Question

Difficulty: MediumCryptographic Concepts and Algorithms

A security administrator is evaluating enterprise cryptographic standards across various system modules. Match each cryptographic algorithm or mechanism on the left with its primary operational security application on the right.

  • PBKDF2 (Password-Based Key Derivation Function 2)Mitigates offline brute-force attacks on stored hashes using configurable iteration counts and salting.
  • ECDHE (Elliptic Curve Diffie-Hellman Ephemeral)Provides perfect forward secrecy during transport layer key exchange across untrusted networks.
  • HMAC-SHA256Verifies data integrity and message origin authenticity using a symmetric shared secret.
  • AES-CBC with PKCS#7 PaddingProvides bulk symmetric confidentiality for fixed-size block payloads.

Answer

PBKDF2 matches with mitigating offline brute-force attacks via key stretching. ECDHE matches with providing perfect forward secrecy during key exchange. HMAC-SHA256 matches with verifying data integrity and authenticity via a shared key. AES-CBC with PKCS#7 matches with bulk symmetric confidentiality for block payloads.
Each cryptographic mechanism is accurately matched to its intended operational function based on core security engineering principles: PBKDF2 hardens password authentication via key stretching; ECDHE provides ephemeral session key establishment with forward secrecy; HMAC-SHA256 delivers keyed integrity and authentication; and AES-CBC provides bulk block cipher confidentiality.

Step-by-Step Solution

1
Analyze PBKDF2 function
Identified key stretching mechanism designed specifically to harden password hashes against brute-force attacks.
PBKDF2 applies salting and high iteration counts to increase computational cost per cracking attempt.
2
Analyze ECDHE mechanism
Identified ephemeral asymmetric key exchange algorithm providing perfect forward secrecy.
Ephemeral key generation guarantees that session keys are temporary and independent.
3
Analyze HMAC-SHA256 function
Identified keyed-hash message authentication code.
Combining a symmetric key with SHA-256 guarantees both integrity and message origin verification.
4
Analyze AES-CBC with PKCS#7 padding
Identified symmetric block cipher operating mode with padding.
AES-CBC encrypts 128-bit block units sequentially, requiring padding to fill incomplete final blocks.

Key Concept

Operational application of cryptographic primitives and key management mechanisms
Rate this question