cms/drupal/includes/password.inc
changeset 541 e756a8c72c3d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/includes/password.inc	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,291 @@
+<?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);
+}