(ISC)2 Certified in Cybersecurity Practice Exam

Which type of encryption allows messages to be encrypted with a public key and decrypted with a private key?

1. Symmetric

2. Asymmetric

3. Both Symmetric and Asymmetric

4. Neither

The correct answer is: Asymmetric

The type of encryption that allows messages to be encrypted with a public key and decrypted with a private key is asymmetric encryption. This method utilizes a pair of keys: one public and one private. When a sender wants to secure a message, they use the recipient's public key to encrypt it. Only the recipient can decrypt this message using their corresponding private key, ensuring that only the intended recipient can read the message. This approach enhances security because the public key can be shared openly, while the private key remains confidential. Asymmetric encryption is commonly used in secure communications, such as SSL/TLS for internet security, and in digital signatures, where it allows for verification of the sender's identity and the integrity of the message. In contrast, symmetric encryption uses a single key for both encryption and decryption, meaning the key must be kept secret and securely shared between the communicating parties. Therefore, the nature of asymmetric encryption fundamentally differs from that of symmetric encryption, making the distinction critical in understanding encryption methods.