A security engineer is troubleshooting a VPN that uses a stream cipher. The VPN is experiencing intermittent failures where some packets are corrupted in transit. The engineer suspects that the same keystream is being reused. Which configuration mistake would cause keystream reuse?

Using a different key for each session

Using a block cipher mode like CBC instead of a stream cipher

Using the same nonce or IV for multiple sessions

What is a defining characteristic of a block cipher?

It requires a public and private key.

It encrypts fixed-size blocks of data.

It encrypts data one bit at a time.

It uses a different key for each block.

A secure file-sharing platform needs to support multiple recipients for each file. The platform currently encrypts the file with a symmetric key and then encrypts that key separately with each recipient's public key. However, the platform is experiencing performance issues when a file is shared with hundreds of recipients. Which optimization should be considered?

Use a single symmetric key for all recipients and share it via a secure channel.

Use a key encapsulation mechanism that allows the symmetric key to be derived from a shared secret, reducing the number of public-key operations.

Encrypt the file separately for each recipient with their public key.

Encrypt the file once with the symmetric key and encrypt the symmetric key with each recipient's public key, but cache the encrypted keys.

What is the purpose of key rotation in key management?

To allow multiple users to share the same key.

To make encryption faster by using newer keys.

To ensure the key is compatible with all encryption algorithms.

To reduce the risk of key compromise by limiting the amount of data encrypted with a single key.

EC-CouncilNetwork Defense Essentials

Domain 6Objective 3

Data Encryption Techniques NDE Practice Questions (Page 3)

Part of the Cryptography, PKI, and Data Security domain, which makes up ~15% of our current practice bank.

44questions here

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Questions 11–15

11expert · hard
A security engineer is troubleshooting a VPN that uses a stream cipher. The VPN is experiencing intermittent failures where some packets are corrupted in transit. The engineer suspects that the same keystream is being reused. Which configuration mistake would cause keystream reuse?
Select an answer first
12foundation · easy
What is a defining characteristic of a block cipher?
Select an answer first
13expert · hard
A secure file-sharing platform needs to support multiple recipients for each file. The platform currently encrypts the file with a symmetric key and then encrypts that key separately with each recipient's public key. However, the platform is experiencing performance issues when a file is shared with hundreds of recipients. Which optimization should be considered?
Select an answer first
14foundation · easy
What is the purpose of key rotation in key management?
Select an answer first
15foundation · easy
Which of the following is a common symmetric encryption algorithm?
Select an answer first

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Data Encryption Techniques NDE Practice Questions (Page 3)

Questions 11–15

A security engineer is troubleshooting a VPN that uses a stream cipher. The VPN is experiencing intermittent failures where some packets are corrupted in transit. The engineer suspects that the same keystream is being reused. Which configuration mistake would cause keystream reuse?

What is a defining characteristic of a block cipher?

What is the purpose of key rotation in key management?

Which of the following is a common symmetric encryption algorithm?

Keep studying — Cryptography, PKI, and Data Security