Why is Counter Block Mode (CTR) important?

• The encryption and decryption of error messages are used.
• Multiple blocks can be generated for encryption and decryption
• Data padding is available to be used when needed.
• The encryption and decryption are done in parallel.

How is Output Feedback (OFB) different than Cipher Feedback (CFB)?

• With CFB, you XOR the keystream and use the result in plain text.
• With OFB, you XOR the keystream and use the result in plain text.
• With CFB, you XOR the plain text with the keystream and use the result in a cipher text.
• With OFB, you XOR the plain text with the keystream and use the result in a cipher text.

How is Cipher feedback used?

• The Output Feedback Mode uses AES.
• All encryption is done through a Block Cipher.
• The plain text is combined with a key string.
• A 256-bit encryption is used.

When using Cipher Block Chaining (CBC), what modification to the block might be necessary?

• padding
• decryption
• substitution cipher
• encryption

What is the best way to encrypt more than one block?

• Use an Electronic Code Block Mode.
• Use Cipher Block Chaining.
• Use a P-Box Cipher
• Use the AES Standard.

What is the most important thing to keep in mind about the RC4 Cipher?

• It is generated in output feedback mode, making it independent from the plain text.
• It is a 256 byte, single 8x8 S-Box cipher that wraps numbers over 255 back to zero.
• It is a simple cipher that should be used whenever possible.
• It is an insecure cipher that should never be used in the real world.

You are experimenting with DES, Triple-DES, AES 128, and AES 256 with an SSL speed test. Which will you find runs slowest in decrypting?

• AES-128
• DES
• Triple-DES
• AES-256

Why is the AES Standard far superior to the DES Standard?

• The AES Standard uses short keys that make it immune to a brute-force attack.
• The AES Standard is a Feistel Cipher using S-Boxes and P-Boxes.
• The AES Standard has long enough keys to be immune to a brute-force attack.
• The AES Standard does not require the use of round keys.

The Data Encryption Standard (DES) uses the basics of a_____with additional algorithms?

• Simple Substitution Cipher
• P-Box Cipher
• Block Cipher
• S-Box Cipher

How does a linear feedback shift register operate?

• While the last bit of the register is outputted, the same output value is repeated, then everything is shifted to the right.
• At every tick of an internal clock the last bit is outputted, replaced by new input values, and the remaining bits are shifted to the right.
• While the last bit of the register is outputted, a new input value is inputted, which then shifts everything to the right.
• At every change in the data stream the last bit is outputted, replaced by a new input value, and the remaining bits are shifted to the right.

What do Boolean logical operators evaluate?

• zero or one
• range of numbers
• positive or negative
• true or false

Which character set provides a more flexible framework for letters and symbols than the popular Latin alphabet?

• ASCII
• UTF-16
• Unicode
• UTF-8

Which part of the message is the most vulnerable, thus needing the most protection?

• MIME
• Key (K)
• Message (M)
• Cipher text (C)