protected function PhpassHashedPassword::crypt

protected PhpassHashedPassword::crypt($algo, $password, $setting)

Hash a password using a secure stretched hash.

By using a salt and repeated hashing the password is "stretched". Its security is increased because it becomes much more computationally costly for an attacker to try to break the hash by brute-force computation of the hashes of a large number of plain-text words or strings to find a match.

Parameters

string $algo: The string name of a hashing algorithm usable by hash(), like 'sha256'.

string $password: Plain-text password up to 512 bytes (128 to 512 UTF-8 characters) to hash.

string $setting: An existing hash or the output of $this->generateSalt(). Must be at least 12 characters (the settings and salt).

Return value

string A string containing the hashed password (and salt) or FALSE on failure. The return string will be truncated at HASH_LENGTH characters max.

File

core/lib/Drupal/Core/Password/PhpassHashedPassword.php, line 155

Class

PhpassHashedPassword

Secure password hashing functions based on the Portable PHP password hashing framework.

Namespace

Drupal\Core\Password

Code

protected function crypt($algo, $password, $setting) {
  // Prevent DoS attacks by refusing to hash large passwords.
  if (strlen($password) > PasswordInterface::PASSWORD_MAX_LENGTH) {
    return FALSE;
  }

  // The first 12 characters of an existing hash are its setting string.
  $setting = substr($setting, 0, 12);

  if ($setting[0] != '$' || $setting[2] != '$') {
    return FALSE;
  }
  $count_log2 = $this->getCountLog2($setting);
  // Stored hashes may have been crypted with any iteration count. However we
  // do not allow applying the algorithm for unreasonable low and high values
  // respectively.
  if ($count_log2 != $this->enforceLog2Boundaries($count_log2)) {
    return FALSE;
  }
  $salt = substr($setting, 4, 8);
  // Hashes must have an 8 character salt.
  if (strlen($salt) != 8) {
    return FALSE;
  }

  // Convert the base 2 logarithm into an integer.
  $count = 1 << $count_log2;

  // We rely on the hash() function being available in PHP 5.2+.
  $hash = hash($algo, $salt . $password, TRUE);
  do {
    $hash = hash($algo, $hash . $password, TRUE);
  } while (--$count);

  $len = strlen($hash);
  $output = $setting . $this->base64Encode($hash, $len);
  // $this->base64Encode() of a 16 byte MD5 will always be 22 characters.
  // $this->base64Encode() of a 64 byte sha512 will always be 86 characters.
  $expected = 12 + ceil((8 * $len) / 6);
  return (strlen($output) == $expected) ? substr($output, 0, static::HASH_LENGTH) : FALSE;
}