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- <?php
- /**
- * @file
- * Secure password hashing functions for user authentication.
- *
- * Based on the Portable PHP password hashing framework.
- * @see http://www.openwall.com/phpass/
- *
- * An alternative or custom version of this password hashing API may be
- * used by setting the variable password_inc to the name of the PHP file
- * containing replacement user_hash_password(), user_check_password(), and
- * user_needs_new_hash() functions.
- */
- /**
- * The standard log2 number of iterations for password stretching. This should
- * increase by 1 every Drupal version in order to counteract increases in the
- * speed and power of computers available to crack the hashes.
- */
- define('DRUPAL_HASH_COUNT', 15);
- /**
- * The minimum allowed log2 number of iterations for password stretching.
- */
- define('DRUPAL_MIN_HASH_COUNT', 7);
- /**
- * The maximum allowed log2 number of iterations for password stretching.
- */
- define('DRUPAL_MAX_HASH_COUNT', 30);
- /**
- * The expected (and maximum) number of characters in a hashed password.
- */
- define('DRUPAL_HASH_LENGTH', 55);
- /**
- * Returns a string for mapping an int to the corresponding base 64 character.
- */
- function _password_itoa64() {
- return './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
- }
- /**
- * Encodes bytes into printable base 64 using the *nix standard from crypt().
- *
- * @param $input
- * The string containing bytes to encode.
- * @param $count
- * The number of characters (bytes) to encode.
- *
- * @return
- * Encoded string
- */
- function _password_base64_encode($input, $count) {
- $output = '';
- $i = 0;
- $itoa64 = _password_itoa64();
- do {
- $value = ord($input[$i++]);
- $output .= $itoa64[$value & 0x3f];
- if ($i < $count) {
- $value |= ord($input[$i]) << 8;
- }
- $output .= $itoa64[($value >> 6) & 0x3f];
- if ($i++ >= $count) {
- break;
- }
- if ($i < $count) {
- $value |= ord($input[$i]) << 16;
- }
- $output .= $itoa64[($value >> 12) & 0x3f];
- if ($i++ >= $count) {
- break;
- }
- $output .= $itoa64[($value >> 18) & 0x3f];
- } while ($i < $count);
- return $output;
- }
- /**
- * Generates a random base 64-encoded salt prefixed with settings for the hash.
- *
- * Proper use of salts may defeat a number of attacks, including:
- * - The ability to try candidate passwords against multiple hashes at once.
- * - The ability to use pre-hashed lists of candidate passwords.
- * - The ability to determine whether two users have the same (or different)
- * password without actually having to guess one of the passwords.
- *
- * @param $count_log2
- * Integer that determines the number of iterations used in the hashing
- * process. A larger value is more secure, but takes more time to complete.
- *
- * @return
- * A 12 character string containing the iteration count and a random salt.
- */
- function _password_generate_salt($count_log2) {
- $output = '$S$';
- // Ensure that $count_log2 is within set bounds.
- $count_log2 = _password_enforce_log2_boundaries($count_log2);
- // We encode the final log2 iteration count in base 64.
- $itoa64 = _password_itoa64();
- $output .= $itoa64[$count_log2];
- // 6 bytes is the standard salt for a portable phpass hash.
- $output .= _password_base64_encode(drupal_random_bytes(6), 6);
- return $output;
- }
- /**
- * Ensures that $count_log2 is within set bounds.
- *
- * @param $count_log2
- * Integer that determines the number of iterations used in the hashing
- * process. A larger value is more secure, but takes more time to complete.
- *
- * @return
- * Integer within set bounds that is closest to $count_log2.
- */
- function _password_enforce_log2_boundaries($count_log2) {
- if ($count_log2 < DRUPAL_MIN_HASH_COUNT) {
- return DRUPAL_MIN_HASH_COUNT;
- }
- elseif ($count_log2 > DRUPAL_MAX_HASH_COUNT) {
- return DRUPAL_MAX_HASH_COUNT;
- }
- return (int) $count_log2;
- }
- /**
- * 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
- * Plain-text password up to 512 bytes (128 to 512 UTF-8 characters) 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, $setting) {
- // Prevent DoS attacks by refusing to hash large passwords.
- if (strlen($password) > 512) {
- 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;
- }
- $count_log2 = _password_get_count_log2($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;
- }
- /**
- * Parse the log2 iteration count from a stored hash or setting string.
- */
- function _password_get_count_log2($setting) {
- $itoa64 = _password_itoa64();
- return strpos($itoa64, $setting[3]);
- }
- /**
- * Hash a password using a secure hash.
- *
- * @param $password
- * A plain-text password.
- * @param $count_log2
- * Optional integer to specify the iteration count. Generally used only during
- * mass operations where a value less than the default is needed for speed.
- *
- * @return
- * A string containing the hashed password (and a salt), or FALSE on failure.
- */
- function user_hash_password($password, $count_log2 = 0) {
- if (empty($count_log2)) {
- // Use the standard iteration count.
- $count_log2 = variable_get('password_count_log2', DRUPAL_HASH_COUNT);
- }
- return _password_crypt('sha512', $password, _password_generate_salt($count_log2));
- }
- /**
- * Check whether a plain text password matches a stored hashed password.
- *
- * Alternative implementations of this function may use other data in the
- * $account object, for example the uid to look up the hash in a custom table
- * or remote database.
- *
- * @param $password
- * A plain-text password
- * @param $account
- * A user object with at least the fields from the {users} table.
- *
- * @return
- * TRUE or FALSE.
- */
- function user_check_password($password, $account) {
- if (substr($account->pass, 0, 2) == 'U$') {
- // This may be an updated password from user_update_7000(). Such hashes
- // have 'U' added as the first character and need an extra md5().
- $stored_hash = substr($account->pass, 1);
- $password = md5($password);
- }
- else {
- $stored_hash = $account->pass;
- }
- $type = substr($stored_hash, 0, 3);
- switch ($type) {
- case '$S$':
- // A normal Drupal 7 password using sha512.
- $hash = _password_crypt('sha512', $password, $stored_hash);
- break;
- case '$H$':
- // phpBB3 uses "$H$" for the same thing as "$P$".
- case '$P$':
- // A phpass password generated using md5. This is an
- // imported password or from an earlier Drupal version.
- $hash = _password_crypt('md5', $password, $stored_hash);
- break;
- default:
- return FALSE;
- }
- return ($hash && $stored_hash == $hash);
- }
- /**
- * 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($account->pass, 0, 3) != '$S$') || (strlen($account->pass) != DRUPAL_HASH_LENGTH)) {
- return TRUE;
- }
- // Ensure that $count_log2 is within set bounds.
- $count_log2 = _password_enforce_log2_boundaries(variable_get('password_count_log2', DRUPAL_HASH_COUNT));
- // Check whether the iteration count used differs from the standard number.
- return (_password_get_count_log2($account->pass) !== $count_log2);
- }
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