This question already has answers here: 开发者_StackOverflow中文版 How to use PHP's password_hash to hash and verify passwords (5 answers) Closed 8 months ago.

Every now and then I hear the advice "Use bcrypt for storing passwords in PHP, bcrypt rules".

But what is bcrypt? PHP doesn't offer any such functions, Wikipedia babbles about a file-encryption utility and Web searches just reveal a few implementations of Blowfish in different languages. Now Blowfish is also available in PHP via mcrypt, but how does that help with storing passwords? Blowfish is a general purpose cipher, it works two ways. If it could be encrypted, it can be decrypted. Passwords need a one-way hashing function.

What is the explanation?

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bcrypt is a hashing algorithm which is scalable with hardware (via a configurable number of rounds). Its slowness and multiple rounds ensures that an attacker must deploy massive funds and hardware to be able to crack your passwords. Add to that per-password salts (bcrypt REQUIRES salts) and you can be sure that an attack is virtually unfeasible without either ludicrous amount of funds or hardware.

bcrypt uses the Eksblowfish algorithm to hash passwords. While the encryption phase of Eksblowfish and Blowfish are exactly the same, the key schedule phase of Eksblowfish ensures that any subsequent state depends on both salt and key (user password), and no state can be precomputed without the knowledge of both. Because of this key difference, bcrypt is a one-way hashing algorithm. You cannot retrieve the plain text password without already knowing the salt, rounds and key (password). [Source]

How to use bcrypt:

Using PHP >= 5.5-DEV

Password hashing functions have now been built directly into PHP >= 5.5. You may now use password_hash() to create a bcrypt hash of any password:

<?php
// Usage 1:
echo password_hash('rasmuslerdorf', PASSWORD_DEFAULT)."\n";
// $2y$10$xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
// For example:
// $2y$10$.vGA1O9wmRjrwAVXD98HNOgsNpDczlqm3Jq7KnEd1rVAGv3Fykk1a

// Usage 2:
$options = [
  'cost' => 11
];
echo password_hash('rasmuslerdorf', PASSWORD_BCRYPT, $options)."\n";
// $2y$11$6DP.V0nO7YI3iSki4qog6OQI5eiO6Jnjsqg7vdnb.JgGIsxniOn4C

To verify a user provided password against an existing hash, you may use the password_verify() as such:

<?php
// See the password_hash() example to see where this came from.
$hash = '$2y$07$BCryptRequires22Chrcte/VlQH0piJtjXl.0t1XkA8pw9dMXTpOq';

if (password_verify('rasmuslerdorf', $hash)) {
    echo 'Password is valid!';
} else {
    echo 'Invalid password.';
}

Using PHP >= 5.3.7, < 5.5-DEV (also RedHat PHP >= 5.3.3)

There is a compatibility library on GitHub created based on the source code of the above functions originally written in C, which provides the same functionality. Once the compatibility library is installed, usage is the same as above (minus the shorthand array notation if you are still on the 5.3.x branch).

Using PHP < 5.3.7 (DEPRECATED)

You can use crypt() function to generate bcrypt hashes of input strings. This class can automatically generate salts and verify existing hashes against an input. If you are using a version of PHP higher or equal to 5.3.7, it is highly recommended you use the built-in function or the compat library. This alternative is provided only for historical purposes.

class Bcrypt{
  private $rounds;

  public function __construct($rounds = 12) {
    if (CRYPT_BLOWFISH != 1) {
      throw new Exception("bcrypt not supported in this installation. See http://php.net/crypt");
    }

    $this->rounds = $rounds;
  }

  public function hash($input){
    $hash = crypt($input, $this->getSalt());

    if (strlen($hash) > 13)
      return $hash;

    return false;
  }

  public function verify($input, $existingHash){
    $hash = crypt($input, $existingHash);

    return $hash === $existingHash;
  }

  private function getSalt(){
    $salt = sprintf('$2a$%02d$', $this->rounds);

    $bytes = $this->getRandomBytes(16);

