1.4 Cybersecurity Cryptography: Encryption and Public Key Infrastructure

Question 1

What is the definition of Public Key Infrastructure (PKI)?

Answer 1

A system of policies, procedures, hardware, and software responsible for creating, distributing, managing, storing, revoking, and processing digital certificates.

Question 2

What is the purpose of Public Key Infrastructure (PKI)?

Answer 2

To establish trust by associating a certificate to people or devices, often in conjunction with a Certificate Authority (CA).

Question 3

What is a Certificate Authority (CA)?

Answer 3

A trusted entity that issues digital certificates and vouches for the identity of the entities to whom it issues certificates.

Question 4

What is symmetric encryption?

Answer 4

An encryption method where the same single secret key is used for both encrypting plaintext into ciphertext and decrypting ciphertext back into plaintext.

Question 5

What are two alternative terms for symmetric encryption?

Answer 5

• Secret key algorithm
• Shared secret

Question 6

What is the main scalability challenge associated with symmetric encryption?

Answer 6

The difficulty in securely sharing and managing the single secret key among a growing number of individuals or devices.

Question 7

Why is symmetric encryption still widely used despite its scalability issues?

Answer 7

It is very fast and has low computational overhead compared to asymmetric encryption.

Question 8

What is asymmetric encryption?

Answer 8

An encryption method that uses two different, mathematically related keys: a public key for encryption and a private key for decryption.

Question 9

What are the roles of the public key and private key in asymmetric encryption?

Answer 9

• Private Key: Exclusively held by one person or device, used for decryption.
• Public Key: Freely distributed and available to anyone, used for encryption.

Question 10

In the encryption process, whose public key does Bob use to send a message to Alice?

Answer 10

Alice’s public key.

Question 11

Whose private key is used to decrypt the message sent from Bob to Alice?

Answer 11

Alice’s private key.

Question 12

Can a private key be derived from its corresponding public key?

Answer 12

No, it is impossible to derive or reverse-engineer the private key from the public key.

Question 13

What is key escrow?

Answer 13

The practice of storing copies of cryptographic keys with a third party or within an organizational system.

Question 14

Why might an organization implement key escrow?

Answer 14

To maintain access to encrypted data for business continuity, such as when an employee leaves or for compliance with data access requirements.

Question 15

Why is it important to protect a private key with a password?

Answer 15

To add an additional layer of security and prevent unauthorized access to the key.

Question 16

Fill in the blank: Symmetric encryption uses the same _______ for both encryption and decryption.

Answer 16

secret key

Question 17

What is the key management challenge in organizations regarding asymmetric encryption?

Answer 17

Managing hundreds or thousands of public/private key pairs.

Question 18

What are digital certificates?

Answer 18

Electronic documents used to prove the ownership of a public key.

Question 19

What does the term ‘key pair’ refer to in asymmetric encryption?

Answer 19

The set of two mathematically related keys (public and private) generated simultaneously.

Question 20

What is the ‘power and magic’ of asymmetric cryptography?

Answer 20

Anyone with the public key can encrypt data, but only the holder of the corresponding private key can decrypt it.

Question 21

What is the scalability problem in symmetric encryption?

Answer 21

The complexity of distributing keys to everyone who needs to decrypt data and tracking which key belongs to whom.

Question 22

What is the key generation process in asymmetric encryption?

Answer 22

The simultaneous creation of a public and private key pair, often involving randomization and large prime numbers.

Question 23

True or False: Asymmetric encryption uses the same key for both encryption and decryption.

Answer 23

False