The result after applying an encryption key and algorithm to a message is

Computer Security — Preparation

This question tests your understanding of Computer Security, a key topic in the Computer Awareness section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.

Computer security protects computers, networks and data from theft, damage and unauthorised access. This topic covers types of malware (viruses, worms, Trojan horses, ransomware, spyware and adware), common attacks such as phishing, spoofing, denial of service (DoS) and hacking, and protective measures such as antivirus software, firewalls, encryption, strong passwords, two-factor authentication and backups. It also covers basic cryptography terms (plaintext, ciphertext, symmetric and asymmetric encryption), digital signatures, and good cyber hygiene. Exam questions often ask about the difference between similar threats. A virus attaches itself to a program and needs a user action to spread, while a worm spreads across networks on its own. A Trojan horse pretends to be useful software. A firewall monitors and filters network traffic, which is different from antivirus software. Practise the computer security questions below. Each answer includes an explanation.