IGCSE Computer Science 0478: 2. Data transmission: 2.2 Methods of error detection and 2.3 Encryption

**2.2 Methods of error detection: **
Candidates should be able to:
1 Understand the need to check for errors after data transmission and how these errors can occur
2 Describe the processes involved in each of the following error detection methods for detecting errors in data after transmission: parity check (odd and even), checksum and echo check
3 Describe how a check digit is used to detect errors in data entry and identify examples of when a check digit is used, including international standard book numbers (ISBN) and bar codes
4 Describe how an automatic repeat query (ARQ) can be used to establish that data is received without error

2.3 Encryption:
Candidates should be able to:
1 Understand the need for and purpose of encryption when transmitting data
2 Understand how data is encrypted using symmetric and asymmetric encryption