Passwords should never be stored as plaintext or even encrypted — they must be hashed with a slow, salted algorithm (bcrypt, scrypt, or Argon2). This guide explains why and shows you how proper password hashing works.
Developers building authentication systems, security engineers auditing code, and anyone curious about how their passwords are protected (or not) in databases.
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How to Password Hashing — Why & How to Hash Passwords Securely
- Understand: hashing is one-way (cannot be reversed), encryption is two-way
- Never use MD5 or SHA-256 alone for passwords — they are too fast
- Use bcrypt (cost 12+), scrypt, or Argon2id for password hashing
- Always add a unique salt per password (bcrypt does this automatically)
- Store only the hash + salt in your database — never the plaintext
- To verify login: hash the input and compare with stored hash
Pro Tips
- bcrypt cost factor 12 takes ~250ms per hash — fast enough for login, slow enough to stop brute-force
- Each password gets a unique random salt — prevents rainbow table attacks
- Never roll your own password hashing — use battle-tested libraries
- Argon2id is the current state of the art (winner of Password Hashing Competition 2015)
Frequently Asked Questions
Why not just encrypt passwords?
If your encryption key is stolen (along with the database), all passwords are exposed at once. Hashing is one-way — even with the hash, the password cannot be recovered. Each must be brute-forced individually.
Why is SHA-256 bad for passwords?
SHA-256 is too fast — GPUs can compute billions of SHA-256 hashes per second. Bcrypt/scrypt/Argon2 are intentionally slow (hundreds of milliseconds), making brute-force impractical.
What is password salting?
A salt is random data added to each password before hashing. It ensures two users with the same password get different hashes, and prevents precomputed rainbow table attacks.
What is the best password hashing algorithm in 2026?
Argon2id (recommended by OWASP). Bcrypt is still excellent and widely supported. Scrypt is good but less common. Never use MD5, SHA-1, or plain SHA-256 for passwords.
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