encryption

Methods of Encryption

KS4 – Data Transmission

Retrieval Task

Starter Time – Retrieval Practice
What can you remember from last lesson?

➢Write information on the given sticky note – 3 mins

➢Pair up with your shoulder partner.

➢Exchange and discuss your notes - 2 mins

➢Don’t forget to Paste your sticky note on Notebook!!!

Recall and define the following terms from the previous lesson.
1.Check digits
2.Methods of check digits
3.ISBN Number

Lesson Objective:
To understand the concept of symmetric and asymmetric encryption.

Success Criteria:

Self assessment

AT

I can identify the purpose of encryption.

ABOVE

I can depict the concept of symmetric and asymmetric encryption.

ABOVE +

I can compare symmetric and asymmetric encryption.

Topic: Methods of Encryption

Keywords

Encrypt

ريفشت

Decrypt

ريفشت كف

Symmetric encryption

لثامتملا ريفشتلا

Cypher

رفياس

Asymmetric encryption

لثامتملا ريغ ريفشتلا

Public Key

ماعلا حاتفملا

Private Key

صاخلا حاتفملا

Sight words

1 minute challenge!!!

THINK ABOUT…

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

Why is it advisable by UAE government to avoid

manual records and store confidential

information on physical documents?  

The piece of paper can get

stolen, intercepted, or
recovered if it has not

been disposed of properly.

Laws might also be broken
regarding data privacy and

secrecy.

Purpose of encryption

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

Encryption alters data into a form that is unreadable by anybody for whom the data is not intended. It cannot prevent the data being intercepted, but it stops it from making any sense to the eavesdropper. This is particularly important if the data is sensitive or confidential.
The original data being sent is known as plaintext. Once it has gone through an encryption algorithm, it
produces ciphertext.

Support Material:

Encryption

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

Decrypt the text using
Caeser substitution
method

Open the given link:

CHALLENGE QUESTION??

Why is encryption essential in ensuring the security

of digital communication?

https://studio.code.org/s/pwc/lessons/8/levels/2

​FNULXVN CX HNJA 10 LB

Encryption – Progress check

_________ is a way of securing Information on a network. An __________ is used to help decrypt messages. Taking a secret message and reproducing the original plain text is known as__________. Once the plain text gone through encryption algorithm, it produces a __________.

Plain Text

Encryption

Encryption Key

Decryption

Cypher Text

Lesson Objective:
To understand the concept of symmetric and asymmetric encryption.

Success Criteria:

Self assessment

AT

I can identify the purpose of encryption.

ABOVE

I can depict the concept of symmetric and
asymmetric encryption.

ABOVE +

I can compare symmetric and asymmetric
encryption.

Progress Check1:

SC1:I can understand the purpose of encryption.

Highlight the 1st
success criteria

Symmetric Encryption

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

Symmetric encryption uses an encryption key; the same key is used to encrypt and decrypt the encoded
message. First, consider a simple system that uses a 10-digit denary encryption key (this gives 1 × 1010
possible codes); and a decryption key.

Plain text →cypher text
using 10-digit encryption

key

Now can you identify the 10 digit

encryption key used in this encryption.

Explain how it works.

Modern computers could ‘crack’ this encryption key in a matter of seconds. To try to combat this, we now use 256-bit binary encryption keys that give 2256 (approximately, 1.2 × 1077) possible combinations.
It is difficult to keep the encryption key a secret as it needs to be sent in an email or a text message which can be intercepted.

PAIR & SWAP

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

➢ Students will work in Pairs.
➢ Teacher will Provide each pair with a

unique symmetric encryption key (a simple substitution key).

➢ One student in each pair creates

secret message and encrypts it using the provided key.

➢ The encrypted message is passed to other students, who decrypts it using the same key.

CHALLENGE:

Discuss the effectiveness and limitations of

symmetric encryption based on your experience.

Asymmetric Encryption

Asymmetric encryption was developed to overcome the security problems associated with symmetric
encryption. It makes use of two keys :
» public key- made available to everybody
» private key- only known to the computer user

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

Asymmetric Encryption- Modeling

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

CRITICAL THINKING

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

Design a scenario where Tom is planning to have a communication of private information with 2 of her other friends.

