Chapter 4

Which three protocols use asymmetric key algorithms? (Choose three.)

• Secure Shell (SSH)

• Pretty Good Privacy (PGP)

• Secure Sockets Layer (SSL)

• Advanced Encryption Standard (AES)

Answer explanation

Refer to Chapter 4 - Slides 9 - Symmetrical versus Asymmetrical Encryption
Four protocols use asymmetric key algorithms:
1) Internet Key Exchange (IKE), which is a fundamental component of IPsec Virtual Private Networks (VPNs).

2) Secure Socket Layer (SSL), which is a means of implementing cryptography into a web browser.

3) Secure Shell (SSH), which is a protocol that provides a secure remote access connection to network devices.

4) Pretty Good Privacy (PGP), which is a computer program that provides cryptographic privacy and authentication to increase the security of email communications.

What term is used to describe concealing data in another file such as a graphic, audio, or other text file?

• steganography

• cryptography

• data masking

Answer explanation

Refer to Chapter 4 - Slides 24 - Steganography
Steganography conceals data (the message) in another file such as a graphic, audio, or other text file. The advantage of steganography over cryptography is that the secret message does not attract any special attention. No one would ever know that a picture actually contained a secret message by viewing the file either electronically or in hardcopy.

Which asymmetric algorithm provides an electronic key exchange method to share the secret key?

• WEP

• DES

• RSA

• Diffie-Hellman (DH)

Answer explanation

Refer to Chapter 4 - Slides 7 - Public-Key Encryption
Diffie-Hellman - provides an electronic exchange method to share the secret key. Secure protocols, such as Secure Sockets Layer (SSL), Transport Layer Security (TLS), Secure Shell (SSH), and Internet Protocol Security (IPsec), use Diffie-Hellman.

What encryption algorithm uses one key to encrypt data and a different key to decrypt data?

• symmetric

• asymmetric

• transposition

• one-time pad

Answer explanation

Refer to Chapter 4 - Slides 5 - Overview
Asymmetric algorithms - Asymmetrical encryption algorithms use one key to encrypt data and a different key to decrypt data. One key is public and the other is private. In a public-key encryption system, any person can encrypt a message using the public key of the receiver, and the receiver is the only one that can decrypt it using his private key. Parties exchange secure messages without needing a pre-shared key. Asymmetric algorithms are more complex. These algorithms are resource intensive and slower to execute.

Which three devices represent examples of physical access controls? (Choose three.)

• locks

• firewalls

• swipe cards

• video cameras

Answer explanation

Refer to Chapter 4 - Slides 13 - Types of Access Control
Examples of physical access controls include the following:
- Guards monitor the facility
- Fences protect the perimeter
- Motion detectors detect moving objects
- Laptop locks safeguard portable equipment
- Locked doors prevent unauthorized access
- Swipe cards allow access to restricted areas
- Guard dogs protect the facility
- Video cameras monitor a facility by collecting and recording images
- Mantraps allow access to the secured area after door 1 closes
- Alarms detect intrusion

What encryption algorithm uses the same pre-shared key to encrypt and decrypt data?

• hash

• symmetric

• asymmetric

• one-time pad

Answer explanation

Refer to Chapter 4 - Slides 5 - Overview
Symmetric algorithms - These algorithms use the same pre-shared key, sometimes called a secret key pair, to encrypt and decrypt data. Both the sender and receiver know the pre-shared key before any encrypted communication begins. 

A warning banner that lists the negative outcomes of breaking company policy is displayed each time a computer user logs in to the machine. What type of access control is implemented?

• detective

• deterrent

• masking

• preventive

Answer explanation

Refer to Chapter 4 - Slides 19 - Types of Security Controls
Deterrent Controls - A deterrent is the opposite of a reward. A reward encourages individuals to do the right thing, while a deterrent discourages them from doing the wrong thing. Cybersecurity professionals and organizations use deterrents to limit or mitigate an action or behavior. Deterrents do not always stop these actions. 

What type of cipher encrypts plaintext one byte or one bit at a time?

• stream cipher

• block cipher

Answer explanation

Refer to Chapter 4 - Slides 6 - Private-Key Encryption (In Note Pane)
Stream Ciphers
Unlike block ciphers, stream ciphers encrypt plaintext one byte or one bit at a time. Think of stream ciphers as a block cipher with a block size of one bit. With a stream cipher, the transformation of these smaller plaintext units varies, depending on when they are encountered during the encryption process. Stream ciphers can be much faster than block ciphers, and generally do not increase the message size, because they can encrypt an arbitrary number of bits.

Which type of cipher is able to encrypt a fixed-length block of plaintext into a 128-bit block of ciphertext at any one time?

• stream cipher

• block cipher

Answer explanation

Refer to Chapter 4 - Slides 6 - Private-Key Encryption (In Note Pane)
Block Ciphers
Block ciphers transform a fixed-length block of plaintext into a common block of ciphertext of 64 or 128 bits. Block size is the amount of data encrypted at any one time. To decrypt this ciphertext, apply the reverse transformation to the ciphertext block, using the same secret key.

Which term describes the technology that protects software from unauthorized access or modification?

• copyright

• trademark

• watermarking

• access control

Answer explanation

Refer to Chapter 4 - Slides 25 - Data Obfuscation
- Software watermarking protects software from unauthorized access or modification.

- Software watermarking inserts a secret message into the program as proof of ownership.

- The secret message is the software watermark. If someone tries to remove the watermark, the result is nonfunctional code.