Classical Algorithm Threat Models

Side-channel claim limit. Nothing on this page claims constant-time behaviour or side-channel resistance for any target: the side-channel harness covers nothing (finding A48) and no measurement exists. The Rust and C cores are designed for constant time and unmeasured; managed runtimes (JIT, GC, bounds checks) make no timing claim. Where this page names constant-time or side-channel techniques, in prose or in code, they are design intent or recommendations, not measured properties.

Comprehensive threat analysis for 30 classical cryptographic algorithms, including their vulnerabilities to quantum attacks.

Hash Functions (11 algorithms)

SHA Family

Blake Family

Specialized Hashes

Symmetric Encryption (8 algorithms)

AES Variants

ChaCha Family

International Standards

Lightweight Cryptography

Message Authentication (4 algorithms)

HMAC Variants

Polynomial MACs

Key Derivation (4 algorithms)

Digital Signatures & Key Exchange (5 algorithms)

EdDSA Variants

Transitional RSA ⚠️

Key Exchange

Random Generation & Utilities (2 algorithms)

Quantum Threat Assessment

Algorithm Category Grover Impact Shor Impact Effective Security Migration Priority
Hash Functions √n speedup None 128→64 bits Low
Symmetric Encryption √n speedup None 256→128 bits Low
MACs √n speedup None 256→128 bits Low
Key Derivation √n speedup None Varies Low
EdDSA/ECDH √n speedup Broken 0 bits Critical

Classical Attack Vectors

Implementation Vulnerabilities

Protocol-Level Attacks

Cryptanalytic Advances

Security Recommendations

For Quantum Resistance

  1. Symmetric Keys: Use 256-bit minimum (AES-256, ChaCha20-256)
  2. Hash Functions: Use 384-bit minimum for long-term security
  3. Digital Signatures: Migrate to PQC immediately
  4. Key Exchange: Migrate to PQC immediately

For Classical Security

  1. Authenticated Encryption: Always use AEAD modes
  2. Key Derivation: Use memory-hard functions for passwords
  3. Random Generation: Use hardware RNG when available
  4. Implementation: Always use constant-time implementations

Best Practices by Use Case

Data Encryption

Authentication

Password Storage

Digital Signatures (Classical)

Compliance Considerations

Standards Compliance

Regional Requirements

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