Why can't I use SHA-256 or MD5 to hash passwords?

SHA-256 and MD5 are general-purpose cryptographic hash functions designed for speed — SHA-256 can compute billions of hashes per second on modern GPU hardware. This speed makes them unsuitable for passwords: an attacker with a leaked password database can brute-force common passwords in seconds. bcrypt, Argon2id, and PBKDF2 are intentionally slow and include automatic salting, making brute-force attacks computationally impractical. Never use fast hash functions for storing user passwords.

What bcrypt cost factor should I use in production?

OWASP recommends a minimum cost factor of 10, with 12 as the current best practice for most applications. The cost factor doubles hashing time for each increment — cost 12 takes roughly twice as long as cost 11. Benchmark on your production hardware and choose the highest factor where hash time stays under 500 ms to avoid degrading login performance under concurrent load.

Are hashes generated by this tool compatible with production libraries?

Yes. The bcrypt hashes use the `$2b$` prefix format compatible with `bcryptjs`, `bcrypt` (Node.js), `python-bcrypt`, and virtually all bcrypt libraries. Argon2id output uses the PHC string format compatible with `argon2` (Node.js), Rust's `argon2` crate, and `passlib` (Python). PBKDF2 output follows standard encoding conventions.

OmniToolsKit

Password Hash Generator

Name: Password Hash Generator
Rating: 5 (2 reviews)
Author: OmniToolsKit

Generate and verify secure password hashes

Bcrypt HashingArgon2 SupportSecure StorageCost Factor Control

Password to Hash

Password

Hashing Algorithm

Industry standard for password hashing

Cost Factor: 10

Higher values = more secure but slower (recommended: 10-12)

About this tool

Generate and verify secure password hashes using bcrypt, Argon2id, and PBKDF2 directly in your browser. This password hashing tool follows OWASP recommendations for authentication systems, helping developers implement proper credential storage and avoid dangerous hashing mistakes like using MD5 or raw SHA for passwords.

About

Secure Password Hashing with Bcrypt, Argon2id, and PBKDF2

Storing passwords securely is one of the most critical responsibilities in application development. Using a general-purpose hash function like MD5, SHA-1, or even SHA-256 for passwords is a well-documented vulnerability — these algorithms are designed to be fast, making them trivially brute-forceable with GPU attacks. Password hashing algorithms are specifically designed to be computationally expensive and include automatic salting to prevent rainbow table attacks.

This tool implements three OWASP-recommended algorithms: bcrypt (the most widely deployed, with a configurable work factor), Argon2id (the 2015 Password Hashing Competition winner, recommended for new systems), and PBKDF2 (FIPS-approved, required in regulated environments like healthcare and finance). Each algorithm generates a self-contained hash string that includes the algorithm identifier, parameters, and salt — so verification requires only the stored hash and the candidate password.

All hashing runs entirely in your browser using WebAssembly and Web Crypto APIs. Passwords and hashes never leave your device, making this tool safe for testing real credential data during development and security audits.

What makes it unique

Argon2id vs Bcrypt — Choosing the Right Algorithm

OWASP currently recommends Argon2id as the first choice for new password hashing implementations. Argon2id is memory-hard — it requires significant RAM in addition to CPU time — making it highly resistant to GPU and ASIC-based cracking attacks that can cheaply parallelize bcrypt. Bcrypt remains a strong choice for existing systems given its 25-year track record and near-universal library support. PBKDF2 should be selected specifically when FIPS 140-2 compliance is required. Work factor and iteration count should be tuned so that hashing takes 200–500 ms on target server hardware.

Common Use Cases for Password Hashing Tool

Testing Password Hash Implementation Correctness

Generate known-good hashes during development to validate that your application's bcrypt or Argon2 verification logic is working correctly before writing tests.

Choosing Work Factor for Production Systems

Compare hash generation times at different bcrypt cost factors or Argon2 memory parameters to find the right balance between security and server response time.

Security Auditing Stored Credential Formats

Identify whether existing stored hashes use secure algorithms by examining the hash prefix format (`$2b$` for bcrypt, `$argon2id$` for Argon2id, etc.).

How to Use

1
Select a Hashing Algorithm
Choose bcrypt, Argon2id, or PBKDF2. For new systems without compliance requirements, Argon2id is recommended by OWASP. For existing bcrypt systems, use bcrypt for compatibility. Select PBKDF2 only when FIPS 140-2 compliance is mandated.
2
Configure Algorithm Parameters
Set the work factor for bcrypt (default 12, recommended range 10–14) or memory/iteration parameters for Argon2id. Higher values provide stronger security at the cost of compute time. Aim for 200–500 ms hash time on your target hardware.
3
Enter a Password and Generate or Verify
Type a password to generate its hash, or enter a candidate password alongside an existing hash to verify it. The verification check uses constant-time comparison to prevent timing side-channel attacks.

Features

OWASP-Recommended Algorithm Selection
Implements bcrypt, Argon2id, and PBKDF2 — the three algorithms explicitly recommended by OWASP for new and existing authentication system implementations.
Configurable Work Factor and Parameters
Adjust bcrypt cost factor and Argon2id memory/iteration settings to tune the security-to-performance balance appropriate for your server hardware.
Hash Verification Mode
Verify a candidate password against an existing stored hash to test login logic, validate migration hashes, or audit user-supplied credential checks.

Frequently Asked Questions

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