1. 1.3 Compression, Encryption & Hashing
Student Notebook
Name:
Image from:

2. (a)Lossy vs Lossless compression.
(b)Run length encoding and dictionary coding for lossless compression.
(c)Symmetric and asymmetric encryption.
(d)Different uses of hashing.
Introduction to project
Explanation of how the robot arm works
Demonstrate setting up & basic expectations
Handing out robots and setting groups
Students attempt setup and check connection ok using Sliders

3. Note Taking Slide

4. Student Activity: Compression
Explain why compression is considered necessary for images on the web. [2]
Explain why Lossy compression techniques would not be suitable for use with files containing large bodies of text. [1]
Suggest a suitable lossless method for compressing text. [1]
Comparison
Lossy
Lossless

5. Student Activity: Compression
RLE is a pattern substitution compression algorithm. Data is stored in the format (colour, run).
(0,1), (1,5), (0,1)
(1,7),
(1,1), (0,2), (1,1),(0,2), (1,1),
(0,1), (1,1), (0,1),(1,1), (0,1), (1,1)(0,1),
(0,1), (1,1), (0,3),(1,1),(0,1)
Reassemble the encoded sequence.
What type of compression is likely to be used for the following: a website image, a zipped file or long text documents and images, a PDF instruction manual.
Website Image:
Zipped Folder of long text documents and images:
PDF instruction manual:

6. Research Task Student Response
Explore the website below about encryption and its uses in our history as a nation. Identify 5 interesting facts from the site and note them down below.
Student Response
Introduction to project
Explanation of how the robot arm works
Demonstrate setting up & basic expectations
Handing out robots and setting groups
Students attempt setup and check connection ok using Sliders

7. Research Task Student Response
Read some of the information from the following site and then write a paragraph to explain how quantum cryptology works.
Student Response
Introduction to project
Explanation of how the robot arm works
Demonstrate setting up & basic expectations
Handing out robots and setting groups
Students attempt setup and check connection ok using Sliders

8. Student Activity: Encryption
What word can be translated from the following cipher text using a key of -2: ZYBECP
State what is meant by symmetric encryption and explain with the aid of an example how it can be implemented.[4]
Explain what is meant by asymmetric encryption. [4]

9. Student Activity: Encryption
Explain why asymmetric encryption is more secure than symmetric. [2]
Governments sometimes demand copies of encryption keys so they can decrypt messages if necessary. What reasons are there for and against governments doing this? Useful story.

10. Student Activity: Encryption
Copy the code shown below into a new Python file and save it with a sensible name. Run the code.
When the shell appears after running, type on the command shown below. Replace “Hello” with something else if you want.

11. Student Activity: Encryption
Copy the hash output into Google, can you find your plaintext online?
What does this say about using common words in a password?
Try to hash some of your strings and phrases, can you find the plaintext for them online?

12. Asymmetric Encryption
Vocabulary
Lossy Compression
Lossless Compression
Symmetric Encryption
Asymmetric Encryption

13. Vocabulary
Length Encoding
Dictionary Coding
Hashing

14. Terms of use & Legal Stuff
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