    $salt .= $this->encodeBytes($bytes);

    return $salt;
  }

  private $randomState;
  private function getRandomBytes($count){
    $bytes = '';

    if (function_exists('openssl_random_pseudo_bytes') &&
        (strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN')) { // OpenSSL is slow on Windows
      $bytes = openssl_random_pseudo_bytes($count);
    }

    if ($bytes === '' && is_readable('/dev/urandom') &&
       ($hRand = @fopen('/dev/urandom', 'rb')) !== FALSE) {
      $bytes = fread($hRand, $count);
      fclose($hRand);
    }

    if (strlen($bytes) < $count) {
      $bytes = '';

      if ($this->randomState === null) {
        $this->randomState = microtime();
        if (function_exists('getmypid')) {
          $this->randomState .= getmypid();
        }
      }

      for ($i = 0; $i < $count; $i += 16) {
        $this->randomState = md5(microtime() . $this->randomState);

        if (PHP_VERSION >= '5') {
          $bytes .= md5($this->randomState, true);
        } else {
          $bytes .= pack('H*', md5($this->randomState));
        }
      }

      $bytes = substr($bytes, 0, $count);
    }

    return $bytes;
  }

  private function encodeBytes($input){
    // The following is code from the PHP Password Hashing Framework
    $itoa64 = './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';

    $output = '';
    $i = 0;
    do {
      $c1 = ord($input[$i++]);
      $output .= $itoa64[$c1 >> 2];
      $c1 = ($c1 & 0x03) << 4;
      if ($i >= 16) {
        $output .= $itoa64[$c1];
        break;
      }

      $c2 = ord($input[$i++]);
      $c1 |= $c2 >> 4;
      $output .= $itoa64[$c1];
      $c1 = ($c2 & 0x0f) << 2;

      $c2 = ord($input[$i++]);
      $c1 |= $c2 >> 6;
      $output .= $itoa64[$c1];
      $output .= $itoa64[$c2 & 0x3f];
    } while (true);

    return $output;
  }
}

You can use this code like this:

$bcrypt = new Bcrypt(15);

$hash = $bcrypt->hash('password');
$isGood = $bcrypt->verify('password', $hash);

Alternatively, you may also use the Portable PHP Hashing Framework.

---

So, you want to use bcrypt? Awesome! However, like other areas of cryptography, you shouldn't be doing it yourself. If you need to worry about anything like managing keys, or storing salts or generating random numbers, you're doing it wrong.

The reason is simple: it's so trivially easy to screw up bcrypt. In fact, if you look at almost every piece of code on this page, you'll notice that it's violating at least one of these common problems.

Face It, Cryptography is hard.

Leave it for the experts. Leave it for people whose job it is to maintain these libraries. If you need to make a decision, you're doing it wrong.

Instead, just use a library. Several exist depending on your requirements.

Libraries

Here is a breakdown of some of the more common APIs.

PHP 5.5 API - (Available for 5.3.7+)

Starting in PHP 5.5, a new API for hashing passwords is being introduced. There is also a shim compatibility library maintained (by me) for 5.3.7+. This has the benefit of being a peer-reviewed and simple to use implementation.

function register($username, $password) {
    $hash = password_hash($password, PASSWORD_BCRYPT);
    save($username, $hash);
}

function login($username, $password) {
    $hash = loadHashByUsername($username);
    if (password_verify($password, $hash)) {
        //login
    } else {
        // failure
    }
}

Really, it's aimed to be extremely simple.

Resources:

• Documentation: on PHP.net
• Compatibility Library: on GitHub
• PHP's RFC: on wiki.php.net

Zend\Crypt\Password\Bcrypt (5.3.2+)

This is another API that's similar to the PHP 5.5 one, and does a similar purpose.

function register($username, $password) {
    $bcrypt = new Zend\Crypt\Password\Bcrypt();
    $hash = $bcrypt->create($password);
    save($user, $hash);
}

function login($username, $password) {
    $hash = loadHashByUsername($username);
    $bcrypt = new Zend\Crypt\Password\Bcrypt();
    if ($bcrypt->verify($password, $hash)) {
        //login
    } else {
        // failure
    }
}

