Which type of key is used for data encryption in PKI?

• A. A shared key
• B. A recovery key
• C. A public key
• D. A temporary key

Answer: (C)

In Public Key Infrastructure (PKI), a public key is utilized for data encryption. PKI employs a dual-key mechanism, consisting of a public key and a private key. The public key is openly distributed and can be used by anyone to encrypt data that only the corresponding private key holder can decrypt.

This system enhances security as it eliminates the need for sharing secret keys between parties, which can be susceptible to interception. When a sender encrypts a message using the recipient's public key, only the intended recipient—who possesses the matching private key—can decrypt and access the original message. This ensures both confidentiality and integrity of data exchanged over potentially insecure networks.

The other types of keys mentioned have different purposes. A shared key is typically used in symmetric encryption, where both parties share the same key for encryption and decryption. A recovery key is generally associated with data recovery processes rather than encryption. A temporary key might be employed in certain contexts, but it does not serve the specific role of securely encrypting data in a PKI scenario. Thus, the correct response revolves around the foundational role of the public key in ensuring secure communications.