CREST CREST Cryptography & Data Protection

Question 1

Which symmetric encryption algorithm uses a 256-bit key and is approved by NIST for protecting sensitive US government data?

Accepted Answer

AES-256

Answer

AES-256 is the NIST-approved symmetric cipher used to protect sensitive and classified US government information.

Question 2

In asymmetric cryptography, what is used to encrypt data so that only the intended recipient can decrypt it?

Accepted Answer

Recipient's public key

Answer

Data is encrypted with the recipient's public key, ensuring only the holder of the corresponding private key can decrypt it.

Question 3

Which hashing algorithm produces a 256-bit digest and is recommended for integrity verification in modern CREST assessments?

Accepted Answer

SHA-256

Answer

SHA-256 produces a 256-bit hash and is currently recommended due to the collision vulnerabilities found in MD5 and SHA-1.

Question 4

What cryptographic concept ensures that a sender cannot later deny having sent a message?

Accepted Answer

Non-repudiation

Answer

Non-repudiation, typically achieved via digital signatures, prevents a sender from denying authorship of a message.

Question 5

Which protocol uses asymmetric cryptography during its handshake to establish a symmetric session key?

Accepted Answer

TLS

Answer

TLS uses asymmetric cryptography in its handshake phase to securely exchange or derive a symmetric session key for the rest of the session.

(CREST) Council for Registered Ethical Security Testers Practice Test