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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
+ * 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;
+}
+
+/**
+ * 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);
+}