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<?php |
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/** |
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* Nextcloud - passman |
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* |
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* @copyright Copyright (c) 2016, Sander Brand ([email protected]) |
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* @copyright Copyright (c) 2016, Marcos Zuriaga Miguel ([email protected]) |
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* @license GNU AGPL version 3 or any later version |
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU Affero General Public License as |
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* published by the Free Software Foundation, either version 3 of the |
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* License, or (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Affero General Public License for more details. |
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* |
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* You should have received a copy of the GNU Affero General Public License |
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* along with this program. If not, see <http://www.gnu.org/licenses/>. |
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* |
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*/ |
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namespace OCA\Passman\Service; |
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// Class copied from http://stackoverflow.com/questions/5089841/two-way-encryption-i-need-to-store-passwords-that-can-be-retrieved?answertab=votes#tab-top |
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// Upgraded to use openssl |
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use Icewind\SMB\Exception\Exception; |
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use OCA\Passman\Db\Credential; |
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use OCA\Passman\Db\File; |
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/** |
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* A class to handle secure encryption and decryption of arbitrary data |
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* |
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* Note that this is not just straight encryption. It also has a few other |
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* features in it to make the encrypted data far more secure. Note that any |
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* other implementations used to decrypt data will have to do the same exact |
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* operations. |
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* |
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* Security Benefits: |
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* |
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* - Uses Key stretching |
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* - Hides the Initialization Vector |
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* - Does HMAC verification of source data |
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* |
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*/ |
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class EncryptService { |
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/** |
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* Supported cipher algorithms accompanied by their key/block sizes in bytes |
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* |
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* OpenSSL has no equivalent of mcrypt_get_key_size() and mcrypt_get_block_size() hence sizes stored here. |
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* |
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* @var array |
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*/ |
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const SUPPORTED_ALGORITHMS = array( |
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'aes-256-cbc' => array('name' => 'AES-256', 'keySize' => 32, 'blockSize' => 32), |
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'bf' => array('name' => 'BF', 'keySize' => 16, 'blockSize' => 8), |
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'des' => array('name' => 'DES', 'keySize' => 7, 'blockSize' => 8), |
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'des-ede3' => array('name' => 'DES-EDE3', 'keySize' => 21, 'blockSize' => 8), // 3 different 56-bit keys |
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'cast5' => array('name' => 'CAST5', 'keySize' => 16, 'blockSize' => 8), |
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); |
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const OP_ENCRYPT = 'encrypt'; |
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const OP_DECRYPT = 'decrypt'; |
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// The fields of a credential which are encrypted |
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public $encrypted_credential_fields = array( |
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'description', 'username', 'password', 'files', 'custom_fields', 'otp', 'email', 'tags', 'url' |
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); |
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// Contains the server key |
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private $server_key; |
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/** |
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* @var string $cipher The openssl cipher to use for this instance |
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*/ |
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protected $cipher = ''; |
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/** |
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* @var int $rounds The number of rounds to feed into PBKDF2 for key generation |
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*/ |
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protected $rounds = 100; |
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/** |
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* Constructor! |
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* |
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* @param SettingsService $settings |
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*/ |
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public function __construct(SettingsService $settings) { |
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$this->cipher = $settings->getAppSetting('server_side_encryption', 'aes-256-cbc'); |
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$password_salt = \OC::$server->getConfig()->getSystemValue('passwordsalt', ''); |
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$secret = \OC::$server->getConfig()->getSystemValue('secret', ''); |
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$this->server_key = $password_salt . $secret; |
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$this->rounds = $settings->getAppSetting('rounds_pbkdf2_stretching', 100); |
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} |
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/** |
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* Create an encryption key. Based on given parameters |
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* |
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* @param string $userKey The user key to use. This should be specific to this user. |
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* @param string $serverKey The server key |
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* @param string $userSuppliedKey A key from the credential (eg guid, name or tags) |
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* @return string |
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*/ |
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public static function makeKey($userKey, $serverKey, $userSuppliedKey) { |
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$key = hash_hmac('sha512', $userKey, $serverKey); |
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$key = hash_hmac('sha512', $key, $userSuppliedKey); |
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return $key; |
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} |
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/** |
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* Get the maximum key size for the selected cipher and mode of operation |
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* |
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* @return int Value is in bytes |
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*/ |
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public function getKeySize() { |
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return EncryptService::SUPPORTED_ALGORITHMS[$this->cipher]['keySize']; |
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} |
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/** |
