Cisco Certified Network Associate (CCNA) Practice Exam

What distinguishes symmetric key cryptography from asymmetric key cryptography?

1. Symmetric requires separate keys for encryption and decryption

2. Asymmetric is generally slower

3. Symmetric uses a single key for both processes

4. Asymmetric is used for bulk data encryption

The correct answer is: Symmetric uses a single key for both processes

Symmetric key cryptography is characterized by the use of a single key for both the encryption and decryption processes. This means that the same secret key must be shared between the parties involved in communication, making it essential for both parties to have access to this key ahead of time. This single-key mechanism allows for faster encryption and decryption processes compared to asymmetric key cryptography, where different keys are used for each process. In symmetric key cryptography, because only one key is in play, operations can be performed more quickly and with less computational overhead, which makes it suitable for scenarios requiring speed, such as encrypting large amounts of data. This contrasts with asymmetric key cryptography, which uses a key pair (a public and a private key) that enhances security but at the cost of speed. While several other statements could describe characteristics of either symmetric or asymmetric key cryptography, they do not accurately convey the hallmark feature of symmetric key cryptography, which is the single key utilized for both encryption and decryption.