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<?php |
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|
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/** |
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* This class provides the functionality to encrypt |
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* and decrypt access tokens stored by the application |
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* @author Ben Tadiar <ben@handcraftedbyben.co.uk> |
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* @link https://github.com/benthedesigner/dropbox |
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* @package Dropbox\Oauth |
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* @subpackage Storage |
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*/ |
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|
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class Dropbox_Encrypter |
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{ |
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// Encryption settings - default settings yield encryption to AES (256-bit) standard |
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// @todo Provide PHPDOC for each class constant |
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const CIPHER = MCRYPT_RIJNDAEL_128; |
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const MODE = MCRYPT_MODE_CBC; |
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const KEY_SIZE = 32; |
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const IV_SIZE = 16; |
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|
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/** |
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* Encryption key |
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* @var null|string |
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*/ |
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private $key = null; |
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|
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/** |
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* Check Mcrypt is loaded and set the encryption key |
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* @param string $key |
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* @return void |
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*/ |
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public function __construct($key) |
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{ |
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if (!extension_loaded('mcrypt')) { |
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throw new Dropbox_Exception('The storage encrypter requires the PHP MCrypt extension to be available. Please check your PHP configuration.'); |
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} elseif (preg_match('/^[A-Za-z0-9]+$/', $key) && $length = strlen($key) === self::KEY_SIZE) { |
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# Short-cut so that the mbstring extension is not required |
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$this->key = $key; |
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} elseif (($length = mb_strlen($key, '8bit')) !== self::KEY_SIZE) { |
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throw new Dropbox_Exception('Expecting a ' . self::KEY_SIZE . ' byte key, got ' . $length); |
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} else { |
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// Set the encryption key |
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$this->key = $key; |
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} |
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} |
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|
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/** |
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* Encrypt the OAuth token |
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* @param \stdClass $token Serialized token object |
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* @return string |
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*/ |
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public function encrypt($token) |
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{ |
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// This now sends all Windows users to MCRYPT_RAND - used to send PHP>5.3 to MCRYPT_DEV_URANDOM, but we came across a user this failed for |
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// Only MCRYPT_RAND is available on Windows prior to PHP 5.3 |
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if (version_compare(phpversion(), '5.3.0', '<') && strtoupper(substr(php_uname('s'), 0, 3)) === 'WIN') { |
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$crypt_source = MCRYPT_RAND; |
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} elseif (@is_readable("/dev/urandom")) { |
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// Note that is_readable is not a true test of whether the mcrypt_create_iv call would work, because when open_basedir restrictions exist, is_readable returns false, but mcrypt_create_iv is not subject to that restriction internally, so would actually have succeeded. |
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$crypt_source = MCRYPT_DEV_URANDOM; |
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} else { |
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$crypt_source = MCRYPT_RAND; |
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} |
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$iv = @mcrypt_create_iv(self::IV_SIZE, $crypt_source); |
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|
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if ($iv === false && $crypt_source != MCRYPT_RAND) { |
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$iv = mcrypt_create_iv(self::IV_SIZE, MCRYPT_RAND); |
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} |
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|
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$cipherText = @mcrypt_encrypt(self::CIPHER, $this->key, $token, self::MODE, $iv); |
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return base64_encode($iv . $cipherText); |
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} |
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|
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/** |
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* Decrypt the ciphertext |
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* @param string $cipherText |
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* @return object \stdClass Unserialized token |
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*/ |
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public function decrypt($cipherText) |
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{ |
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$cipherText = base64_decode($cipherText); |
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$iv = substr($cipherText, 0, self::IV_SIZE); |
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$cipherText = substr($cipherText, self::IV_SIZE); |
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$token = @mcrypt_decrypt(self::CIPHER, $this->key, $cipherText, self::MODE, $iv); |
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return $token; |
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} |
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} |
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|
