Responds to a Challenge with a Secret Key and Function

In the world of cryptography, when faced with a challenge, the correct response involves utilizing a method that combines a secret key and a function to ensure security and authenticity. Let us explore the options:

a) Symmetric key encryption

A symmetric key encryption system uses the same key for both encryption and decryption processes. While efficient, it does not involve responding to a challenge with a function of a secret key.

b) Asymmetric key encryption

Asymmetric key encryption, also known as public-key encryption, involves the use of a public key for encryption and a private key for decryption. Although it uses keys, it does not directly respond to a challenge with a secret key and a function.

c) Hash function

A hash function is a one-way function that generates a fixed-size string of bytes from any input data. While crucial for data integrity and security, it does not involve responding to a challenge with a secret key.

d) Digital signature

Digital signature is the correct response. It ensures authenticity, integrity, and non-repudiation of a message.

Final answer:

A digital signature is the correct response. It ensures authenticity, integrity, and non-repudiation of a message.

Explanation:

The correct answer is d) Digital signature. A digital signature is a cryptographic technique that provides authenticity, integrity, and non-repudiation of a message. It uses the sender's secret key to create a unique and verifiable signature of the challenge. This ensures that the message has not been tampered with and can be traced back to the sender.