How can developers ensure the compatibility and verification of password hashes, even if the algorithm used in password hashing changes in the future?

To ensure compatibility and verification of password hashes even if the hashing algorithm changes in the future, developers can store additional information in the hashed password string itself. This information can include the algorithm used, as well as any necessary parameters for verification. By including this metadata in the hashed password, developers can easily determine the algorithm used during verification and adapt accordingly. 

<?php

function createHash($password) {
    $algorithm = 'argon2i'; // or any other hashing algorithm
    $options = ['cost' => 12]; // or any other necessary parameters

    $hash = password_hash($password, PASSWORD_ARGON2I, $options);

    return $algorithm . ':' . json_encode($options) . ':' . $hash;
}

function verifyPassword($password, $hashedPassword) {
    $parts = explode(':', $hashedPassword);
    $algorithm = $parts[0];
    $options = json_decode($parts[1], true);
    $hash = $parts[2];

    return password_verify($password, $hash) && password_needs_rehash($hash, constant("PASSWORD_" . strtoupper($algorithm)), $options);
}

// Example usage
$password = 'secret';
$hashedPassword = createHash($password);

echo verifyPassword($password, $hashedPassword) ? 'Password verified' : 'Password verification failed';
?>

Keywords

password hashing compatibility verification algorithm change PHP functions

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