Book Cipher

Each sequence of numbers is constructed of a page number, a line number, and a word number in a given text (which is the key). Sometimes, the page number is elided and/or a character number is added. Simple, albeit time-consuming.

35 9 1 / 511 12 1 / 262 1 7

Here the key is The Time Traveler's Wife by Audrey Niffenegger.

I / love / you

What strikes me about book ciphers is the key.

The premise of the book cipher, in my opinion, is that both parties have read the same book. The key represents an overlap in their shared experience, and their ways of thinking. The key is as much a message as the plaintext. It says: we are the same. we share an experience, and so, we share a language.

Tactile Ciphers

One fun feature of classical ciphers is the opportunity to puzzle out the code in physical space.

For example: the scytale is a cipher tool dating back to the ancient Greeks. The encoded message is written on a long strip of parchment. This is then wrapped around a rod, the scytale itself. If the scytale is the correct thickness, the message is revealed by reading across.

If you know the trick, the code can be easily cracked brute force. But even if you don't know, there's a tactile element to a strip of parchment that invites you to play with it until it's cracked.

Same goes for the rail fence cipher, or various grille ciphers; once you bring these codes into a physical, tactile space, the human brain starts to think about them differently.

a lego Reihenschieber from Klaus Schmeh's own blog

Semaphore

Today I learned that "semaphore" does not only refer to the flag language. That is "flag semaphore", but all long distance visual communication apparatuses are technically semaphore devices.

Other forms of semaphore include visual morse (such as with a signal lamp), smoke signals, and the optical telegraph. It turns out, telegraphy is also an umbrella term for any form of long distance communication that doesn't involve passing a physical message to the recipient, of which the electrical telegraph is just one possible variant. I was wrong again!

By Joshi1983 - Own work, CC BY-SA 4.0, Link

I was very excited to learn that Japanese has its own semaphore alphabet. Googling "Japanese flag semaphore" led me very quickly to a site called "Axis Militaria" with listings for WWII artifacts. I didn't inve𐘇tigate further on my work computer but wtf?

Codes versus Ciphers

A code transforms information. A cipher transforms information for the purpose of secrecy.

The Caesar Cipher is a code and a cipher.

The Magic Marker System is a code, but not a cipher.

Binary is also a code, and not a cipher... unless of course you are using it to communicate with another programmer, in a room full of non-programmers, to ensure the secrecy of your message. In which case, you are using binary as a cipher.

Consider The Mammoth Book of Secret Codes and Cryptograms: Over 600 Mystery Codes to Be Cracked!

The front cover claims the book contains "Da Vinci style codes and ciphers". But if a cipher is written "to be cracked!" is it actually a cipher? Can this book contain any ciphers at all, if they are designed to be solved?

This is what cats sound like