Top Secret
Codes, Ciphers, and How to Crack Them
By The Robot Book Club · 2026
61 pages · 22 ciphers · 4 chapters
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In the summer of 1586, a spy named Thomas Phelippes sat at a desk in London, staring at a letter filled with strange, scrambled symbols. It had been smuggled out of a prison hidden inside the waterproof plug of a beer barrel. The letter belonged to Mary, Queen of Scots, and she believed the symbols were completely unreadable. But Phelippes was a master code-breaker. He didn't just read her secret plot to overthrow the English queen—he forged a fake message at the very end using her own secret alphabet, trapping her co-conspirators. Before he handed the translated letter to the queen's spymaster, Phelippes drew a tiny, chilling picture on the envelope: a hangman's gallows. Mary's unbreakable code had been broken, and it was going to cost her her life.
Table of Contents
- 01
Ancient Secrets
Long before computers, generals and spies were already hiding their words. Meet the very first ciphers — a sliding alphabet, a message that only makes sense wrapped around a stick, and the clever mind who invented code-breaking itself.
- ·Caesar's Secret Shift
- ·How to Crush a Caesar Cipher
- ·The Scrambled Spartan Stick
- ·The Polybius Fire Grid
- ·The Math That Broke Every Code
- ·The Disk That Scrambled Everything
- 02
Codes at War
When countries fight, secrets win. This chapter is packed with the most famous codes in history — a machine that scrambled a message billions of ways, a code built from a language, dots and dashes flying through the air, and letters hidden inside little fences.
- ·The Typewriter That Lied
- ·The Code That Was Never Broken
- ·Talking in Dots and Dashes
- ·Secrets in the Pigpen
- ·The War of Waving Flags
- ·Secrets the Size of a Sand Grain
- 03
Still Unbroken
Here is the honest, spine-tingling truth: some codes have never been cracked. Not by spies, not by professors, not by the world's biggest computers. Nobody knows what they say — and this chapter is careful to tell you exactly how much is really known.
- ·The Statue That Stumped the CIA
- ·The Book No One Can Read
- ·The Treasure That Never Was
- ·The Composer's Secret Squiggles
- ·Why Some Codes Stay Broken Forever
- 04
Make Your Own
Now it is your turn. This chapter hands you the tools to build codes your friends will actually use — a secret alphabet from a keyword, messages you can flash across a dark room, and the unwritten rules every good spy follows. Grab a notebook. Tell no one.
- ·The Secret Keyword Scramble
- ·Talking With Flashlights
- ·Layer Your Codes For Double Security
- ·The Unwritten Rules of Spycraft
- ·The World Runs on Codes