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Cryptographic Systems

Post-Quantum Cryptography (PQC)

PQC refers to cryptographic algorithms designed to be secure against the potential future threats posed by quantum computers. Traditional cryptographic algorithms are susceptible to quantum attacks, making PQC vital for future-proofing data security.

Symmetric Cryptography:

  • Susceptibility: Fairly resilient, but not immune.
  • Quantum Threat: Grover's algorithm can reduce the effective key length by half. For instance, a 256-bit key against a quantum computer is equivalent in strength to a 128-bit key against classical computers.

Every additional bit in a key, the strength is multiplied by a factor of 2. Therefore, a 256-bit key offers 2^256 times more strength than a 128-bit key. Doubling the key length doesn't merely double its strength.

Asymmetric Cryptography:

  • Susceptibility: Highly vulnerable.
  • Quantum Threat: Shor's algorithm can ⚠️ compromise public-key algorithms like RSA ⚠️ and those based on the discrete logarithm problem (including Elliptic Curve Cryptography).
  • Scaling Issue: Simply doubling key length only multiplies security by a factor of eight. This isn't a long-term solution.

Lattice-based Cryptography:

  • Resilience: Promising as a quantum-resistant cryptographic method.
  • Foundation: Based on the shortest vector problem and the closest vector problem.
  • Significance: Lattice-based schemes are predominant in research regarding post-quantum cryptography, offering hope for secure communication in a quantum world.
  • Lattice Definition: In mathematics and cryptography, a lattice is a regular grid or array of points in multidimensional space.
    • For visualization: Try searching "mathematical lattice 3D" on Google Images for illustrative examples.

Key Takeaway for CISSP Exam: When considering quantum-resistant cryptography, think "lattice-based."

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