Resources:

• Documentation: on Zend
• Blog Post: Password Hashing With Zend Crypt

PasswordLib

This is a slightly different approach to password hashing. Rather than simply supporting bcrypt, PasswordLib supports a large number of hashing algorithms. It's mainly useful in contexts where you need to support compatibility with legacy and disparate systems that may be outside of your control. It supports a large number of hashing algorithms. And is supported 5.3.2+

function register($username, $password) {
    $lib = new PasswordLib\PasswordLib();
    $hash = $lib->createPasswordHash($password, '$2y$', array('cost' => 12));
    save($user, $hash);
}

function login($username, $password) {
    $hash = loadHashByUsername($username);
    $lib = new PasswordLib\PasswordLib();
    if ($lib->verifyPasswordHash($password, $hash)) {
        //login
    } else {
        // failure
    }
}

References:

• Source Code / Documentation: GitHub

PHPASS

This is a layer that does support bcrypt, but also supports a fairly strong algorithm that's useful if you do not have access to PHP >= 5.3.2... It actually supports PHP 3.0+ (although not with bcrypt).

function register($username, $password) {
    $phpass = new PasswordHash(12, false);
    $hash = $phpass->HashPassword($password);
    save($user, $hash);
}

function login($username, $password) {
    $hash = loadHashByUsername($username);
    $phpass = new PasswordHash(12, false);
    if ($phpass->CheckPassword($password, $hash)) {
        //login
    } else {
        // failure
    }
}

Resources

• Code: cvsweb
• Project Site: on OpenWall
• A review of the < 5.3.0 algorithm: on StackOverflow

Note: Don't use the PHPASS alternatives that are not hosted on openwall, they are different projects!!!

About BCrypt

If you notice, every one of these libraries returns a single string. That's because of how BCrypt works internally. And there are a TON of answers about that. Here are a selection that I've written, that I won't copy/paste here, but link to:

• Fundamental Difference Between Hashing And Encryption Algorithms - Explaining the terminology and some basic information about them.
• About reversing hashes without rainbow tables - Basically why we should use bcrypt in the first place...
• Storing bcrypt Hashes - basically why is the salt and algorithm included in the hash result.
• How to update the cost of bcrypt hashes - basically how to choose and then maintain the cost of the bcrypt hash.
• How to hash long passwords with bcrypt - explaining the 72 character password limit of bcrypt.
• How bcrypt uses salts
• Best practices of salting and peppering passwords - Basically, don't use a "pepper"
• Migrating old md5 passwords to bcrypt

Wrap Up

There are many different choices. Which you choose is up to you. However, I would HIGHLY recommend that you use one of the above libraries for handling this for you.

Again, if you're using crypt() directly, you're probably doing something wrong. If your code is using hash() (or md5() or sha1()) directly, you're almost definitely doing something wrong.

Just use a library...

---

You'll get a lot of information in Enough With The Rainbow Tables: What You Need To Know About Secure Password Schemes or Portable PHP password hashing framework.

The goal is to hash the password with something slow, so someone getting your password database will die trying to brute force it (a 10 ms delay to check a password is nothing for you, a lot for someone trying to brute force it). Bcrypt is slow and can be used with a parameter to choose how slow it is.

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You can create a one-way hash with bcrypt using PHP's crypt() function and passing in an appropriate Blowfish salt. The most important of the whole equation is that A) the algorithm hasn't been compromised and B) you properly salt each password. Don't use an application-wide salt; that opens up your entire application to attack from a single set of Rainbow tables.

PHP - Crypt Function

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---

Edit: 2013.01.15 - If your server will support it, use martinstoeckli's solution instead.

---

Everyone wants to make this more complicated than it is. The crypt() function does most of the work.

function blowfishCrypt($password,$cost)
{
    $chars='./ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    $salt=sprintf('$2y$%02d$',$cost);
//For PHP < PHP 5.3.7 use this instead
//    $salt=sprintf('$2a$%02d$',$cost);
    //Create a 22 character salt -edit- 2013.01.15 - replaced rand with mt_rand
    mt_srand();
    for($i=0;$i<22;$i++) $salt.=$chars[mt_rand(0,63)];
    return crypt($password,$salt);
}

Example:

$hash=blowfishCrypt('password',10); //This creates the hash
$hash=blowfishCrypt('password',12); //This creates a more secure hash
if(crypt('password',$hash)==$hash){ /*ok*/ } //This checks a password

I know it should be obvious, but please don't use 'password' as your password.

