Get Cracking: The Secret Codes & Ciphers Quiz

In World War II, the Nazis developed the Enigma code, which was meant to protect their messages from the Allies. For a long time, the code was seemingly unbreakable.

The Germans used the infamous Enigma machines, which look a lot like the typewriters of that era. These portable ciper machines had rotor scramblers, which kept the codes constantly changing, making it nearly impossible for the Allies to intercept and understand German messages before the solution became obsolete.

A ROT1 code simply rotates each letter one step through the alphabet. So "a" becomes "b" and "b" becomes "c," and so forth.

Not even close—ROT1 ciphers are considered by cryptographers to be child's play. They're still fun, but not much else.

Morse code is highly versatile and can be communicated through a sequence of short and long clicks, or taps, or flashes of light, or audio tones. People who get really good at Morse code can understand these signals instantly, without any equipment.

Morse was one of the men who invented the telegraph machine, an early communications device that relied on coded signals to relay messages. Those signals, of course, were Morse code.

Morse code is a type of monoalphabetic substitution. As with a Caesar shift or ROT1, it just means that a key is used to replace one letter of the alphabet with another symbol, whether it's a number or letter.

Jeremiah Denton was the Navy pilot who blinked a message in Morse code. His message? "Torture." It confirmed to U.S. officials that the North Vietnamese were mistreating POWs.

The most commonly used letter in English is "e." So, in the name of efficiency, Morse code denotes "e" with just one brief signal. Whenever you're trying to crack any code, it can help to keep in mind which letters and words are likely to be the most common.

There's no Trump method. Both the Koch and Farnsworth methods teach Morse code. Both methods rely on variations of repetition to help users develop speedy Morse code skills.

Pig Latin and Dog Latin are both language games that essentially mock real Latin, although the first is more widely known. It's not really much of a code or a secret, but that doesn't make it any less fun.

One example of steganography involves invisible ink, which is nearly impossible to see until the receiver exposes it to heat or another chemical trigger.

The Beale ciphers are a set of three ciphertexts from the 1800s that supposedly pinpoint the location of jewels and gold worth tens of millions of dollars. The gold was said to be hidden by a man named Thomas Beale in the 1820s, who apparently disappeared after hiding it.

In the 1880s, an unknown person published the codes in a paper, ostensibly for the purpose of finally solving the decades-old riddle. The codes immediately grabbed the public's attention.

Parts of the codes were indeed cracked after it was discovered that some of the numbers referred to the order of words in the Declaration of Independence. Part of the message revealed "I have deposited in the county of Bedford, about four miles from Buford's, in an excavation or vault, six feet below the surface of the ground, the following articles...." But there are still important elements missing from the puzzle, and nobody has reported finding the treasure. Some experts maintain the whole thing is a longstanding hoax.

The Voynich manuscript probably dates back to the 15th century. It's a confounding book filled with lines of mysterious text and whimsical drawings. Many think it's a secret code of some sort.

The best codebreakers have tried and failed to understand the Voynich manuscript. No one really knows what the mysterious book might mean. It might simply be a well-constructed hoax.

The Voynich manuscript might be something akin to glossolalia or speaking in tongues—a way for the author to express some offbeat creativity. Or perhaps it's a sacred text from an alien planet. No one really knows.

The Caesar cipher is often called shift cipher. Like the ROT1 system, it simply substitutes one letter for another…but you need a way to know exactly which letter another letter stands for, otherwise you'll never understand the message.

Caesar didn't want military intelligence falling into the wrong hands. His cipher worked, but in large part because many of his opponents couldn't read.

A Vigenère cipher interweaves multiple Caeser ciphers to create a code that's even tougher to crack. It's also called polyalphabetic substitution, and for hundreds of years no one could figure out how to break these codes.

In the middle of the 16th Century, a man named Giovan Battista Bellaso explained the first of what are now called Vigenère ciphers. His method made it easy to substitute one polyalphabetic symbol for another—and very hard for anyone to read his secret messages.

Confederate officers often relied on Vigenère ciphers, which were easy to create using special brass cipher disks. But the Union had enough resources to routinely crack the codes.

In 1586 Mary plotted to kill Queen Elizabeth I. Unfortunately for Mary, one of the Queen Elizabeth's men cracked the code. Mary was imprisoned and ultimately executed.

The police found a dead body with a message sewn into the man's clothes, which then led them to a book hidden his car. The book had indentations of a secret code. The incident became known as the Tamam Shud case.

The famous Tamam Shud case has never been solved. No one knows who killed the man. And no one has ever been able to crack the supposed secret code, either.

Many experts have tried and failed to comprehend the strange code. Some of the most recent attempts have concluded that the code isn't really secret, it's just shorthand for something that no decryption method will ever understand.

Rail Fence is a type of transposition cipher. It's written in a downward fashion on rows of lines. Once you get to the bottom of the line, you read upwards until arriving at the top line, and then repeat the process to see the entire message.

Fenn developed his riddle as a poem, which ends with this stanza: "So hear me all and listen good, your effort will be worth the cold. If you are brave and in the wood, I give you title to the gold." Whoever can decipher the meaning of the full poem should be able to find a fancy bronze box filled with treasure.

Fenn, who is still alive and in his 80s, was inspired to bury the treasure when he was diagnosed with cancer. Now he delights in hearing stories about treasure hunters who are searching for his pile of gold. Many people contact him for clues regarding the secret code, but he is very sparing with his hints.