Secret codes and ciphers

A code is a system of symbols, letters, words, or signals that are used instead of ordinary words and numbers to send messages. Codes keep our secrets safe. But have you ever wondered where secret codes came from? 

Codes and ciphers make up a form of secret communication but what is the difference between a code and a cipher? Ciphers are slightly different from codes. A cipher mixes up or uses different letters or characters to disguise the message. While a code replaces words, phrases, or sentences with groups of letters or numbers. So really, a code affects the word, and a cipher affects the individual letters. And, the process of encoding then decoding a message is called cryptography.

Historically, codes have been used by politicians, spies and countries at war to prevent their enemies from knowing what they are up to. Many of the earliest codes, or “ciphers,” were easy to create by hand. Today, cryptography is essential in computer science for keeping everything from e-mails to bank account information secure.


How to Write Secret Codes Using Ciphers!

For thousands of years, ciphers have been used to hide those secrets from prying eyes in a cat-and-mouse game of code-makers versus code-breakers. These are some of history’s most famous codes.

The Voynich manuscript 

The Voynich manuscript is one of the most famous unsolved ciphers in the world. More than 600 years old, its written in an unknown language that no one has been able to translate. This extraordinary codex is filled with bizarre illustrations and written in a unique alphabet that no one has ever identified. To this day, we are not sure if the manuscript contains valuable secrets, the ravings of a madman, or is simply a centuries-old hoax.

Kryptos Puzzle

Kryptos, a sculpture built in 1991 outside the CIA building in Langley, Virginia USA, contains four coded messages – only three of which have been solved. The 12-foot copper statue displays a collection of random letters but it is a riddle for the ages. If you are looking for a job as a codebreaker, try cracking the last one - as long as you do not mind getting a visit from the Men in Black.

Caesar’s Cipher 

Julius Caesar, who ruled the Roman Empire as dictator from 49 B.C. until his assassination in 44 B.C., used a secret code to communicate with his generals. He swapped each letter for the one three spots later in the alphabet. Named after Julius Caesar, who used it to encode his military messages, the Caesar shift is as simple as a cipher gets. All you have to do is substitute each letter in the alphabet by shifting it right or left by a specific number of letters. Today, we can break this code in our sleep, but it took ancient codebreakers 800 years to learn how to crack it – and nearly another 800 years to come up with anything better.

Alberti’s disk

In 1467, architect Leon Battista Alberti described a curious device. It was a disk made up of two concentric rings. The outer ring engraved with a standard alphabet, and the inner ring, engraved with the same alphabet but written out of order. By rotating the inner ring and matching letters across the disk, a message could be enciphered, one letter at a time, in a fiendishly complex way.


When no one is left who knows how to read a language, it becomes a secret code of its own. That is exactly what happened with the hieroglyphs of ancient Egypt. These beautiful, iconic characters baffled linguists for centuries, until Napoleon’s troops discovered the Rosetta Stone, which allowed scholars to match the hieroglyphs with known Greek words, giving us the key to understanding the language and culture of one of the greatest civilizations in history.

The Enigma Machine 

Enigma is a famous encryption machine used by the Germans during WWII to transmit coded messages. The Nazi coding device was so sophisticated that some thought it would be impossible to crack. Resembling an oversize typewriter, it did not look very intimidating – but it was a formidable foe.  Its series of spinning electric rotors were mind-bogglingly good at scrambling messages. They could make each letter appear in more than 150 trillion different ways.

Alan Turing and other researchers from the Government Code and Cypher School at Bletchley Park, exploited a few weaknesses in the implementation of the Enigma code and gained access to German codebooks. This allowed them to design a machine called a Bombe machine, which helped to crack the most challenging versions of Enigma. By early 1942 the code breakers at Bletchley Park were decoding about 39,000 messages a month. At the end of the war, Turing was made an Officer of the Most Excellent Order of the British Empire (OBE) for his code-breaking work.


Do you and your friends share hidden messages or jokes that only you can understand? Then you are using Steganography! Steganography is the practice of hiding a secret message in something that is not secret. Unlike cryptography, the goal of steganography is to completely obscure the existence of information rather than conceal its content.

Since steganography is more of an art than a science, there is no limit to the ways steganography can be used. For example, it can simply be playing an audio track backwards to reveal a secret message or even playing a video at a faster frame rate (FPS) to reveal a hidden image.  

Other sneaky ways people have sent messages 


Today, people travel to the beach or a park to fly a kite just for joy of watching this colourful contraption swoop through the air. But kites used to be much more serious. They first originated in China around 1000 B.C. as military signals – their colours, patterns, and manoeuvres were used as codes to pass along information to nearby troops. Han Dynasty soldiers outfitted kites with bamboo pipes that made a frightening whistling noise when flown over the enemy. Other ancient Chinese troops used giant kites that could carry a soldier, like an early version of spy planes. Who was fearless enough to sign up for that job?   

Tattooed head – Histiataeus of Miletus

A historic usage of steganography was pioneered by Histaeius of Milan to allow him to communicate secretly with the Greeks. Histaeius would shave the head of a slave, tattoo a message on the slave's scalp, and then wait for the hair to grow back, concealing the message. The slave would then be sent to the Greeks, who would shave the slave's head and read the hidden message.


In the 1950s the US Central intelligence agency created a book of tips to teach spies ways to communicate in public in case they were being watched. One tip, lace up your sneakers. Tied one way, the laces might mean “I have information” tied another, “follow me”. The spies could communicate while everyone else probably just thought "that guy cannot tie his shoes correctly!"

Orange juice 

In 1597, John Gerard was imprisoned in the Tower of London in England by Queen Elizabeth I. He asked the warden to let him send letters written in charcoal. But then he scrawled another message on top using the juice from an orange – which was only visible when the juice was dry and the page heated. With his invisible ink, he coordinated an escape out of a window and into a boat rowed by one of his supporters.

Secret scarves

“An old lady knitting doesn’t look like a threat” says Vince Houghton, the historian and curator at the International Spy Museum in Washington D.C.  That is why during World War 1, Belgian resistance fighters asked women who lived near railways to keep track of the types of trains passing by, which gave the fighters information about the German invaders movements. The women would knit a bumpy stitch for one type of train and knit a small hole in the fabric for another. Then they would pass the cosy scarf to a soldier so the cloth could be decoded.  

Free speech

The Underground Railroad was a network of people who helped slaves escape their ‘owners’ in America in the 1800’s. They used a code to communicate, so if letters were intercepted – or slave owners overheard a conversation, or song – they would not be caught. A ‘conductor’ was a person who transported slaves; a ‘station’ was a safe hiding place; ‘cargo’ was escaped slaves; ‘heaven’ was the free country in Canada. Songs for their escape included Swing low, sweet chariot, the sweet “chariot” was code for the Underground Railroad. The song Wade in the water warned escaped slaves to get in the water so dogs would lose their scent trail. With these methods, hundreds of people escaped slavery.  

More stuff 

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