Explain how Asymmetric Encryption will work
here?

Multiple Choice

Symmetric encryption is more secure than asymmetric encryption because it uses a single key.

• TRUE

• FALSE

Multiple Choice

In asymmetric encryption, the public key can be freely shared, but the private key must be kept secret.

• TRUE

• FALSE

Multiple Choice

Asymmetric encryption provides a higher level of security because even if the public key is intercepted, the private key is required to decrypt the data.

• TRUE

• FALSE

Lesson Objective:
To understand the concept of symmetric and asymmetric encryption.

Success Criteria:

Self assessment

AT

I can identify the purpose of encryption.

ABOVE

I can depict the concept of symmetric and
asymmetric encryption.

ABOVE +

I cancompare symmetric and asymmetric
encryption.

Progress Check2:

SC2:I can depict the concept of symmetric and asymmetric encryption.

Highlight the 2nd
success criteria

SYMMTERIC VS ASYMMETRIC

ENCRYPTION-CLIPS

➢Class is divided into 3 groups:

➢Each group will get one of the following
scenario.

•Secure Email Connection

•Online Shopping

•Data Transfer between two organization

➢Discus in groups and determine which
encryption method is more suitable for given scenario.

Your decision should be based on
following key points:
✓Confidentiality of data.

✓Speed of data Transfer

✓Authenticity of data.

CHALLENGE:

How effective is key generation and key distribution

method in Asymmetric encryption??

SYMMETRIC VS ASYMMETRIC

ENCRYPTION

Symmetric Encryption

Asymmetric Encryption

Symmetric encryption algorithms are generally faster and more efficient than asymmetric encryption algorithms.

Asymmetric encryption algorithms are slower than symmetric algorithms due to the complex
mathematical computations involved.

One of the main challenges in symmetric encryption is key distribution. If two parties
want to communicate securely, they need to
find a secure way to exchange the secret key.

Asymmetric encryption solves the key distribution problem. Public keys can be freely distributed, allowing anyone to encrypt messages that only the holder of the corresponding private key
can decrypt

Security risk is always there in this method.

More secure way of encryption.

Symmetric encryption is often used for
encrypting bulk data, such as files and
messages, where speed is essential.

Asymmetric encryption is used to create digital
signatures, ensuring the authenticity and
integrity of a message or document.

Support Material

Multiple Choice

When carrying out asymmetric encryption, which of the following users would keep the private key?

• the sender

• the receiver

• both sender and receiver

• all recipients of the message

Multiple Choice

In encryption, which of the following is the term used to describe the message before it is encrypted?

• simple text

• plaintext

• no text

• ciphertext

Multiple Choice

Which of the following is the biggest disadvantage of using symmetric encryption?

• it is very complex and time consuming.

• it is rarely used anymore

• the value of the key reads the same in both directions

• there is a security problem when transmitting the encryption key

Lesson Objective:
To understand the concept of symmetric and asymmetric encryption.

Success Criteria:

Self assessment

AT

I can identify the purpose of encryption.

ABOVE

I can depict the concept of symmetric and asymmetric encryption.

ABOVE +

I can compare symmetric and asymmetric encryption.

Progress Check3:

SC3:I can compare symmetric and asymmetric encryption.

Highlight the 3rd
success criteria

EXTENSION TASK- INOVATION

LO: We are learning to understand the concept of symmetric and asymmetric encryption.

You are part of a team working on a top-secret project for a government agency. The project involves sharing sensitive information between team members located in different countries. The challenge is to establish a secure communication channel to exchange critical data securely and efficiently.

Encryption Protocols Proposal:
Research and Innovate a combination of symmetric and asymmetric encryption
protocols that could be used for this secure communication channel. Think outside
the box and propose a method that minimizes the risks associated with data
integrity and security.

PLENARY - EXIT SLIP

​Exam Style-past paper questions

Q1: Give two reason why unauthorised person can not understand encyrpted data?

______________________________________________________________________________________________________________________________________________________________________________________________________

Q2: Part of encrypted text is PEA. Complete the table to show the orignal text.