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- <?php
- namespace Drupal\Core\Password;
- use Drupal\Component\Utility\Crypt;
- /**
- * Secure password hashing functions based on the Portable PHP password
- * hashing framework.
- *
- * @see http://www.openwall.com/phpass/
- */
- class PhpassHashedPassword implements PasswordInterface {
- /**
- * The minimum allowed log2 number of iterations for password stretching.
- */
- const MIN_HASH_COUNT = 7;
- /**
- * The maximum allowed log2 number of iterations for password stretching.
- */
- const MAX_HASH_COUNT = 30;
- /**
- * The expected (and maximum) number of characters in a hashed password.
- */
- const HASH_LENGTH = 55;
- /**
- * Returns a string for mapping an int to the corresponding base 64 character.
- *
- * @var string
- */
- public static $ITOA64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
- /**
- * Specifies the number of times the hashing function will be applied when
- * generating new password hashes. The number of times is calculated by
- * raising 2 to the power of the given value.
- */
- protected $countLog2;
- /**
- * Constructs a new password hashing instance.
- *
- * @param int $countLog2
- * Password stretching iteration count. Specifies the number of times the
- * hashing function will be applied when generating new password hashes.
- * The number of times is calculated by raising 2 to the power of the given
- * value.
- */
- public function __construct($countLog2) {
- // Ensure that $countLog2 is within set bounds.
- $this->countLog2 = $this->enforceLog2Boundaries($countLog2);
- }
- /**
- * Encodes bytes into printable base 64 using the *nix standard from crypt().
- *
- * @param string $input
- * The string containing bytes to encode.
- * @param int $count
- * The number of characters (bytes) to encode.
- *
- * @return string
- * Encoded string.
- */
- protected function base64Encode($input, $count) {
- $output = '';
- $i = 0;
- do {
- $value = ord($input[$i++]);
- $output .= static::$ITOA64[$value & 0x3f];
- if ($i < $count) {
- $value |= ord($input[$i]) << 8;
- }
- $output .= static::$ITOA64[($value >> 6) & 0x3f];
- if ($i++ >= $count) {
- break;
- }
- if ($i < $count) {
- $value |= ord($input[$i]) << 16;
- }
- $output .= static::$ITOA64[($value >> 12) & 0x3f];
- if ($i++ >= $count) {
- break;
- }
- $output .= static::$ITOA64[($value >> 18) & 0x3f];
- } while ($i < $count);
- return $output;
- }
- /**
- * Generates a random base 64-encoded salt prefixed with hash settings.
- *
- * 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.
- *
- * @return string
- * A 12 character string containing the iteration count and a random salt.
- */
- protected function generateSalt() {
- $output = '$S$';
- // We encode the final log2 iteration count in base 64.
- $output .= static::$ITOA64[$this->countLog2];
- // 6 bytes is the standard salt for a portable phpass hash.
- $output .= $this->base64Encode(Crypt::randomBytes(6), 6);
- return $output;
- }
- /**
- * Ensures that $count_log2 is within set bounds.
- *
- * @param int $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 int
- * Integer within set bounds that is closest to $count_log2.
- */
- protected function enforceLog2Boundaries($count_log2) {
- if ($count_log2 < static::MIN_HASH_COUNT) {
- return static::MIN_HASH_COUNT;
- }
- elseif ($count_log2 > static::MAX_HASH_COUNT) {
- return static::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 string $algo
- * The string name of a hashing algorithm usable by hash(), like 'sha256'.
- * @param string $password
- * Plain-text password up to 512 bytes (128 to 512 UTF-8 characters) to
- * hash.
- * @param string $setting
- * An existing hash or the output of $this->generateSalt(). Must be at least
- * 12 characters (the settings and salt).
- *
- * @return string
- * A string containing the hashed password (and salt) or FALSE on failure.
- * The return string will be truncated at HASH_LENGTH characters max.
- */
- protected function crypt($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;
- }
- /**
- * Parses the log2 iteration count from a stored hash or setting string.
- *
- * @param string $setting
- * An existing hash or the output of $this->generateSalt(). Must be at least
- * 12 characters (the settings and salt).
- *
- * @return int
- * The log2 iteration count.
- */
- public function getCountLog2($setting) {
- return strpos(static::$ITOA64, $setting[3]);
- }
- /**
- * {@inheritdoc}
- */
- public function hash($password) {
- return $this->crypt('sha512', $password, $this->generateSalt());
- }
- /**
- * {@inheritdoc}
- */
- public function check($password, $hash) {
- if (substr($hash, 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() (see the
- // Drupal 7 documentation).
- $stored_hash = substr($hash, 1);
- $password = md5($password);
- }
- else {
- $stored_hash = $hash;
- }
- $type = substr($stored_hash, 0, 3);
- switch ($type) {
- case '$S$':
- // A normal Drupal 7 password using sha512.
- $computed_hash = $this->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.
- $computed_hash = $this->crypt('md5', $password, $stored_hash);
- break;
- default:
- return FALSE;
- }
- // Compare using hashEquals() instead of === to mitigate timing attacks.
- return $computed_hash && Crypt::hashEquals($stored_hash, $computed_hash);
- }
- /**
- * {@inheritdoc}
- */
- public function needsRehash($hash) {
- // Check whether this was an updated password.
- if ((substr($hash, 0, 3) != '$S$') || (strlen($hash) != static::HASH_LENGTH)) {
- return TRUE;
- }
- // Ensure that $count_log2 is within set bounds.
- $count_log2 = $this->enforceLog2Boundaries($this->countLog2);
- // Check whether the iteration count used differs from the standard number.
- return ($this->getCountLog2($hash) !== $count_log2);
- }
- }
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