What is Argon2?
The winner of the Password Hashing Competition, designed to be resistant to GPU and ASIC-based cracking by requiring large amounts of memory.
Argon2 is the current state-of-the-art password hashing function, succeeding bcrypt and scrypt.
Why Argon2
- Memory-hard: Requires significant RAM, making GPU/ASIC attacks expensive
- Configurable: Adjust memory, time, and parallelism independently
- Three variants: Argon2d (data-dependent), Argon2i (data-independent), Argon2id (hybrid — recommended)
Compared to Other Hashing
| Algorithm | Memory-Hard | GPU-Resistant | Modern |
|---|---|---|---|
| MD5/SHA-1 | No | No | No (broken) |
| bcrypt | Partially | Partially | Aging |
| scrypt | Yes | Yes | Good |
| Argon2id | Yes | Yes | Best |
Recommended Parameters
For password hashing in 2024+:
- Memory: 64 MB minimum (more is better)
- Iterations: 3+
- Parallelism: Match available CPU cores
Where It's Used
Bitwarden, 1Password, KeePassXC, and many modern applications use Argon2id for password hashing.
Related Terms
Brute Force Attack
A trial-and-error method of cracking passwords or encryption by systematically trying every possible combination until the correct one is found. While simple in concept, brute force becomes impractical against sufficiently long, random secrets.
Hash Function
A mathematical function that converts any input data into a fixed-size string of characters (hash). Cryptographic hash functions are one-way, meaning you cannot reverse the process to recover the original data.
Key Derivation Function
A cryptographic function that derives one or more secret keys from a master secret, password, or other source of entropy. KDFs add security through computational cost and produce keys of the required length and format.
Salt
Random data added to a password before hashing to ensure identical passwords produce different hashes. Salting defeats rainbow table attacks and prevents attackers from identifying users with the same password.
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