Bcrypt Generator

How to use this bcrypt generator

1. Type the password you want to hash. Spaces and Unicode are kept exactly as typed.
2. Choose a cost. The default of 12 matches PHP 8.4 and newer. The label shows how long one hash took in your browser, which is a rough guide to your server.
3. Press Generate. Copy the hash into a database seed, a test fixture or a config file. Every press gives a new hash because the salt is random.
4. To check a hash, paste it on the right with a password. You get a clear match or no-match answer, just like password_verify().

Anatomy of a bcrypt hash

A bcrypt hash is always 60 characters and carries everything needed to verify it later. Take $2y$12$R9h/cIPz0gi.URNNX3kh2OPST9/PgBkqquzi.Ss7KIUgO2t0jWMUW:

• $2y$ is the algorithm identifier: bcrypt, with PHP's name for the fixed version.
• 12$ is the cost. The algorithm runs 2¹² = 4,096 rounds of its expensive key setup.
• The next 22 characters are the salt, encoded in bcrypt's own base64 alphabet.
• The last 31 characters are the hash itself.

Because salt and cost live inside the string, you store the whole hash in one column, usually VARCHAR(255) so a future algorithm with longer output still fits.

Hashing passwords in PHP

PHP has had a complete password API since 5.5. You never need to call crypt() or build salts yourself:

$hash = password_hash($password, PASSWORD_DEFAULT);

if (password_verify($input, $hash)) {
    // correct password
    if (password_needs_rehash($hash, PASSWORD_DEFAULT)) {
        $hash = password_hash($input, PASSWORD_DEFAULT); // store the upgraded hash
    }
}

PASSWORD_DEFAULT is bcrypt today, and PHP may switch it to a stronger algorithm in a future release, which is why the column should be wider than 60 characters. password_needs_rehash() lets you raise the cost over time: when a user logs in successfully, rehash with the new settings and save it. To set the cost explicitly, pass ['cost' => 12] as the third argument. You can try these functions directly in the PHP Sandbox.

Bcrypt or Argon2?

Both are good choices and far better than MD5, SHA-1 or plain SHA-256, which are fast by design and therefore easy to brute-force. Argon2id, available in PHP as PASSWORD_ARGON2ID when PHP is built with libargon2 or libsodium, is memory-hard, which makes attacks with graphics cards more expensive. Bcrypt is supported everywhere, is the PHP default and remains a safe choice when the cost is set sensibly. Moving from one to the other is easy, since password_verify() understands both and password_needs_rehash() tells you when to upgrade.

Common problems

• Verify always fails: the hash was cut off. Check that the database column holds all 60 characters and that no framework trimmed or escaped the $ signs. In .env files and shell commands, wrap the hash in single quotes.
• Hash from another language does not verify: make sure it is really bcrypt and starts with $2. Hashes from Node's bcrypt ($2b$) work in PHP without changes.
• Logins are slow: the cost is too high for your server. Lower it by one and let password_needs_rehash() migrate users as they log in.