Bcrypt Hash Generator & Verifier

Understanding Bcrypt Password Hashing

Bcrypt is a password hashing function based on the Blowfish cipher, designed specifically for securely storing passwords. Unlike fast hashing algorithms like MD5 or SHA-1, bcrypt is intentionally slow, making it extremely resistant to brute-force attacks.

How Bcrypt Works

Bcrypt uses a technique called "key stretching" to make password cracking computationally expensive:

1. Salt Generation: A random salt is automatically generated
2. Key Derivation: The password and salt are combined and hashed multiple times
3. Cost Factor: The number of iterations (2^rounds) determines computational cost
4. Output: A single string containing algorithm, cost, salt, and hash

Bcrypt Hash Format

A bcrypt hash looks like this: $2a$10$N9qo8uLOickgx2ZMRZoMyeIjZAgcfl7p92ldGxad68LJZdL17lhWy

• $2a$ - Bcrypt algorithm identifier
• 10$ - Cost factor (2^10 = 1,024 iterations)
• Next 22 chars - Base64-encoded salt
• Remaining chars - Base64-encoded hash

Choosing the Right Cost Factor

The cost factor (rounds) determines how many iterations bcrypt performs. Higher values are more secure but slower:

• 4-6 rounds: Fast, suitable for testing only
• 10 rounds: Recommended for most applications (default)
• 12-13 rounds: High security for sensitive data
• 14-15 rounds: Maximum security, noticeably slow

Best Practices

• Use at least 10 rounds for production systems
• Never store passwords in plain text
• Always use bcrypt's built-in salt generation
• Increase rounds as hardware improves over time
• Use bcrypt for password storage, not for general hashing
• Implement rate limiting on login attempts

Common Use Cases

• User authentication systems
• Password storage in databases
• API key hashing
• Secure credential management
• Multi-factor authentication systems

Bcrypt vs Other Algorithms

Security Considerations

While bcrypt is highly secure, remember these important points:

• Bcrypt has a maximum password length of 72 bytes
• Always use HTTPS when transmitting passwords
• Implement account lockout after failed attempts
• Consider using Argon2 for new projects (more modern)
• Regularly update your bcrypt library