Argon2 Hash Generator

Argon2 is the winner of the 2015 Password Hashing Competition and is the current state-of-the-art for password hashing. Unlike bcrypt, Argon2 is memory-hard — it requires a configurable amount of RAM, making GPU and ASIC attacks far more expensive. Argon2 also supports parallelism and has three variants: Argon2d (faster, vulnerable to side-channels), Argon2i (side-channel resistant), and Argon2id (the recommended hybrid).

Argon2 has three tunable parameters: memory cost (how much RAM to use, e.g., 64 MB), time cost (iterations), and parallelism (number of threads). OWASP recommends Argon2id with m=64MB, t=3, p=4 as a baseline. Increase memory first — it has the biggest impact on GPU resistance. Time cost trades CPU time for security. Match parallelism to your server's available threads.

The encoded format is: $argon2id$v=19$m=65536,t=3,p=1$<base64-salt>$<base64-hash>. This string contains all parameters needed to verify a password — you store only this string, not the salt separately. The version (v=19) is the Argon2 spec version. All parameters are embedded so verification always uses the correct settings.

Use Argon2id for most applications. It combines the data-dependent memory access of Argon2d with the data-independent first pass of Argon2i, providing resistance against both GPU attacks and side-channel attacks. Argon2i is for cryptographic applications like key derivation where side-channel resistance is critical. Argon2d is for cryptocurrency and proof-of-work where side channels are not a concern.

PBKDF2 is the weakest of the three — it's not memory-hard, so GPUs can attack it cheaply. scrypt is memory-hard but has a complex parameter space and doesn't support parallelism as cleanly as Argon2. Argon2id is the modern recommendation: it's simpler to configure, well-analyzed, and has first-class parallelism support. For new applications, prefer Argon2id over PBKDF2 and scrypt.