---

Version 5.5 of PHP will have built-in support for BCrypt, the functions password_hash() and password_verify(). Actually these are just wrappers around the function crypt(), and shall make it easier to use it correctly. It takes care of the generation of a safe random salt, and provides good default values.

The easiest way to use this functions will be:

$hashToStoreInDb = password_hash($password, PASSWORD_BCRYPT);
$isPasswordCorrect = password_verify($password, $existingHashFromDb);

This code will hash the password with BCrypt (algorithm 2y), generates a random salt from the OS random source, and uses the default cost parameter (at the moment this is 10). The second line checks, if the user entered password matches an already stored hash-value.

Should you want to change the cost parameter, you can do it like this, increasing the cost parameter by 1, doubles the needed time to calculate the hash value:

$hash = password_hash($password, PASSWORD_BCRYPT, array("cost" => 11));

In contrast to the "cost" parameter, it is best to omit the "salt" parameter, because the function already does its best to create a cryptographically safe salt.

For PHP version 5.3.7 and later, there exists a compatibility pack, from the same author that made the password_hash() function. For PHP versions before 5.3.7 there is no support for crypt() with 2y, the unicode safe BCrypt algorithm. One could replace it instead with 2a, which is the best alternative for earlier PHP versions.

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Current thinking: hashes should be the slowest available, not the fastest possible. This suppresses rainbow table attacks.

Also related, but precautionary: An attacker should never have unlimited access to your login screen. To prevent that: Set up an IP address tracking table that records every hit along with the URI. If more than 5 attempts to login come from the same IP address in any five minute period, block with explanation. A secondary approach is to have a two-tiered password scheme, like banks do. Putting a lock-out for failures on the second pass boosts security.

Summary: slow down the attacker by using time-consuming hash functions. Also, block on too many accesses to your login, and add a second password tier.

---

Here's an updated answer to this old question!

The right way to hash passwords in PHP since 5.5 is with password_hash(), and the right way to verify them is with password_verify(), and this is still true in PHP 8.0. These functions use bcrypt hashes by default, but other stronger algorithms have been added. You can alter the work factor (effectively how "strong" the encryption is) via the password_hash parameters.

However, while it's still plenty strong enough, bcrypt is no longer considered state-of-the-art; a better set of password hash algorithms has arrived called Argon2, with Argon2i, Argon2d, and Argon2id variants. The difference between them (as described here):

Argon2 has one primary variant: Argon2id, and two supplementary variants: Argon2d and Argon2i. Argon2d uses data-depending memory access, which makes it suitable for cryptocurrencies and proof-of-work applications with no threats from side-channel timing attacks. Argon2i uses data-independent memory access, which is preferred for password hashing and password-based key derivation. Argon2id works as Argon2i for the first half of the first iteration over the memory, and as Argon2d for the rest, thus providing both side-channel attack protection and brute-force cost savings due to time-memory tradeoffs.

Argon2i support was added in PHP 7.2, and you request it like this:

$hash = password_hash('mypassword', PASSWORD_ARGON2I);

and Argon2id support was added in PHP 7.3:

$hash = password_hash('mypassword', PASSWORD_ARGON2ID);

No changes are required for verifying passwords since the resulting hash string contains information about what algorithm, salt, and work factors were used when it was created.

