I thought I would provide some info on a few of the ciphers we’ve encountered so far in the game, as well as ones that we may encounter in future game installments. A lot of this information can be found on the excellent website Practical Cryptography. Most of the ciphers we’ve encountered are classical ciphers.
Simple Substitution Cipher & Frequency Tables
The magic language. We could tell from the way this code was written that each symbol likely represented a single letter, which means it was a simple substitution cipher (one symbol/letter = one letter). More complex substitution ciphers can use a letter or symbol to represent groups of letters or phonemes, but fortunately this first code didn’t do that to us!
Darby used the frequency of the symbols to crack the magic language. With this method, you examine your sample text to see which letters appear most frequently–those are likely the letter E. Second is likely T or A, etc. Here’s a frequency table that can help us if we encounter this again.
Caesar Cipher – ROT13 – Shifting/Transposition Ciphers
We’ve encountered this several times in the game. Simply shift the letters of the encoded text by a certain number to get the message. HI GUYS with a shift of +4 would be LMKYCW. There’s an encoder/decoder on this page.
Vigenère Cipher – Running Key Cipher
The bane of Box 3 was the Running Key cipher! The running key cipher is a variant of Vigenère. Both are polyalphabetic substitution ciphers that use tables to encode/decode messages. The main difference between them is that the running key cipher uses a long string of text to encode messages, while Vigenère uses a single word that repeats. They both use that big crazy table, the tabula recta. If we encounter another set of letters that don’t appear to be shifted in any discernible pattern and we have a keyword that seems important, we should consider using a Vigenère cipher. Here’s a good explanation of how it works.
Ciphers We’re Likely To Encounter
I wouldn’t be surprised to find any of the following ciphers in future installments. There are, of course, many more ciphers than these, but these are all easily worked by hand and relatively common. Some others can be found here.
- Rail fence cipher
- Polybius square cipher
- Baconian cipher
- Playfair cipher / Foursquare cipher
- Columnar transposition cipher
Codes
We’ve already seen semaphore flags used. I am looking forward to seeing binary, Morse code, Braille, and possibly ASL!
If we do encounter Morse Code I highly recommend using the Morse Code Decoding Tree instead of trying to use a table. It is way easier.