Cisco Cyber Security Practice Exam

What type of encryption uses a public key to encrypt and a private key to decrypt?

1. Symmetric

2. Asymmetric

3. Block

4. Hashing

The correct answer is: Asymmetric

The correct answer is focused on asymmetric encryption, which is a cryptographic method that utilizes two separate keys: a public key and a private key. In this system, the public key is used for encryption, allowing anyone to encrypt a message intended for a specific recipient. However, only the recipient, who possesses the corresponding private key, can decrypt the message, ensuring that it remains secure and confidential. This dual-key mechanism allows for enhanced security in various applications, such as secure communications and digital signatures. The fact that the private key is never shared adds a layer of security, as only the intended recipient can access the decrypted information. This property makes asymmetric encryption highly valuable in establishing secure connections over networks, particularly in protocols like SSL/TLS, which underpin secure web communications. In contrast, other types of encryption, such as symmetric encryption, use a single key for both encryption and decryption, which can lead to key distribution challenges. Block encryption refers to a method of encrypting data in fixed-size blocks but does not specifically address the key usage scenario described in the question. Hashing, on the other hand, is a one-way function that generates a fixed-size output from input data and is not reversible, therefore not applicable in the context of encryption and de