Quite separately (and somewhat redundantly), libsodium (added in PHP 7.2) also provides Argon2 hashing via the sodium_crypto_pwhash_str () and sodium_crypto_pwhash_str_verify() functions, which work much the same way as the PHP built-ins. One possible reason for using these is that PHP may sometimes be compiled without libargon2, which makes the Argon2 algorithms unavailable to the password_hash function; PHP 7.2 and higher should always have libsodium enabled, but it may not - but at least there are two ways you can get at that algorithm. Here's how you can create an Argon2id hash with libsodium (even in PHP 7.2, which otherwise lacks Argon2id support)):

$hash = sodium_crypto_pwhash_str(
    'mypassword',
    SODIUM_CRYPTO_PWHASH_OPSLIMIT_INTERACTIVE,
    SODIUM_CRYPTO_PWHASH_MEMLIMIT_INTERACTIVE
);

Note that it doesn't allow you to specify a salt manually; this is part of libsodium's ethos – don't allow users to set params to values that might compromise security – for example there is nothing preventing you from passing an empty salt string to PHP's password_hash function; libsodium doesn't let you do anything so silly!

---

For OAuth 2 passwords:

$bcrypt = new \Zend\Crypt\Password\Bcrypt;
$bcrypt->create("youpasswordhere", 10)

---

As we all know storing password in clear text in database is not secure. the bcrypt is a hashing password technique.It is used to built password security. One of the amazing function of bcrypt is it save us from hackers it is used to protect the password from hacking attacks because the password is stored in bcrypted form.

The password_hash() function is used to create a new password hash. It uses a strong & robust hashing algorithm. The password_hash() function is very much compatible with the crypt() function. Therefore, password hashes created by crypt() may be used with password_hash() and vice-versa. The functions password_verify() and password_hash() just the wrappers around the function crypt(), and they make it much easier to use it accurately.

SYNTAX

string password_hash($password, $algo, $options)

The following algorithms are currently supported by password_hash() function:

• PASSWORD_DEFAULT
• PASSWORD_BCRYPT
• PASSWORD_ARGON2I
• PASSWORD_ARGON2ID

Parameters: This function accepts three parameters as mentioned above and described below:

$password: It stores the password of the user.

$algo: It is the password algorithm constant that is used continuously while denoting the algorithm which is to be used when the hashing of password takes place.

$options: It is an associative array, which contains the options. If this is removed and doesn’t include, a random salt is going to be used, and the utilization of a default cost will happen.

Return Value: It returns the hashed password on success or False on failure.

Example:

Input:

echo password_hash("GFG@123", PASSWORD_DEFAULT);

Output:

$2y$10$.vGA19Jh8YrwSJFDodbfoHJIOFH)DfhuofGv3Fykk1a

Below programs illustrate the password_hash() function in PHP:

<?php echo password_hash("GFG@123", PASSWORD_DEFAULT); ?>

OUTPUT

$2y$10$Z166W1fBdsLcXPVQVfPw/uRq1ueWMA6sLt9bmdUFz9AmOGLdM393G

---

The password_hash() function in PHP is a built-in function, used to create a new password hash with different algorithms and options. The function uses a strong hashing algorithm.

The function take 2 mandatory parameters: $password and $algorithm, and 1 optional parameter $options.

$strongPassword = password_hash( $password, $algorithm, $options );

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Algorithms allowed right now for password_hash() are:

• PASSWORD_DEFAULT
• PASSWORD_BCRYPT
• PASSWORD_ARGON2I
• PASSWORD_ARGON2ID

Example:

echo password_hash("abcDEF", PASSWORD_DEFAULT);

Answer:

$2y$10$KwKceUaG84WInAif5ehdZOkE4kHPWTLp0ZK5a5OU2EbtdwQ9YIcGy

Example:

echo password_hash("abcDEF", PASSWORD_BCRYPT);

Answer:

$2y$10$SNly5bFzB/R6OVbBMq1bj.yiOZdsk6Mwgqi4BLR2sqdCvMyv/AyL2

---

To use the BCRYPT, set option cost=12 in an $options, also change first parameter $password to some strong password like "wgt167yuWBGY@#1987__".

Example:

echo password_hash("wgt167yuWBGY@#1987__", PASSWORD_BCRYPT, ['cost' => 12]);

Answer:

$2y$12$TjSggXiFSidD63E.QP8PJOds2texJfsk/82VaNU8XRZ/niZhzkJ6S