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lib/private/Files/Storage/Wrapper/Encryption.php

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<?php
/**
 * @author Björn Schießle <bjoern@schiessle.org>
 * @author Joas Schilling <coding@schilljs.com>
 * @author Lukas Reschke <lukas@statuscode.ch>
 * @author Robin Appelman <icewind@owncloud.com>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Vincent Petry <pvince81@owncloud.com>
 *
 * @copyright Copyright (c) 2018, ownCloud GmbH
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OC\Files\Storage\Wrapper;

use OC\Encryption\Exceptions\ModuleDoesNotExistsException;
use OC\Encryption\Update;
use OC\Encryption\Util;
use OC\Files\Cache\CacheEntry;
use OC\Files\Filesystem;
use OC\Files\Mount\Manager;
use OC\Files\Storage\LocalTempFileTrait;
use OC\Memcache\ArrayCache;
use OCP\Encryption\Exceptions\GenericEncryptionException;
use OCP\Encryption\IFile;
use OCP\Encryption\IManager;
use OCP\Encryption\Keys\IStorage;
use OCP\Files\Mount\IMountPoint;
use OCP\Files\Storage;
use OCP\ILogger;
use OCP\Files\Cache\ICacheEntry;
use OC_Util;

class Encryption extends Wrapper {
    use LocalTempFileTrait;

    /** @var string */
    private $mountPoint;

    /** @var \OC\Encryption\Util */
    private $util;

    /** @var \OCP\Encryption\IManager */
    private $encryptionManager;

    /** @var \OCP\ILogger */
    private $logger;

    /** @var string */
    private $uid;

    /** @var array */
    protected $unencryptedSize;

    /** @var \OCP\Encryption\IFile */
    private $fileHelper;

    /** @var IMountPoint */
    private $mount;

    /** @var IStorage */
    private $keyStorage;

    /** @var Update */
    private $update;

    /** @var Manager */
    private $mountManager;

    /** @var array remember for which path we execute the repair step to avoid recursions */
    private $fixUnencryptedSizeOf = [];

    /** @var  ArrayCache */
    private $arrayCache;

    /** @var array which has information of sourcePath during rename operation */
    private $sourcePath;

    private static $disableWriteEncryption = false;

    /**
     * @param array $parameters
     * @param IManager $encryptionManager
     * @param Util $util
     * @param ILogger $logger
     * @param IFile $fileHelper
     * @param string $uid
     * @param IStorage $keyStorage
     * @param Update $update
     * @param Manager $mountManager
     * @param ArrayCache $arrayCache
     */
    public function __construct(
        $parameters,
        IManager $encryptionManager = null,
        Util $util = null,
        ILogger $logger = null,
        IFile $fileHelper = null,
        $uid = null,
        IStorage $keyStorage = null,
        Update $update = null,
        Manager $mountManager = null,
        ArrayCache $arrayCache = null
    ) {
        $this->mountPoint = $parameters['mountPoint'];
        $this->mount = $parameters['mount'];
        $this->encryptionManager = $encryptionManager;
        $this->util = $util;
        $this->logger = $logger;
        $this->uid = $uid;
        $this->fileHelper = $fileHelper;
        $this->keyStorage = $keyStorage;
        $this->unencryptedSize = [];
        $this->update = $update;
        $this->mountManager = $mountManager;
        $this->arrayCache = $arrayCache;
        parent::__construct($parameters);
    }

    /**
     * see http://php.net/manual/en/function.filesize.php
     * The result for filesize when called on a folder is required to be 0
     *
     * @param string $path
     * @return int
     */
    public function filesize($path) {
        $fullPath = $this->getFullPath($path);

        /** @var CacheEntry $info */
        $info = $this->getCache()->get($path);
        if (isset($this->unencryptedSize[$fullPath])) {
            $size = $this->unencryptedSize[$fullPath];
            // update file cache
            if ($info instanceof ICacheEntry) {
                '@phan-var \OC\Files\Cache\CacheEntry $info';
                $info = $info->getData();
                $info['encrypted'] = $info['encryptedVersion'];
            } else {
                if (!\is_array($info)) {
                    $info = [];
                }
                $info['encrypted'] = true;
            }

