Writing a robust password validation function requires careful consideration of various factors to ensure its effectiveness. Here are some steps to follow when writing a password validation function:
1. Determine the minimum password length: This refers to the number of characters that a password must have to be accepted. A good rule of thumb is to set a minimum length of at least 8 characters.
2. Use a combination of characters: Passwords should consist of a mixture of upper and lowercase letters, numbers, and special characters.
3. Enforce complexity rules: Require passwords to have at least one uppercase letter, one lowercase letter, one number, and one special character.
4. Avoid common passwords and patterns: Avoid allowing simple passwords like "password123" or "qwerty" by checking against a list of known common passwords. Also, avoid common patterns like "123456" or "abcd1234."
5. Limit login attempts: Set limits to the number of login attempts a user can make before being locked out. This prevents brute-force attacks.
6. Hash and salt passwords: Store passwords as salted hashes to prevent attackers from accessing user's passwords even if they manage to access the database.
By following these steps, you can craft a password validation function that minimizes the risk of security breaches and keeps your users' accounts secure.