Distance Learners:
Below is the lesson plan that you usually see me write on the dry erase board in class.
I have set up the exact same class on a Google Doc in your CSP class folder. This will allow you to enter "Journal" questions I pose to you and other Activities. Thus, I recommend you go straight to the Google Doc:

Access Google Doc I set up for you in your CSP folder titled:   “U4Ch1L7-SimpleEncryption”
When you complete today's class assignments, Email me at:  "john.harrington@student.sthelenaunified.org"  so that I can give you credit.

U4Ch1L7 _ Simple Encryption

Purpose: Students will understand the early forms of encryption and how they work.

Vocabulary:

• Encryption: a process of encoding messages to keep them secret, so only "authorized" parties can read it.
• Decryption: a process that reverses encryption, taking a secret message and reproducing the original plain text.
• Caesar Cipher: a technique for encryption that shifts the alphabet by some number of characters
• Cipher: the generic term for a technique (or algorithm) that performs encryption.
• Cracking Encryption: When you attempt to decode a secret message without knowing all the specifics of the cipher, you are trying to "crack" the encryption.
• Random Substitution Cipher: map every letter of the alphabet to a random different letter of the alphabet.

Journal: “In your daily life what things do you or other people like to keep a secret? Who are these secrets being kept from? How are these things kept secret?“

Activity: Caesar Cipher.
For example in Roman times Julius Caesar is reported to have encrypted messages to his soldiers and generals by using a simple alphabetic shift - every character was encrypted by substituting it with a character that was some fixed number of letters away in the alphabet.

• This message was encrypted using a Caesar Cipher (an “alphabetic shift”).Let’s see how long it takes you to Decrypt this message (Answer: Free pizza in the cafeteria.”)

serr cvmmn va gur pnsrgrevn
Ask: How difficult was it to crack? How many letter shift was it?

Visit: Code Studio.org_U4Ch1L7_ Simple Encryption
Part 1: Crack a Caesar Cipher
Go to #2 - “Crack a Caesar Cipher” and read the explanation.

• Try different messages from the pull down menu.
• Try entering your own message.

Ask: How difficult was it to crack now that you had a computational tool?

Part 2: Cracking a Random Substitution Cipher
(State:The cipher is harder to crack, but the widget will also be more sophisticated.)
Give students 10 minutes to play with the Tool.
Direct them to read the explanation of how  “Frequency Analysis.”
Then let them return to cracking the code.
Eventually, let them do a random substitution encryption and see if another student can crack.
Answer: Encrypted Message #3