337 lines
8.7 KiB
PHP
337 lines
8.7 KiB
PHP
<?php
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/**
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* @author Björn Schießle <schiessle@owncloud.com>
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* @author Clark Tomlinson <fallen013@gmail.com>
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* @author Thomas Müller <thomas.mueller@tmit.eu>
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* @author Lukas Reschke <lukas@owncloud.com>
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*
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* @copyright Copyright (c) 2015, ownCloud, Inc.
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* @license AGPL-3.0
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*
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* This code 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, version 3,
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* as published by the Free Software Foundation.
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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, version 3,
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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\Encryption\Crypto;
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use OCA\Encryption\Util;
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use OCP\Encryption\IEncryptionModule;
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use OCA\Encryption\KeyManager;
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class Encryption implements IEncryptionModule {
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const ID = 'OC_DEFAULT_MODULE';
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const DISPLAY_NAME = 'ownCloud Default Encryption';
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/**
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* @var Crypt
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*/
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private $crypt;
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/** @var string */
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private $cipher;
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/** @var string */
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private $path;
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/** @var string */
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private $user;
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/** @var string */
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private $fileKey;
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/** @var string */
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private $writeCache;
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/** @var KeyManager */
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private $keyManager;
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/** @var array */
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private $accessList;
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/** @var boolean */
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private $isWriteOperation;
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/** @var Util */
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private $util;
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/**
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*
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* @param \OCA\Encryption\Crypto\Crypt $crypt
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* @param KeyManager $keyManager
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* @param Util $util
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*/
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public function __construct(Crypt $crypt, KeyManager $keyManager, Util $util) {
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$this->crypt = $crypt;
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$this->keyManager = $keyManager;
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$this->util = $util;
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}
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/**
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* @return string defining the technical unique id
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*/
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public function getId() {
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return self::ID;
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}
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/**
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* In comparison to getKey() this function returns a human readable (maybe translated) name
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*
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* @return string
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*/
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public function getDisplayName() {
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return self::DISPLAY_NAME;
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}
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/**
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* start receiving chunks from a file. This is the place where you can
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* perform some initial step before starting encrypting/decrypting the
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* chunks
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*
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* @param string $path to the file
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* @param string $user who read/write the file
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* @param array $header contains the header data read from the file
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* @param array $accessList who has access to the file contains the key 'users' and 'public'
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*
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* @return array $header contain data as key-value pairs which should be
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* written to the header, in case of a write operation
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* or if no additional data is needed return a empty array
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*/
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public function begin($path, $user, array $header, array $accessList) {
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if (isset($header['cipher'])) {
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$this->cipher = $header['cipher'];
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} else {
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$this->cipher = $this->crypt->getCipher();
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}
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$this->path = $this->getPathToRealFile($path);
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$this->accessList = $accessList;
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$this->user = $user;
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$this->writeCache = '';
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$this->isWriteOperation = false;
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$this->fileKey = $this->keyManager->getFileKey($this->path, $this->user);
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return array('cipher' => $this->cipher);
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}
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/**
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* last chunk received. This is the place where you can perform some final
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* operation and return some remaining data if something is left in your
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* buffer.
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*
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* @param string $path to the file
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* @return string remained data which should be written to the file in case
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* of a write operation
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*/
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public function end($path) {
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$result = '';
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if ($this->isWriteOperation) {
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if (!empty($this->writeCache)) {
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$result = $this->crypt->symmetricEncryptFileContent($this->writeCache, $this->fileKey);
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$this->writeCache = '';
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}
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$publicKeys = array();
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foreach ($this->accessList['users'] as $uid) {
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$publicKeys[$uid] = $this->keyManager->getPublicKey($uid);
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}
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$publicKeys = $this->keyManager->addSystemKeys($this->accessList, $publicKeys);
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$encryptedKeyfiles = $this->crypt->multiKeyEncrypt($this->fileKey, $publicKeys);
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$this->keyManager->setAllFileKeys($this->path, $encryptedKeyfiles);
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}
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return $result;
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}
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/**
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* encrypt data
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*
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* @param string $data you want to encrypt
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* @return mixed encrypted data
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*/
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public function encrypt($data) {
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$this->isWriteOperation = true;
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if (empty($this->fileKey)) {
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$this->fileKey = $this->crypt->generateFileKey();
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}
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// If extra data is left over from the last round, make sure it
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// is integrated into the next 6126 / 8192 block
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if ($this->writeCache) {
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// Concat writeCache to start of $data
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$data = $this->writeCache . $data;
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// Clear the write cache, ready for reuse - it has been
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// flushed and its old contents processed
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$this->writeCache = '';
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}
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$encrypted = '';
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// While there still remains some data to be processed & written
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while (strlen($data) > 0) {
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// Remaining length for this iteration, not of the
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// entire file (may be greater than 8192 bytes)
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$remainingLength = strlen($data);
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// If data remaining to be written is less than the
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// size of 1 6126 byte block
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if ($remainingLength < 6126) {
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// Set writeCache to contents of $data
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// The writeCache will be carried over to the
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// next write round, and added to the start of
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// $data to ensure that written blocks are
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// always the correct length. If there is still
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// data in writeCache after the writing round
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// has finished, then the data will be written
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// to disk by $this->flush().
