iSACA Cybersecurity Fundamentals Certification Practice Exam

What describes asymmetric keys in cryptography?

1. Pairs of symmetric keys used for encryption

2. Complementary keys where one is public and the other secret

3. Identical keys utilized for both encryption and decryption

4. Keys that can be easily guessed if one is known

The correct answer is: Complementary keys where one is public and the other secret

Asymmetric keys in cryptography involve a fundamental concept where two distinct keys are utilized: one key is public and can be freely distributed, while the other is kept secret and known only to the owner. This complementary nature of the keys allows for secure communication; a message encrypted with the public key can only be decrypted by the corresponding private key, ensuring confidentiality and authenticity. This approach provides a way to establish secure communications, digital signatures, and key exchanges without the need for the parties to share a secret in advance. In contrast, the other choices focus on symmetric keys, identical keys, or incorrect descriptions of key security. Symmetric keys, for example, use the same key for both encryption and decryption, which lacks the security benefits provided by asymmetric keys. Additionally, using identical keys or claiming keys can be easily guessed diminishes the principle of security inherent in asymmetric encryption, where the security lies in the difficulty of deriving the private key from the public key. Thus, the description of asymmetric keys as complementary keys where one is public and the other secret accurately captures the essence of this cryptographic approach.