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* Decrypt the data with the provided key |
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* |
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* @param string $data_hex The encrypted datat to decrypt |
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* @param string $key The key to use for decryption |
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* |
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* @returns string|false The returned string if decryption is successful |
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* false if it is not |
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*/ |
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public function decrypt($data_hex, $key) { |
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if (!function_exists('hex2bin')) { |
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function hex2bin($str) { |
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$sbin = ""; |
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$len = strlen($str); |
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for ($i = 0; $i < $len; $i += 2) { |
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$sbin .= pack("H*", substr($str, $i, 2)); |
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} |
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return $sbin; |
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} |
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} |
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$data = hex2bin($data_hex); |
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$salt = substr($data, 0, 128); |
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$enc = substr($data, 128, -64); |
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$mac = substr($data, -64); |
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list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key); |
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if (!$this->hash_equals(hash_hmac('sha512', $enc, $macKey, true), $mac)) { |
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return false; |
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} |
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$dec = openssl_decrypt($enc, $this->cipher, $cipherKey, true, $iv); |
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$data = $this->unpad($dec); |
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return $data; |
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} |
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/** |
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* Encrypt the supplied data using the supplied key |
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* |
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* @param string $data The data to encrypt |
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* @param string $key The key to encrypt with |
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* |
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* @returns string The encrypted data |
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*/ |
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public function encrypt($data, $key) { |
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if (function_exists('random_bytes')) { |
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$salt = random_bytes(128); |
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} else { |
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$salt = openssl_random_pseudo_bytes(128); |
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} |
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list ($cipherKey, $macKey, $iv) = $this->getKeys($salt, $key); |
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$data = $this->pad($data); |
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$enc = openssl_encrypt($data, $this->cipher, $cipherKey, true, $iv); |
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$mac = hash_hmac('sha512', $enc, $macKey, true); |
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$data = bin2hex($salt . $enc . $mac); |
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return $data; |
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} |
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/** |
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* Generates a set of keys given a random salt and a master key |
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* |
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* @param string $salt A random string to change the keys each encryption |
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* @param string $key The supplied key to encrypt with |
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* |
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* @returns array An array of keys (a cipher key, a mac key, and a IV) |
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*/ |
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protected function getKeys($salt, $key) { |
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$ivSize = openssl_cipher_iv_length($this->cipher); |
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$keySize = openssl_cipher_iv_length($this->cipher); |
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$length = 2 * $keySize + $ivSize; |
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$key = $this->pbkdf2('sha512', $key, $salt, $this->rounds, $length); |
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$cipherKey = substr($key, 0, $keySize); |
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$macKey = substr($key, $keySize, $keySize); |
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$iv = substr($key, 2 * $keySize); |
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return array($cipherKey, $macKey, $iv); |
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} |
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protected function hash_equals($a, $b) { |
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if (function_exists('random_bytes')) { |
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$key = random_bytes(128); |
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} else { |
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$key = openssl_random_pseudo_bytes(128); |
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} |
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return hash_hmac('sha512', $a, $key) === hash_hmac('sha512', $b, $key); |
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} |
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/** |
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* Stretch the key using the PBKDF2 algorithm |
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* |
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* @see http://en.wikipedia.org/wiki/PBKDF2 |
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* |
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* @param string $algo The algorithm to use |
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* @param string $key The key to stretch |
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* @param string $salt A random salt |
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* @param int $rounds The number of rounds to derive |
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* @param int $length The length of the output key |
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* |
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* @returns string The derived key. |
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*/ |
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protected function pbkdf2($algo, $key, $salt, $rounds, $length) { |
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$size = strlen(hash($algo, '', true)); |
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$len = ceil($length / $size); |
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$result = ''; |
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for ($i = 1; $i <= $len; $i++) { |
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$tmp = hash_hmac($algo, $salt . pack('N', $i), $key, true); |
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$res = $tmp; |
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for ($j = 1; $j < $rounds; $j++) { |
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$tmp = hash_hmac($algo, $tmp, $key, true); |
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$res ^= $tmp; |
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} |
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$result .= $res; |
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} |
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return substr($result, 0, $length); |
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} |
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/** |
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* Pad the data with a random char chosen by the pad amount. |
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* |
