We are starting to round the corner into the home stretch, with just a week left on the campaign. We continue making steady pace towards stretch goals, and I think we have a really good chance of hitting one when the end of campaign rush hits.
Real World History
Thanks to everybody who voted in our last preview poll. Real-world history was the clear winner. We have one more poll up for our final preview next week.
Real world history is always one of my favorite parts of writing these. It’s interesting to see how these simple technologies evolve (or sometimes stay the same for centuries). Plus it’s fun to see many tropes common in fantasy RPGs do or don’t line up with medieval history.
One of favorite things to see is a back and forth, where technologies respond to developments elsewhere. This is what happened with cryptography, as new cyphers emerged after people cracked the old ones.
A Brief History of Sending Secrets
Keeping secrets stretches back to the start of human history, but formal ways of communicating them—codes, cyphers, and steganography—are more recent inventions.
One of the first examples we know of are clay tablets from around 1500 BCE that show an encoded recipe for pottery glaze, the ancient world's trade secrets. Hebrew scholars have used substitution cyphers since at least 500 BCE.
While mercantile and religious secrets were important, the most common reason for passing hidden information is war. In his Histories, written around 440 BCE, Herodotus describes hiding a message about an upcoming attack on the wood backing underneath a reusable wax tablet. At some point in the 300s BCE, Aeneas Tacticus gave an even more thorough description of ways to send hidden messages in his text How to Survive a Siege. Many of those techniques, like invisible ink and marking letters in otherwise innocuous texts, continue to be used in modern times.
The Caesar Shift Substitution cyphers, replacing one letter of the alphabet with another, existed long before Julius Caesar. However, having once been emperor of most of the western world, his name became associated with this fundamental form of cryptography. In the Caesar shift you substitute one letter for another, always a set number of letters away from the original, just like popular decoder rings. It's said that Julius Caesar personally used a shift of three for his communications, so A became D, B became E and so forth.
Simple substitution cyphers like these remained common up through the Middle Ages, but these codes could all be easily broken, thanks to the code breaker's most powerful weapon . . .
The Frequency Table Frequency tables record how common each letter is in standard written communications for a given language. In English, E is the most common letter, so when looking at a simple substitution cypher, the most common character is likely to be E.
Al-Kindi, an Arabian mathematician, created the first frequency tables in his aptly named Manuscript on Deciphering Cryptographic Messages. For centuries these techniques were known only to the Arabic-speaking world, but the ideas moved to Europe by the time that continent had its Renaissance.
In response, cryptographers developed ways to thwart analysis, such as translating common letters to more than one symbol in the code and switching what symbols mean as the message proceeds, so the first letter might be encoded by the letter three steps away, but the next might be four steps, and then five steps. Though these codes were harder to break, none were impossible to crack, and the additional steps took more time and increased the error rates for the people sending and receiving the messages.
Keys and Automation The invention of the cypher key finally defeated the frequency table. Keys are simply algorithms used to encode information that include strings of randomly generated text. One of the first examples is the one-time pad, first described in 1882 and rediscovered and patented in 1917. These pads were simply papers with random letters that were used to determine what sort of Caesar shift to apply. With the advent of electronic cypher machines and later computers, these keys became ever increasingly complex.
Though the key became cryptographers’ greatest strength, it also became the main focus of attack, because if the decryptor could get their hands on the key, they could freely decode messages. Indeed, some of the first breakthroughs decoding the Enigma machine, used by German forces in World War Two came because lazy enigma machine operators set the key to settings like AAA or BBB.
Modern cryptography relies on long keys and computer algorithms to encrypt and decrypt data. The process has become so easily automated that it's used not only for trade secrets and military movements, but also everyday emails. While far more secure than codes of the past, the ever-increasing speed of computers also increases the ability to crack codes. Computers can use “brute force” to try every single possible key for codes that were “unbreakable” decades ago. Despite all that computing power, just as with the Enigma codes, humans are by far the weakest link in modern cryptography. It's far easier to trick a person into revealing their password than to decode their information on their hard drive.
