Encryption

Encryption is one of the most important tools in cyber security. It protects data by converting readable information (plaintext) into an unreadable format (ciphertext) that can only be decoded with the correct key. This lesson covers symmetric and asymmetric encryption as required by the GCSE Computer Science specification.

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Why Encryption Matters

Whenever data is stored or transmitted, there is a risk that it could be intercepted or accessed by unauthorised people. Encryption protects:

• Data in transit — emails, web traffic, online banking transactions
• Data at rest — files stored on hard drives, databases, cloud servers
• Authentication — verifying that a message genuinely came from the claimed sender

Without encryption:

• Anyone on the same Wi-Fi network could read your emails
• A stolen laptop would give the thief access to all your files
• Login credentials sent to a website could be captured by an attacker

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Key Terminology