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* @param $data |
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* @return string |
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*/ |
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protected function pad($data) { |
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$length = $this->getKeySize(); |
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$padAmount = $length - strlen($data) % $length; |
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if ($padAmount === 0) { |
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$padAmount = $length; |
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} |
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return $data . str_repeat(chr($padAmount), $padAmount); |
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} |
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/** |
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* Unpad the the data |
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* |
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* @param $data |
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* @return bool|string |
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*/ |
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protected function unpad($data) { |
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$length = $this->getKeySize(); |
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$last = ord($data[strlen($data) - 1]); |
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if ($last > $length) return false; |
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if (substr($data, -1 * $last) !== str_repeat(chr($last), $last)) { |
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return false; |
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} |
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return substr($data, 0, -1 * $last); |
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} |
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/** |
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* Encrypt a credential |
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* |
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* @param Credential|array $credential the credential to decrypt |
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* @return Credential|array |
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*/ |
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public function decryptCredential($credential) { |
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return $this->handleCredential($credential, EncryptService::OP_DECRYPT); |
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} |
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/** |
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* Encrypt a credential |
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* |
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* @param Credential|array $credential the credential to encrypt |
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* @return Credential|array |
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* @throws \Exception |
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*/ |
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public function encryptCredential($credential) { |
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return $this->handleCredential($credential, EncryptService::OP_ENCRYPT); |
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} |
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private function extractKeysFromCredential($credential) { |
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$userKey = ''; |
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$userSuppliedKey = ''; |
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if ($credential instanceof Credential) { |
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$userSuppliedKey = $credential->getLabel(); |
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$sk = $credential->getSharedKey(); |
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$userKey = (isset($sk)) ? $sk : $credential->getUserId(); |
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} |
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if (is_array($credential)) { |
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$userSuppliedKey = $credential['label']; |
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$userKey = (isset($credential['shared_key'])) ? $credential['shared_key'] : $credential['user_id']; |
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} |
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return array($userKey, $userSuppliedKey); |
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} |
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/** |
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* Handles the encryption / decryption of a credential |
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* |
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* @param Credential|array $credential the credential to encrypt |
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* @return Credential|array |
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* @throws \Exception |
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*/ |
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private function handleCredential($credential, $service_function) { |
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list($userKey, $userSuppliedKey) = $this->extractKeysFromCredential($credential); |
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$key = $this->makeKey($userKey, $this->server_key, $userSuppliedKey); |
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foreach ($this->encrypted_credential_fields as $field) { |
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if ($credential instanceof Credential) { |
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$field = str_replace(' ', '', str_replace('_', ' ', ucwords($field, '_'))); |
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$set = 'set' . $field; |
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$get = 'get' . $field; |
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$credential->{$set}($this->{$service_function}($credential->{$get}(), $key)); |
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} |
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if (is_array($credential)) { |
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$credential[$field] = $this->{$service_function}($credential[$field], $key); |
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} |
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} |
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return $credential; |
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} |
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/** |
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* Encrypt a file |
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* |
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* @param File|array $file |
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* @return File|array |
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*/ |
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public function encryptFile($file) { |
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return $this->handleFile($file, EncryptService::OP_ENCRYPT); |
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} |
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/** |
354
|
|
|
* Decrypt a file |
355
|
|
|
* |
356
|
|
|
* @param File|array $file |
357
|
|
|
* @return File|array |
358
|
|
|
*/ |
359
|
|
|
|
360
|
|
|
public function decryptFile($file) { |
361
|
|
|
return $this->handleFile($file, EncryptService::OP_DECRYPT); |
362
|
|
|
} |
363
|
|
|
|
364
|
|
|
/** |
365
|
|
|
* Handles the encryption / decryption of a File |
366
|
|
|
* |
367
|
|
|
* @param File|array $file the credential to encrypt |
368
|
|
|
* @return File|array |
369
|
|
|
* @throws \Exception |
370
|
|
|
*/ |
371
|
|
|
private function handleFile($file, $service_function) { |
372
|
|
|
$userKey = ''; |
373
|
|
|
$userSuppliedKey = ''; |
374
|
|
|
if ($file instanceof File) { |
375
|
|
|
$userSuppliedKey = $file->getFilename(); |
376
|
|
|
$userKey = md5($file->getMimetype()); |
377
|
|
|
} |
378
|
|
|
|
379
|
|
|
if (is_array($file)) { |
380
|
|
|
$userSuppliedKey = $file['size']; |
381
|
|
|
$userKey = md5($file['mimetype']); |
382
|
|
|
} |
383
|
|
|
|
384
|
|
|
$key = $this->makeKey($userKey, $this->server_key, $userSuppliedKey); |
385
|
|
|
|
386
|
|
|
|
387
|
|
|
if ($file instanceof File) { |
388
|
|
|
$file->setFilename($this->{$service_function}($file->getFilename(), $key)); |
389
|
|
|
$file->setFileData($this->{$service_function}($file->getFileData(), $key)); |
390
|
|
|
} |
391
|
|
|
|
392
|
|
|
if (is_array($file)) { |
393
|
|
|
$file['filename'] = $this->{$service_function}($file['filename'], $key); |
394
|
|
|
$file['file_data'] = $this->{$service_function}($file['file_data'], $key); |
395
|
|
|
} |
396
|
|
|
|
397
|
|
|
return $file; |
398
|
|
|
} |
399
|
|
|
} |