Flashcards · 9618 · A Level Topic 17

Security (A Level) flashcards

6 cards on A Level Topic 17. Pick a subtopic or study them all.

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What is the difference between symmetric and asymmetric encryption?: Symmetric: the same key encrypts and decrypts, so the key must be shared securely. Asymmetric: a public key encrypts and only the matching private key decrypts.
What are plaintext and ciphertext?: Plaintext: the original readable data. Ciphertext: the data after encryption, unreadable without the key.
What do SSL and TLS provide?: Secure communication between a client and server: they authenticate the server, agree encryption keys in a handshake, and encrypt the data sent (as in HTTPS).
How is a digital signature created and checked?: The sender hashes the message to a digest and encrypts the digest with their private key. The receiver decrypts it with the sender’s public key and compares it with a fresh hash of the message.
What is a digital certificate?: An electronic document issued by a Certificate Authority that links a public key to its owner’s identity, so others can trust that the key is genuine.
What is quantum cryptography?: Using the properties of photons to send encryption keys (quantum key distribution): any attempt to intercept the key disturbs it and can be detected.