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EC-Council

312-50V12 · Question #178

You are a cybersecurity professional managing cryptographic systems for a global corporation. The company uses a mix of Elliptic Curve Cryptography (ECC) for key exchange and symmetric encryption algo

The correct answer is B. Data encryption with AES-256: Provides high security with better performance than 3DES, but not. This question tests the ability to evaluate cryptographic algorithm trade-offs in a post-quantum threat environment, balancing security strength and operational performance across symmetric encryption options.

Submitted by diego_uy· Mar 4, 2026Cryptography

Question

You are a cybersecurity professional managing cryptographic systems for a global corporation. The company uses a mix of Elliptic Curve Cryptography (ECC) for key exchange and symmetric encryption algorithms for data encryption. The time complexity of ECC key pair generation is O(n^3), where 'n' is the size of the key. An advanced threat actor group has a quantum computer that can potentially break ECC with a time complexity of O((log n)^2). Given that the ECC key size is 'n=512' and varying symmetric encryption algorithms and key sizes, which scenario would provide the best balance of security and performance?

Options

  • AData encryption with AES-128: Provides moderate security and fast encryption, offering a balance
  • BData encryption with AES-256: Provides high security with better performance than 3DES, but not
  • CData encryption with 3DES using a 168-bit key: Offers high security but slower performance due
  • DData encryption with Blowfish using a 448-bit key: Offers high security but potential compatibility

How the community answered

(34 responses)
  • A
    6% (2)
  • B
    65% (22)
  • C
    9% (3)
  • D
    21% (7)

Why each option

This question tests the ability to evaluate cryptographic algorithm trade-offs in a post-quantum threat environment, balancing security strength and operational performance across symmetric encryption options.

AData encryption with AES-128: Provides moderate security and fast encryption, offering a balance

AES-128 provides only 128-bit security, which under Grover's quantum algorithm is effectively reduced to 64-bit security, making it insufficient against the quantum threat actor described in the scenario.

BData encryption with AES-256: Provides high security with better performance than 3DES, but notCorrect

AES-256 provides 256-bit symmetric key strength, which aligns with NIST post-quantum recommendations since symmetric encryption generally requires doubling key size to maintain security against quantum attacks (Grover's algorithm reduces effective security to 128 bits, still considered secure). AES-256 benefits from hardware acceleration (AES-NI) on modern processors, making it significantly faster than 3DES while offering superior security. This makes it the optimal balance of quantum-resistant security and high performance compared to all other listed options.

CData encryption with 3DES using a 168-bit key: Offers high security but slower performance due

3DES with a 168-bit key is considered legacy and deprecated by NIST due to its vulnerability to Sweet32 birthday attacks, and its triple-pass design results in significantly slower performance compared to AES, making it a poor choice for both security and performance.

DData encryption with Blowfish using a 448-bit key: Offers high security but potential compatibility

Blowfish with a 448-bit key, while offering a large key size, has known weaknesses including a 64-bit block size vulnerable to birthday attacks and poor industry support, leading to significant compatibility issues in enterprise environments.

Concept tested: Post-quantum symmetric encryption algorithm selection and trade-offs

Source: https://csrc.nist.gov/projects/post-quantum-cryptography

Topics

#cryptography#AES#ECC#quantum computing#key strength

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