Argon2: The Gold Standard for Password Hashing

Argon2, winner of the Password Hashing Competition, represents the current gold standard for password storage. The algorithm provides three variants: Argon2d (data-dependent), Argon2i (data-independent), and Argon2id (hybrid). Argon2id combines resistance against side-channel attacks from Argon2i with the GPU-resistance of Argon2d, making it the recommended choice for password hashing.

Memory-hardness forms the core of Argon2's security model. By requiring significant memory allocation during computation, Argon2 dramatically increases the cost of parallel attacks. Attackers must provision memory for each parallel computation, limiting the effectiveness of GPU and ASIC-based attacks. The algorithm's parameters allow fine-tuning of memory usage, time cost, and parallelism to balance security with performance requirements.

Parameter selection for Argon2 requires careful consideration of threat models and available resources. OWASP recommends minimum parameters of 64 MB memory, 3 iterations, and 4 parallel threads for web applications. Higher-security applications should increase these parameters, particularly memory usage, as hardware capabilities permit. Regular parameter reviews ensure security keeps pace with advancing attack capabilities.