<?php

namespace SilverStripe\Security;

/**
 * Blowfish encryption - this is the default from SilverStripe 3.
 * PHP 5.3+ will provide a php implementation if there is no system
 * version available.
 */
class PasswordEncryptor_Blowfish extends PasswordEncryptor
{
	/**
	 * Cost of encryption.
	 * Higher costs will increase security, but also increase server load.
	 * If you are using basic auth, you may need to decrease this as encryption
	 * will be run on every request.
	 * The two digit cost parameter is the base-2 logarithm of the iteration
	 * count for the underlying Blowfish-based hashing algorithmeter and must
	 * be in range 04-31, values outside this range will cause crypt() to fail.
	 */
	protected static $cost = 10;

	/**
	 * Sets the cost of the blowfish algorithm.
	 * See {@link PasswordEncryptor_Blowfish::$cost}
	 * Cost is set as an integer but
	 * Ensure that set values are from 4-31
	 *
	 * @param int $cost range 4-31
	 */
	public static function set_cost($cost)
	{
		self::$cost = max(min(31, $cost), 4);
	}

	/**
	 * Gets the cost that is set for the blowfish algorithm
	 *
	 * @return int
	 */
	public static function get_cost()
	{
		return self::$cost;
	}

	public function encrypt($password, $salt = null, $member = null)
	{
		// See: http://nz.php.net/security/crypt_blowfish.php
		// There are three version of the algorithm - y, a and x, in order
		// of decreasing security. Attempt to use the strongest version.
		$encryptedPassword = $this->encryptY($password, $salt);
		if (!$encryptedPassword) {
			$encryptedPassword = $this->encryptA($password, $salt);
		}
		if (!$encryptedPassword) {
			$encryptedPassword = $this->encryptX($password, $salt);
		}

		// We *never* want to generate blank passwords. If something
		// goes wrong, throw an exception.
		if (strpos($encryptedPassword, '$2') === false) {
			throw new PasswordEncryptor_EncryptionFailed('Blowfish password encryption failed.');
		}

		return $encryptedPassword;
	}

	public function encryptX($password, $salt)
	{
		$methodAndSalt = '$2x$' . $salt;
		$encryptedPassword = crypt($password, $methodAndSalt);

		if (strpos($encryptedPassword, '$2x$') === 0) {
			return $encryptedPassword;
		}

		// Check if system a is actually x, and if available, use that.
		if ($this->checkAEncryptionLevel() == 'x') {
			$methodAndSalt = '$2a$' . $salt;
			$encryptedPassword = crypt($password, $methodAndSalt);

			if (strpos($encryptedPassword, '$2a$') === 0) {
				$encryptedPassword = '$2x$' . substr($encryptedPassword, strlen('$2a$'));
				return $encryptedPassword;
			}
		}

		return false;
	}

	public function encryptY($password, $salt)
	{
		$methodAndSalt = '$2y$' . $salt;
		$encryptedPassword = crypt($password, $methodAndSalt);

		if (strpos($encryptedPassword, '$2y$') === 0) {
			return $encryptedPassword;
		}

		// Check if system a is actually y, and if available, use that.
		if ($this->checkAEncryptionLevel() == 'y') {
			$methodAndSalt = '$2a$' . $salt;
			$encryptedPassword = crypt($password, $methodAndSalt);

			if (strpos($encryptedPassword, '$2a$') === 0) {
				$encryptedPassword = '$2y$' . substr($encryptedPassword, strlen('$2a$'));
				return $encryptedPassword;
			}
		}

		return false;
	}

	public function encryptA($password, $salt)
	{
		if ($this->checkAEncryptionLevel() == 'a') {
			$methodAndSalt = '$2a$' . $salt;
			$encryptedPassword = crypt($password, $methodAndSalt);

			if (strpos($encryptedPassword, '$2a$') === 0) {
				return $encryptedPassword;
			}
		}

		return false;
	}

	/**
	 * The algorithm returned by using '$2a$' is not consistent -
	 * it might be either the correct (y), incorrect (x) or mostly-correct (a)
	 * version, depending on the version of PHP and the operating system,
	 * so we need to test it.
	 */
	public function checkAEncryptionLevel()
	{
		// Test hashes taken from
		// http://cvsweb.openwall.com/cgi/cvsweb.cgi/~checkout~/Owl/packages/glibc
		//    /crypt_blowfish/wrapper.c?rev=1.9.2.1;content-type=text%2Fplain
		$xOrY = crypt("\xff\xa334\xff\xff\xff\xa3345", '$2a$05$/OK.fbVrR/bpIqNJ5ianF.o./n25XVfn6oAPaUvHe.Csk4zRfsYPi')
			== '$2a$05$/OK.fbVrR/bpIqNJ5ianF.o./n25XVfn6oAPaUvHe.Csk4zRfsYPi';
		$yOrA = crypt("\xa3", '$2a$05$/OK.fbVrR/bpIqNJ5ianF.Sa7shbm4.OzKpvFnX1pQLmQW96oUlCq')
			== '$2a$05$/OK.fbVrR/bpIqNJ5ianF.Sa7shbm4.OzKpvFnX1pQLmQW96oUlCq';

		if ($xOrY && $yOrA) {
			return 'y';
		} elseif ($xOrY) {
			return 'x';
		} elseif ($yOrA) {
			return 'a';
		}

		return 'unknown';
	}

	/**
	 * self::$cost param is forced to be two digits with leading zeroes for ints 4-9
	 *
	 * @param string $password
	 * @param Member $member
	 * @return string
	 */
	public function salt($password, $member = null)
	{
		$generator = new RandomGenerator();
		return sprintf('%02d', self::$cost) . '$' . substr($generator->randomToken('sha1'), 0, 22);
	}

	public function check($hash, $password, $salt = null, $member = null)
	{
		if (strpos($hash, '$2y$') === 0) {
			return $hash === $this->encryptY($password, $salt);
		} elseif (strpos($hash, '$2a$') === 0) {
			return $hash === $this->encryptA($password, $salt);
		} elseif (strpos($hash, '$2x$') === 0) {
			return $hash === $this->encryptX($password, $salt);
		}

		return false;
	}
}