CompTIA Security+ SY0-701 Practice Test 4+5 By Mr.B

Which of the following answers refers to a legacy symmetric-key block cipher encryption algorithm?

• RC4

• DES

• RSA

• DSA

Answer explanation

DES (Data Encryption Standard) is a legacy symmetric-key block cipher, widely used in the past for encrypting data. RC4 is a stream cipher, while RSA and DSA are asymmetric encryption algorithms.

Which of the answers listed below refers to a deprecated stream cipher used in some legacy applications, such as WEP?

• RSA

• DES

• SSL

• RC4

Answer explanation

RC4 is a deprecated stream cipher that was widely used in legacy applications, including WEP (Wired Equivalent Privacy). Its vulnerabilities have led to its decline in favor of more secure algorithms.

What is the recommended replacement for DES?

• DSA

• RSA

• RC4

• AES

Answer explanation

AES (Advanced Encryption Standard) is the recommended replacement for DES (Data Encryption Standard) due to its stronger security and efficiency. DES is now considered insecure, while AES is widely adopted for secure data encryption.

An IV is a random or pseudorandom value used in cryptography to ensure that the same plaintext input does not produce the same ciphertext output, even when the same encryption key is used. The IV is typically used with encryption algorithms in block cipher modes to enhance security by introducing randomness to the encryption process.

• True

• False

Answer explanation

The statement is true. An IV (Initialization Vector) is essential in cryptography to ensure that identical plaintexts encrypt to different ciphertexts, enhancing security by adding randomness to the encryption process.

Which of the following answers refers to a block cipher mode that works by chaining the ciphertext blocks together, such that each ciphertext block depends on the previous block?

• CBC

• GCM

• ECB

• CFB

Answer explanation

CBC (Cipher Block Chaining) mode links ciphertext blocks, meaning each block's encryption depends on the previous one. This chaining enhances security compared to modes like ECB, where blocks are independent.

Which of the block cipher modes listed below is the simplest/weakest and therefore not recommended for use?

• CBC

• GCM

• ECB

• CTM

Answer explanation

ECB (Electronic Codebook) mode is the simplest block cipher mode but is considered weak because it encrypts identical plaintext blocks into identical ciphertext blocks, making it vulnerable to pattern analysis. Therefore, it is not recommended.

Which block cipher mode combines CTM for encryption with an authentication mechanism to ensure both data confidentiality and integrity?

• CBC

• GCM

• ECB

• CFB

Answer explanation

GCM (Galois/Counter Mode) combines counter mode encryption with an authentication mechanism, ensuring both confidentiality and integrity of the data. This makes it the correct choice compared to CBC, ECB, and CFB.

In cryptography, the number of bits in a key used by a cryptographic algorithm is referred to as key size or key length. The key length determines the maximum number of combinations required to break the encryption algorithm, therefore typically a longer key means stronger cryptographic security.

• True

• False

Answer explanation

True. A longer key length increases the number of possible combinations, making it harder to break the encryption, thus enhancing cryptographic security.

Which of the following answers refers to an embedded microcontroller used for secure boot, disk encryption, and system integrity verification?

• TPM

• SoC

• UEFI

• HSM

Answer explanation

TPM (Trusted Platform Module) is an embedded microcontroller that provides secure boot, disk encryption, and system integrity verification, making it the correct choice for the question.

In a Kerberos-protected network, this type of secure token is granted to users during their initial login to enable them access to multiple network services without the need to re-enter their login credentials.

• OTP

• TGT

• AS

• TGS

Answer explanation

In a Kerberos network, a Ticket Granting Ticket (TGT) is issued to users upon initial login. This token allows users to access multiple services without re-entering credentials, making TGT the correct answer.