1.3 Compression, Encryption & Hashing Student Notebook Name: Image from:https://h50003.www5.hpe.com/digmedialib/prodimg/lowres/c04165573.png

(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

Note Taking Slide

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

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:

Research Task Student Response Explore the website below about encryption and its uses in our history as a nation. https://www.bletchleypark.org.uk/our-story 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

Research Task Student Response Read some of the information from the following site and then write a paragraph to explain how quantum cryptology works. http://science.howstuffworks.com/science-vs-myth/everyday-myths/quantum-cryptology.htm 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

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]

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.

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.

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?

Asymmetric Encryption Vocabulary Lossy Compression Lossless Compression Symmetric Encryption Asymmetric Encryption

Vocabulary Length Encoding Dictionary Coding Hashing

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