Forensic Science: Codes and Ciphers

Codes and Ciphers is a class that allows students to learn how to solve a variety of coded messages and to put those skills to the test with new codes each week.  Each session will focus on a different type of code or a different twist on a standard substitution type cipher.  In addition to codes and ciphers that students solve in class, I will provide an additional challenge each week for students who want to work on codes outside of class.

We will cover coding techniques dating back thousands of years up to straightforward substitution ciphers (“cryptograms”) and on to wildly complex math-based codes.  We will explore unique cryptographic creations involving digital images, a series of boxes that act as code symbols, a “paint by numbers” code that reveals an answer when the correct key is used, and the use of road maps or star maps as parts of codes.  

There will also be some sessions that focus on solutions to ciphers in real forensic cases, such as the Zodiac, a case that includes many different cryptologic techniques.

The first five sessions of the class will be:

Week of May 20:  Substitution Ciphers.  We will discuss simple mono-alphabetic keys (one letter replaces one letter) and then solve an encrypted message by figuring out the relevant key.

Week of May 27:  Substitution Ciphers with Twists:  We will examine ways to make a key more difficult, such as using non-alphabetic symbols, using a letter as a symbol for itself (to confuse the codebreaker), or using multiple symbols (or letters) for one letter that is common.  We will then apply this information to a coded message and arrive at a solution.

Week of June 3:  Transposition Ciphers.  We will discuss ways to move the letters in a message in a consistent way to encrypt a message without changing any letters to different symbols.  The simplest versions of transposition would be to write the message backwards or to put it in a grid and to write it downward.  We will examine more difficult methods, such as moving each letter a set number of places ahead in a graph-paper based grid.  We will work through multiple short transposition cipher in this session.

Week of June 10:  The Ancient Methods.  We will discuss the basics of gematria, temurah, and notarikon.  Then, using these techniques, we will decode several short messages.  For this session, we will use the “simple gematric key,” rather than more “elegant” keys that give us more freedom to play around with the final version of a coded message.

Week of June 17:  Gematria Case Study – The Zodiac.  We will discuss the Zodiac’s gematric key, which allowed for multiple methods to invert the alphabet on top of the number-based coding that gematria typically allows.  We will also discuss the Zodiac’s creation of a new variant of gematria which allowed him to create entire documents that decoded simply to his name.  We will focus on the “13 Hole Postcard” and the Mt. Diablo map and 32-symbol cipher combination.

This class will be a Socratic Discussion type of course, with significant time in each session for learners to work on and solve ciphers that I provide.  Optional assessments will be based on participation in discussions and decryption exercises.

This class is related to my primary specialty in forensic science, which is cryptology.  I have completed the most thorough cryptanalysis of the writings of the Zodiac that has ever been done, and my work will be published later in 2024.