Welcome to Day 2 at CAMP 2020. It is raining in most of the places where our CAMPers are. What a chilly day to stay dry, make new friends, and learn cryptography under creative settings!
Things started coming together today. Our instructors prepared different plans for their groups. In the TAN and COT sections of Computer Science, Matt Goehrig reviewed some commands with his students. They discussed Numify and the If statement before revealing the topic of Day 2: creating your own Caesar Cipher.
Caesar Cipher, or Caesar’s Cipher, refers to one of the most straightforward and widely known encryption techniques. It is a type of substitution cipher. Each letter in the plaintext is replaced by a letter with specific predetermined numbers of positions down the alphabet.
Although students have learned how to manually encrypt and decrypt with Caesar Cipher, programming the cipher into digital code still provides a lot of conveniences. If CAMPer wants to quickly encode a long plaintext to their friend, they can now build a computer program. This also enables the recipient to decode a complicated cipher text without hours of labor.
To program a Caesar cipher into the Python computer language, Matt asked the students to build a flow chart of their plan, adding the functions they needed and putting each command in the right sequence.
- Turn the message into numbers
- Add the secret number to each number
- Turn that into letters
At the COT group, Matt chose the message “BardMathCamp” and the secret number 11 as examples during his demo. CAMPers utilized the commands they learned yesterday to successfully synthesize them into a pair of encryption/decryption algorithms: a simple Caesar Cipher program. The group also modified the code to translate complete paragraphs of plaintext.
For the art class, SIN, CSC, and COS sections created Zoom backgrounds with Pixel Studio, a pixel art editor commonly used by artists and game developers.
We asked the students to install the app before our class. So that they can get to know the app and be prepared for future courses, Chelsea Cai leads CAMPers step by step through screen share on Zoom. CAMPers first created three layers and explored with the tools, including gradients, pencil, fill, etc.
At the SEC, TAN, and COT groups of the art class, students had a hands-on experience creating abstract art ciphers with the Pigpen Code, the Red/Blue code, and the Crease code. Unlike most of the cryptographic methods we encountered, the pigpen cipher uses symbols instead of letters. Students learned to exchange letters for symbols, which are fragments of a grid.
(example of a Pigpen Cipher)
This cipher method was used by the Freemasonry and during the American civil war. Even if our encrypted text was hacked, we could always change the key by rearranging the letters in grids.
CAMPers also tried the Red/Blue code with our instructor Tiffany Smith. A red/blue system is created when the sender uses a light blue pencil to write their message. Then, they cover that message using red cross-hatching and a highlighter. The sender’s code can later only be revealed using a red piece of cellophane, which makes the light blue writing visible again.
Last but not least in Tiffany’s art class, we practiced writing a Crease Code. By folding a paper multiple times and placing the secret letters or message on the creases, this technique is somewhat tricky. It requires us to fill the blank space with words that compliment the notes and constitute a complete sentence.
In the math classroom, Erin Toliver led her class with the COS group. We practiced Modular (clock) Arithmetic, encoding, decoding of Caesar Ciphers with different shifted codes. Tomorrow, we will start pairing students for more encryption and decryption exercises.
Hosted by our TAs: Jazmin, Olivia, Yuxuan, Tsitsi, Alex, Gigi, and CAMPers themselves, the activity periods were filled with diverse projects. Raging from games like Mastermind, Jeopardy!, Zip Zap Zop, SET, to teaching the Binary Number trick, students had a relaxing and fun ending of Day 2.