/** * 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. * * @param $algo * The string name of a hashing algorithm usable by hash(), like 'sha256'. * @param $password * The plain-text password to hash. * @param $setting * An existing hash or the output of _password_generate_salt(). Must be * at least 12 characters (the settings and salt). * * @return * A string containing the hashed password (and salt) or FALSE on failure. * The return string will be truncated at DRUPAL_HASH_LENGTH characters max. */ function _password_crypt($algo, $password, $setting) { // The first 12 characters of an existing hash are its setting string. $setting = substr($setting, 0, 12); if ($setting[0] != '$' || $setting[2] != '$') { return FALSE; } $count_log2 = _password_get_count_log2($setting); // Hashes may be imported from elsewhere, so we allow != DRUPAL_HASH_COUNT if ($count_log2 < DRUPAL_MIN_HASH_COUNT || $count_log2 > DRUPAL_MAX_HASH_COUNT) { 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 = $setting . _password_base64_encode($hash, $len); // _password_base64_encode() of a 16 byte MD5 will always be 22 characters. // _password_base64_encode() of a 64 byte sha512 will always be 86 characters. $expected = 12 + ceil(8 * $len / 6); return strlen($output) == $expected ? substr($output, 0, DRUPAL_HASH_LENGTH) : FALSE; }
/** * Check whether a user's hashed password needs to be replaced with a new hash. * * This is typically called during the login process when the plain text * password is available. A new hash is needed when the desired iteration count * has changed through a change in the variable password_count_log2 or * DRUPAL_HASH_COUNT or if the user's password hash was generated in an update * like user_update_7000(). * * Alternative implementations of this function might use other criteria based * on the fields in $account. * * @param $account * A user object with at least the fields from the {users} table. * * @return * TRUE or FALSE. */ function user_needs_new_hash($account) { // Check whether this was an updated password. if (substr($account->pass, 0, 3) != '$P$' || strlen($account->pass) != 34) { return TRUE; } // Check whether the iteration count used differs from the standard number. return _password_get_count_log2($account->pass) != variable_get('password_count_log2', DRUPAL_HASH_COUNT); }