How should passwords be stored in PHP?

Summary

Use password_hash() (bcrypt by default, or Argon2id) and password_verify(), and call password_needs_rehash() on login to upgrade old hashes.

Longer Answer

These functions handle salt generation and embed algorithm and cost in the hash string. Never use md5, sha1 or unsalted hash(). Bcrypt truncates input at 72 bytes; Argon2id (PASSWORD_ARGON2ID) is memory-hard and recommended where available.

Code Example

<?php
$hash = password_hash($password, PASSWORD_ARGON2ID);

if (password_verify($input, $hash)) {
    if (password_needs_rehash($hash, PASSWORD_ARGON2ID)) {
        $hash = password_hash($input, PASSWORD_ARGON2ID);
        // save new hash
    }
}

Key Points

• password_hash($pw, PASSWORD_DEFAULT)
• password_verify() is timing-safe
• Rehash on login when cost/algorithm changes
• Never use fast hashes like MD5/SHA1 for passwords