CREST CREST Cryptography & Data Protection 1 — Questions and Answers
Question 1: Which symmetric encryption algorithm uses a 256-bit key and is approved by NIST for protecting sensitive US government data?
- 3DES
- AES-256 (Correct answer)
- RC4
- Blowfish
Correct answer: AES-256
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?
- Recipient's private key
- Sender's private key
- Recipient's public key (Correct answer)
- Sender's public key
Correct answer: Recipient's public key
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?
- MD5
- SHA-1
- SHA-256 (Correct answer)
- CRC32
Correct answer: SHA-256
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?
- Confidentiality
- Integrity
- Non-repudiation (Correct answer)
- Availability
Correct answer: Non-repudiation
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?
- FTP
- HTTP
- TLS (Correct answer)
- Telnet
Correct answer: TLS
TLS uses asymmetric cryptography in its handshake phase to securely exchange or derive a symmetric session key for the rest of the session.
Question 6: What is a rainbow table attack used to defeat?
- Encrypted disk images
- Hashed passwords without salts (Correct answer)
- TLS certificates
- Firewall rules
Correct answer: Hashed passwords without salts
Rainbow tables contain precomputed hash-to-plaintext mappings and are effective against unsalted password hashes.
CREST CREST Cryptography & Data Protection 1
Which symmetric encryption algorithm uses a 256-bit key and is approved by NIST for protecting sensitive US government data?