How Can I Securely Hash and Salt Passwords in PHP?

Securing PHP Passwords with Hashing and Salt

Hashing and salting are essential mechanisms for protecting user passwords in PHP applications. This article provides a comprehensive overview of these techniques, including recommendations on the best practices and considerations.

Why Hash Passwords?

Password hashing prevents malicious actors from accessing user accounts by compromising the database. By using a one-way hashing algorithm, such as bcrypt or scrypt, the plain-text password is transformed into a large and irreversible digest, making it computationally infeasible to retrieve the original password.

Best Practices: Bcrypt or Scrypt

• Bcrypt: A robust hashing algorithm with adjustable cost parameters to ensure future security.
• Scrypt: A newer and even more secure alternative to bcrypt, but requires third-party extensions.

Average Practices: PBKDF2

If bcrypt or scrypt are not available, use PBKDF2 (Password-Based Key Derivation Function 2) with SHA2 hashes. Ensure a high number of rounds (e.g., 2500) for maximum security.

Why Use Salt?

Salting adds randomly generated data to the password before hashing. This ensures that identical passwords result in unique hashes, making it harder for attackers to perform precomputed rainbow table attacks.

Choosing a Good Salt

• Use a secure random number generator to generate unique salts.
• Store the salt alongside the hashed password in the database.
• Ensure the salt is of sufficient length and entropy.

Avoiding Common Pitfalls

• Never store plain-text passwords in the database.
• Don't rely on MD5 or SHA1 hashing algorithms.
• Enforce reasonable password complexity requirements without sacrificing entropy.
• Reset all passwords in case of a database compromise.

Conclusion

By following these best practices for password hashing and salting in PHP, you can significantly enhance the security of your user accounts and protect your application from malicious attacks.

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