Moving from the Industrial Age to the Information Age, let's make a quick stop off during World War II. By the early 1930s, the Axis powers were heavily relying on the Enigma machine to encode and send Morse-coded messages amongst themselves. The Enigma was a beast of a machine , for that time, and the Axis powers believed not that it was uncrackable, but that nobody in their right mind would spend the years necessary to crack the thing, especially as the encryption improved over time. They were wrong. The Enigma was a hell of an encryption device, but it was hampered by that most eternal of problems: Humans are goddamn idiots. Just about every breakthrough the Polish, then Italian, then British, then American cryptographers made was due to a sloppy slip-up from an Axis Enigma operator. The problem: Morse code, transmitted with wireless radios, could be fairly easily intercepted. So both sides made sure to encrypt the crap out of their messages. Of course, if you could crack the encryption... Starting out in 1932, a Polish mathematician named Marian Rejewski joined the Polish Cipher Bureau and began attempting to break down the Enigma's defenses. His first breakthrough? Discovering the order of the letter notches on the Enigma's rotors was not the same as on German typewriters, but actually in alphabetical order. He began creating a series of perforated sheets to nail down the cipher further, but the Axis powers made a key change in the operation of the rotors that rendered all his work useless. Womp. Next, Rejewski created what would be called the Polish bomba, or bomb--an electro-mechanical machine that relied on a few key weaknesses (like how a letter could not be substituted for itself) to narrow the possible keys from some kind of ridiculous number (Wikipedia says 10 trillion) to a manageable 17,576. Then Rejewski's bomba simply performed a brute force attack, trying every single one of those combinations until it stumbled on the right one. This machine was capable of cracking the code in about two hours. The Axis continued to improve the Enigma, and the Allied cryptographers continued to crack it, each time. A few years later, Alan Turing, a Brit widely known now as one of the fathers of computing, built on Rejewski's work by creating his own device, known as the Turing-Welchman bombe. The bombe was actually more like an homage to than a development of the bomba, relying on the elimination of impossible matches rather than the guessing of the correct match. It was a rousing success, and suddenly, the Allies found themselves able to read the Axis communication. It was one of the biggest victories in military espionage of all time. By the end of the war, just about no German communication could be issued without the Allies intercepting and decrypting it. The information wasn't always used effectively; suddenly buried by a flood of data, the Allied militaries weren't really sure how to suss out the good information from the irrelevant. The Americans, for example, weren't able to use the data they'd encrypted to avoid a brutal defeat at the hands of the Germans at the Battle of Kasserine pass in 1943--even though they'd encrypted messages that foreshadowed German tactics. Still, the decryption of German communications was a major factor in ending the war--Eisenhower called the cracking of the Enigma "decisive" to the Allied victory.