ENCRYPTION

Topics from the Cambridge IGCSE (9-1) Computer Science 0984 syllabus 2023 - 2025

OBJECTIVES
2.3.1 Understand the need for and purpose of encryption when transmitting data
2.3.2 ​Understand how data is encrypted using symmetric and asymmetric encryption

ALSO IN THIS TOPIC
2.1.1 METHODS OF DATA TRANSMISSION
2.1.2 METHODS OF DATA TRANSMISSION
2.1.3 METHODS OF DATA TRANSMISSION
2.2 METHODS OF ERROR DETECTION
 YOU ARE HERE | 2.3 ENCRYPTION
TOPIC 2 KEY TERMINOLOGY
TOPIC 2 ANSWERS
TOPIC 2 TEACHER RESOURCES (CIE)

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THE NEED FOR ENCRYPTION

Encryption is a process used to secure data during transmission by converting the original data into a coded form that cannot be easily understood by unauthorized users. The purpose of encryption is to protect sensitive or confidential information from unauthorized access or theft, particularly when it is being transmitted over networks, such as the Internet.

There are several reasons for the need for encryption in data transmission:

• Confidentiality: Encryption helps to protect the confidentiality of sensitive information by preventing unauthorized access to the data.
• Integrity: Encryption helps to ensure the integrity of data during transmission by detecting any unauthorized changes or modifications to the data.
• Authentication: Encryption can be used to verify the identity of the sender or receiver of data, providing a level of authentication that helps to prevent fraudulent activity.
• Privacy: Encryption can be used to protect the privacy of users by ensuring that their personal or sensitive information is kept confidential.
• Compliance: Encryption may be required by law or industry regulations to comply with data privacy and security requirements.

In summary, encryption is an important tool for protecting data during transmission and ensuring that sensitive information is kept confidential and secure.

If data was not encrypted during transmission, several problems could occur, including:

• Security breaches: Sensitive or confidential information could be easily intercepted by unauthorized users, leading to security breaches and the theft of sensitive information.
• Privacy violations: Personal or sensitive information could be exposed, leading to privacy violations and the potential for harm to individuals.
• Fraud: Unencrypted data could be easily altered or falsified, leading to fraudulent activities such as identity theft or financial fraud.
• Miscommunication: Unencrypted data could be misunderstood or misinterpreted, leading to miscommunication and potentially harmful consequences.
• Compliance violations: Organizations that handle sensitive information may be required by law or industry regulations to encrypt data during transmission, and failure to do so could result in compliance violations and financial penalties.

In summary, the lack of encryption in data transmission can lead to serious security, privacy, and compliance problems, which can have far-reaching consequences for individuals, organizations, and society as a whole.

SYMMETRIC AND ASYMMETRIC ENCRYPTION

Symmetric encryption and asymmetric encryption are two different methods used to encrypt data.

Symmetric encryption: Symmetric encryption uses a single shared key to both encrypt and decrypt data. The same key is used to encrypt the data before transmission and to decrypt the data upon receipt. The main advantage of symmetric encryption is that it is fast and efficient, making it suitable for encrypting large amounts of data. However, the main disadvantage is that the shared key must be securely exchanged between the sender and receiver, which can be difficult to do in practice.

Asymmetric encryption: Asymmetric encryption uses a pair of keys, one for encryption (public key) and one for decryption (private key). The public key is used to encrypt the data before transmission, and the private key is used to decrypt the data upon receipt. The main advantage of asymmetric encryption is that it is more secure than symmetric encryption, as the private key never has to be transmitted or shared with anyone else. However, the main disadvantage is that it is slower and less efficient than symmetric encryption, making it less suitable for encrypting large amounts of data.

In summary, both symmetric and asymmetric encryption have their own strengths and weaknesses, and the choice of which method to use depends on the specific requirements of the application and the security and performance trade-offs involved.

1. What is encryption and why is it important when transmitting data?
2. What is symmetric encryption and how does it differ from asymmetric encryption?
3. What are the advantages of using symmetric encryption in data transmission?
4. What are the disadvantages of using symmetric encryption in data transmission?
5. What are the advantages of using asymmetric encryption in data transmission?
6. What are the disadvantages of using asymmetric encryption in data transmission?
7. Can you explain the process of encrypting data using symmetric encryption algorithms?
8. Can you explain the process of encrypting data using asymmetric encryption algorithms?
9. What is the purpose of a digital signature in asymmetric encryption and how does it work?
10. What is the need for key exchange in symmetric encryption and how can it be achieved securely?

MULTIPLE CHOICE QUESTIONS
​1: What is encryption?
a. The process of converting plaintext into ciphertext
b. The process of converting ciphertext into plaintext
c. The process of converting binary into decimal
d. The process of converting decimal into binary

2: Which of the following is a type of encryption?
a. Hashing
b. Sorting
c. Searching
d. Looping

3: Which of the following is an example of symmetric encryption?
a. RSA
b. AES
c. Diffie-Hellman
d. ElGamal

4: In symmetric encryption, the same key is used for:
a. Encryption and decryption
b. Encryption only
c. Decryption only
d. None of the above

5: Which of the following is an example of asymmetric encryption?
a. RSA
b. AES
c. DES
d. Blowfish

6: In asymmetric encryption, a public key is used for:
a. Encryption
b. Decryption
c. Both encryption and decryption
d. None of the above

7: In asymmetric encryption, a private key is used for:
a. Encryption
b. Decryption
c. Both encryption and decryption
d. None of the above

8: Which of the following is a disadvantage of symmetric encryption?
a. It is slower than asymmetric encryption
b. It requires a larger key size than asymmetric encryption
c. It is less secure than asymmetric encryption
d. It requires the use of a public key

9: Which of the following is an advantage of asymmetric encryption?
a. It is faster than symmetric encryption
b. It requires a smaller key size than symmetric encryption
c. It is more secure than symmetric encryption
d. It does not require the use of a public key

10: Which of the following is a common use case for encryption?
a. Protecting personal information
b. Sorting data
c. Searching data
d. Looping through data

ALSO IN THIS TOPIC

2.1.1 METHODS OF DATA TRANSMISSION | Data Packets
2.1.2 METHODS OF DATA TRANSMISSION | Serial, Parallel, Simplex, Duplex
2.1.3 METHODS OF DATA TRANSMISSION | The Universal Serial Bus
2.2 METHODS OF ERROR DETECTION | Parity Checks, Check Sum, Check Digit, ARQ
2.3 ENCRYPTION | Symmetric and Asymmetric Encryption
TOPIC 2 KEY TERMINOLOGY
TOPIC 2 ANSWERS
TOPIC 2 TEACHER RESOURCES (CIE)