Exam-style question
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Describe how symmetric and asymmetric encryption can be used together when two parties communicate securely. Include the purpose of key exchange, digital certificates and digital signatures.
Model answer
What a good answer should say
- Symmetric encryption uses the same key to encrypt and decrypt data, so both parties need access to the same secret key.
- The difficulty is exchanging that key securely.
- Asymmetric encryption uses a public key and a matching private key.
- The public key can be shared, while the private key is kept secret.
Explanation
Why this works
The answer should explain why the two encryption methods may be combined: asymmetric encryption helps with the key exchange, while symmetric encryption can then protect the communication. Certificates support trust in a public key, and signatures support origin and integrity.
Common mistake
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