Rails Secret Key Generator

Rails uses secret_key_base for encrypting cookies, generating signed and encrypted messages, and verifying the integrity of signed cookies. It's a critical security configuration for any Rails application.

What is Rails SECRET_KEY_BASE?

The secret_key_base in Rails is a 128-character hexadecimal string used as the foundation for the application's key derivation. Rails derives specific keys for different purposes (encryption, signing) from this base key using HKDF.

Key Requirements

• 128 hexadecimal characters (64 bytes)
• Must be kept secret and secure
• Should be unique per application and environment
• Used for cookie encryption, signed messages, and Active Record encryption

How to Use

In Rails 5.2+, use encrypted credentials:
```bash
RAILS_MASTER_KEY=your_key rails credentials:edit
```

Or set as an environment variable:
```bash
export SECRET_KEY_BASE=your_generated_key_here
```

Generate with Rails:
```bash
rails secret
```

Best Practices

• Use Rails credentials (encrypted) for storing secrets
• Keep master.key out of version control
• Use different keys for each environment
• Consider using Rails 7's per-environment credentials
• Back up your master.key securely

Common Mistakes to Avoid

• ✗Committing master.key to version control
• ✗Using the same secret_key_base across environments
• ✗Not setting the key in production (falls back to insecure defaults)
• ✗Losing the master.key (credentials become unreadable)