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$this->writeCache = $data;
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// Clear $data ready for next round
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$data = '';
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} else {
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// Read the chunk from the start of $data
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$chunk = substr($data, 0, 6126);
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$encrypted .= $this->crypt->symmetricEncryptFileContent($chunk, $this->fileKey);
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// Remove the chunk we just processed from
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// $data, leaving only unprocessed data in $data
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// var, for handling on the next round
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$data = substr($data, 6126);
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}
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}
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return $encrypted;
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}
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/**
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* decrypt data
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*
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* @param string $data you want to decrypt
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* @return mixed decrypted data
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*/
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public function decrypt($data) {
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$result = '';
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if (!empty($data)) {
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$result = $this->crypt->symmetricDecryptFileContent($data, $this->fileKey);
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}
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return $result;
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}
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/**
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* update encrypted file, e.g. give additional users access to the file
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*
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* @param string $path path to the file which should be updated
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* @param string $uid of the user who performs the operation
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* @param array $accessList who has access to the file contains the key 'users' and 'public'
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* @return boolean
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*/
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public function update($path, $uid, array $accessList) {
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$fileKey = $this->keyManager->getFileKey($path, $uid);
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$publicKeys = array();
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foreach ($accessList['users'] as $user) {
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$publicKeys[$user] = $this->keyManager->getPublicKey($user);
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}
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$publicKeys = $this->keyManager->addSystemKeys($accessList, $publicKeys);
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$encryptedFileKey = $this->crypt->multiKeyEncrypt($fileKey, $publicKeys);
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$this->keyManager->deleteAllFileKeys($path);
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$this->keyManager->setAllFileKeys($path, $encryptedFileKey);
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return true;
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}
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/**
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* add system keys such as the public share key and the recovery key
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*
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* @param array $accessList
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* @param array $publicKeys
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* @return array
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*/
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public function addSystemKeys(array $accessList, array $publicKeys) {
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if (!empty($accessList['public'])) {
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$publicKeys[$this->keyManager->getPublicShareKeyId()] = $this->keyManager->getPublicShareKey();
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}
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if ($this->keyManager->recoveryKeyExists() &&
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$this->util->isRecoveryEnabledForUser()) {
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$publicKeys[$this->keyManager->getRecoveryKeyId()] = $this->keyManager->getRecoveryKey();
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}
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return $publicKeys;
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}
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/**
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* should the file be encrypted or not
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*
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* @param string $path
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* @return boolean
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*/
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public function shouldEncrypt($path) {
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$parts = explode('/', $path);
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if (count($parts) < 3) {
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return false;
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}
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if ($parts[2] == 'files') {
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return true;
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}
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if ($parts[2] == 'files_versions') {
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return true;
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}
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return false;
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}
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/**
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* get size of the unencrypted payload per block.
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* ownCloud read/write files with a block size of 8192 byte
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*
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* @return integer
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*/
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public function getUnencryptedBlockSize() {
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return 6126;
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}
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/**
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* @param string $path
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* @return string
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*/
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protected function getPathToRealFile($path) {
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$realPath = $path;
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$parts = explode('/', $path);
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if ($parts[2] === 'files_versions') {
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$realPath = '/' . $parts[1] . '/files/' . implode('/', array_slice($parts, 3));
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$length = strrpos($realPath, '.');
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$realPath = substr($realPath, 0, $length);
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}
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return $realPath;
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}
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}
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