Draw This - beginner

Draw a flowchart that shows the basic steps of encrypting a message using a simple substitution cipher. Start with the original message, then show how each letter is replaced by another letter, and end with the encrypted message.

10 minutes

Hint 1

Hint 2

Hint 3

Hint 4

Hint 5

Hint 6

Grading Criteria

Start and End symbols present

Process box for reading the original message

Loop structure to process each letter

Process box for replacing letters

Output box for encrypted message

Flow direction is clear and logical

All letters of the message are processed

Solution

  _______          ___________          ____________          ____________          _______
 / Start \        | Read Msg |        | For each  |        | Replace   |        | Output |
 \_______/        |__________|        | letter in |        | letter   |        | Encrypted|
      |                     |         | message   |        | with     |        | message |
      v                     |         |__________|        | substitute|        |_________|
  ___________               |               |               |               |
 | Initialize |<-------------               |<--------------               |
 | encrypted  |                                |                               |
 | message =  |                                |                               |
 | empty      |                                |                               |
 |____________|                                |                               |
      |                                        |                               |
      v                                        v                               v
  ___________        Yes?  letter left?  ---------> Replace letter ---------> Add to encrypted
 | Loop start|------------------------------->| message string             |
 |__________|                                |_____________________________|
      | No
      v
  _______
 / End   \
 \_______/

This flowchart starts with the Start symbol. Then it reads the original message. It initializes an empty string to hold the encrypted message. Next, it loops through each letter of the original message. For each letter, it replaces it with a substitute letter according to the cipher rules. The substituted letter is added to the encrypted message string. This loop continues until all letters are processed. Finally, the encrypted message is output, and the flowchart ends.

This shows the basic idea of encryption: transforming readable text into coded text by replacing letters.

Variations - 2 Challenges

[intermediate] Draw a flowchart for decrypting a message encrypted with a simple substitution cipher. Start with the encrypted message and end with the original message.

[advanced] Draw a flowchart for encrypting a message using a Caesar cipher with a shift of 3. Show how each letter is shifted by 3 positions in the alphabet.