Here's the implementation for the authentication system:

To use this code:

1. Set up your MySQL database with a users table containing columns for id, name, email, and password.
2. Add these dependencies to your app's build.gradle:

3. Add internet permission to your AndroidManifest.xml:

4. Create the necessary drawable resources (rounded_button.xml, ic_back.xml).
5. Update the database connection details in DatabaseHelper.java with your MySQL server information.

This implementation includes:

• Secure password hashing (implement hashPassword method)
• Input validation
• Async database operations
• Custom UI components
• Navigation between screens
• OTP verification logic

Remember to:

• Handle configuration changes
• Implement proper error handling
• Add loading indicators for network operations
• Implement proper security measures for storing sensitive data
• Consider using HTTPS for API communications
• Implement proper session management