structure, deducing the periodically changing pattern of active cams on the wheels, and setting the initial positions of the scrambler wheels for each message (the message key).
💻 William Tutte and his colleagues had deciphered Tunny’s logical structure by January 1942. Turingery was applied to the key stream (which could be obtained thanks to German operators’ mistakes—transmitting multiple messages with the same key, creating "depth") to deduce cam settings. This was a qualitative leap—analyzing not the cipher itself, but metadata and errors in its use. Meanwhile, from 1940 to 1941, Max Newman and his team, including Turing, built the top-secret computer "Heath Robinson," named after a cartoonist who drew fantastical machines.
⚡ The apex was "Colossus"—a vacuum-tube programmable cryptanalysis machine designed by Tommy Flowers and installed at Bletchley Park in January 1944. It was hundreds of times faster than Heath Robinson and could determine many Lorenz settings in hours instead of weeks. Colossus compared two data streams, counting matches based on a programmable Boolean function. One stream was the encrypted message, read from a paper tape at high speed. The other was generated internally by an electronic simulation of the Lorenz machine at various trial settings. If the match count exceeded a threshold, the result was printed on an electric typewriter. This was a giant step toward the idea of verifiable computations performed by a machine more trustworthy than a human—the cornerstone of trust in blockchain-like protocols.
📌 Today, looking at consensus algorithms and SHA-256 hashes, it’s worth remembering the punched sheets of Polish cryptographers and Turing’s "bans." Modern cryptography is a direct descendant of that arms race, where trust in the system wasn’t ensured by central authority but by mathematical verifiability and distributed work. Bletchley Park didn’t invent Bitcoin, but it built the intellectual foundation on which Satoshi Nakamoto constructed his "peer-to-peer electronic cash system." The irony? Tools created to save centralized states ultimately gave rise to a technology that seeks to make those states optional.