In private key encryption, which statement is true?

In private key encryption, which statement is true?

• A. Same key is used for encryption and decryption
• B. Different keys are used for encryption and decryption
• C. It relies on a public-key infrastructure
• D. It is always quantum-resistant

Answer: (A)

In symmetric (private key) encryption, the same secret key is used to both encrypt and decrypt the data. This single shared key makes the process fast and efficient, with algorithms like AES repeatedly used in practice. The catch is that the key must be securely shared and kept secret by both parties before any communication happens; if someone else learns the key, they can both read and alter the messages. This approach is different from systems that rely on a public-key infrastructure, where separate keys are used for encryption and decryption and keys are distributed in a different way. Also, claiming it is always quantum-resistant isn’t accurate, because quantum attacks can reduce the effective security of symmetric keys unless you use longer keys or other countermeasures. So, the statement that the same key is used for encryption and decryption correctly describes private key (symmetric) encryption.

In symmetric (private key) encryption, the same secret key is used to both encrypt and decrypt the data. This single shared key makes the process fast and efficient, with algorithms like AES repeatedly used in practice. The catch is that the key must be securely shared and kept secret by both parties before any communication happens; if someone else learns the key, they can both read and alter the messages.

This approach is different from systems that rely on a public-key infrastructure, where separate keys are used for encryption and decryption and keys are distributed in a different way. Also, claiming it is always quantum-resistant isn’t accurate, because quantum attacks can reduce the effective security of symmetric keys unless you use longer keys or other countermeasures.

So, the statement that the same key is used for encryption and decryption correctly describes private key (symmetric) encryption.