PHP 加密：Password Hashing API

1. Introduction

Poor password storage is one of the major security vulnerabilities in web development. Storing passwords in plain text or using weak hashing algorithms can lead to devastating consequences if the passwords fall into the wrong hands. PHP provides a secure and easy-to-use solution for password hashing through the Password Hashing API.

2. Why Password Hashing is Important

Password hashing is the process of converting a password into a fixed-length string of characters that cannot be reversed. It adds an extra layer of security to prevent unauthorized access to user accounts. Without proper password hashing, passwords can be easily obtained by attackers and used for malicious purposes, such as impersonating users or gaining unauthorized access to their accounts.

Using weak hashing algorithms or storing passwords in plain text is a security risk that must be avoided.

3. PHP's Password Hashing API

The PHP Password Hashing API provides a simple and secure way to hash passwords using strong algorithms. It incorporates best practices for password storage and includes features like automatic salt generation and password verification.

Here's an example of how to hash a password using the Password Hashing API:

$password = "myPassword123";
$hashedPassword = password_hash($password, PASSWORD_DEFAULT);

In the code above, we use the password_hash() function to hash the password using the default algorithm (currently PASSWORD_DEFAULT). The resulting hashed password can then be stored in the database.

4. Verifying Passwords

When it comes to password authentication, we need a way to verify whether a provided password matches the stored hashed password. The Password Hashing API provides a password_verify() function for this purpose.

Here's an example of how to verify a password:

$hashedPasswordFromDatabase = "$2y$10$hOaMaeachjUQGXnsgvuzVe6Bu7vjmpH5zr2i/4rBsHESG5HSM2rOq";
$userInputPassword = "myPassword123";
if (password_verify($userInputPassword, $hashedPasswordFromDatabase)) {
    echo "Password is correct!";
} else {
    echo "Invalid password.";
}

We use the password_verify() function to compare the user's input password with the stored hashed password from the database. If they match, the password is correct.

5. Additional Password Hashing Options

5.1. Custom Salt

The Password Hashing API automatically generates a unique salt for each password and includes it in the hashed password. However, you can also provide your own custom salt for added security:

$options = [
    'salt' => 'mysalt123',
];
$hashedPassword = password_hash($password, PASSWORD_DEFAULT, $options);

By providing a custom salt in the options array, you ensure that the same password will have a different hashed representation if used by multiple users.

5.2. Cost Parameter

The cost parameter determines the computational cost of the hashing algorithm. The higher the cost, the more secure the hash, but also the more CPU-intensive it becomes. The default cost is 10, but you can increase it for added security:

$options = [
    'cost' => 12,
];
$hashedPassword = password_hash($password, PASSWORD_DEFAULT, $options);

Increasing the cost parameter adds an additional layer of security to protect against brute force attacks.

6. Conclusion

Proper password storage is crucial for ensuring the security of user accounts in web applications. The PHP Password Hashing API provides a straightforward and secure solution for hashing passwords using strong algorithms. By using this API and following best practices, developers can significantly improve the overall security of their applications.

Remember, never store passwords in plain text. Always use a secure password hashing algorithm.