            $info['size'] = $size;
            $this->getCache()->put($path, $info);

            return $size;
        }

        if (isset($info['fileid']) && $info['encrypted']) {
            return $this->verifyUnencryptedSize($path, $info['size']);
        }

        return $this->storage->filesize($path);
    }

    /**
     * @param string $path
     * @return array
     */
    public function getMetaData($path) {
        $data = $this->storage->getMetaData($path);
        if ($data === null) {
            return null;
        }
        $fullPath = $this->getFullPath($path);
        $info = $this->getCache()->get($path);

        if (isset($this->unencryptedSize[$fullPath])) {
            $data['encrypted'] = true;
            $data['size'] = $this->unencryptedSize[$fullPath];
        } else {
            if (isset($info['fileid']) && $info['encrypted']) {
                $data['size'] = $this->verifyUnencryptedSize($path, $info['size']);
                $data['encrypted'] = true;
            }
        }

        if (isset($info['encryptedVersion']) && $info['encryptedVersion'] > 1) {
            $data['encryptedVersion'] = $info['encryptedVersion'];
        }

        return $data;
    }

    /**
     * see http://php.net/manual/en/function.file_get_contents.php
     *
     * @param string $path
     * @return string
     */
    public function file_get_contents($path) {
        if ($this->encryptionManager->isEnabled() !== false) {
            $encryptionModule = $this->getEncryptionModule($path);

            if ($encryptionModule) {
                $handle = $this->fopen($path, "r");
                if (!$handle) {
                    return false;
                }
                $data = \stream_get_contents($handle);
                \fclose($handle);
                return $data;
            }
        }
        return $this->storage->file_get_contents($path);
    }

    /**
     * see http://php.net/manual/en/function.file_put_contents.php
     *
     * @param string $path
     * @param string $data
     * @return bool
     */
    public function file_put_contents($path, $data) {
        // file put content will always be translated to a stream write
        $handle = $this->fopen($path, 'w');
        if (\is_resource($handle)) {
            $written = \fwrite($handle, $data);
            \fclose($handle);
            return $written;
        }

        return false;
    }

    /**
     * see http://php.net/manual/en/function.unlink.php
     *
     * @param string $path
     * @return bool
     */
    public function unlink($path) {
        $fullPath = $this->getFullPath($path);
        if ($this->util->isExcluded($fullPath)) {
            return $this->storage->unlink($path);
        }

        $encryptionModule = ($this->encryptionManager->isEnabled()) ? $this->getEncryptionModule($path) : "";
        if ($encryptionModule) {
            $this->keyStorage->deleteAllFileKeys($this->getFullPath($path));
        }

        return $this->storage->unlink($path);
    }

    /**
     * see http://php.net/manual/en/function.rename.php
     *
     * @param string $path1
     * @param string $path2
     * @return bool
     */
    public function rename($path1, $path2) {
        $renameOk = false;
        $copyKeysOk = true;  // assume keys are copied, in case we deal with versions

        $isVersion = $this->isVersion($path2) || $this->isVersion($path1);
        // if encryption is disabled, consider it's a version in order to skip
        // moving the keys
        $isVersion = $isVersion || !$this->encryptionManager->isEnabled();

        $source = $this->getFullPath($path1);
        $target = $this->getFullPath($path2);
        $keysExcluded = $this->util->isExcluded($source);

        if (!$isVersion && !$keysExcluded) {
            // versions always use the keys from the original file, so we can skip
            // this step for versions
            // Keys can also be excluded if we're moving the keys themselves. It could
            // happen with the encryption:change-key-storage-root command
            if (isset($this->unencryptedSize[$source])) {
                $this->unencryptedSize[$target] = $this->unencryptedSize[$source];
            }

            $copyKeysOk = $this->keyStorage->copyKeys($source, $target);
            if ($copyKeysOk) {
                $module = $this->getEncryptionModule($path2);
                if ($module) {
                    $module->update($target, $this->uid, []);
                }
            }
        }

        if ($copyKeysOk) {
            $renameOk = $this->storage->rename($path1, $path2);
            if ($isVersion || $keysExcluded) {
                // no need to deal with the keys
                return $renameOk;
            }

            // need to remove the keys, either the old ones if the rename
            // succeeded, or the new ones if the rename failed
            if ($renameOk) {
                $sourceKeyDeleteOk = $this->keyStorage->deleteAllFileKeys($source);
                if (!$sourceKeyDeleteOk) {
                    $this->logger->error("Renaming {$path1} to {$path2} succeeded, but key for file {$target} wasn't removed from its original location");
                }
            } else {
                $this->logger->error("Renaming {$path1} to {$path2} failed");
                $targetKeyDeleteOk = $this->keyStorage->deleteAllFileKeys($target);
                if (!$targetKeyDeleteOk) {
                    $this->logger->error("Copied key for file {$source} wasn't removed from its target location");
                }
            }
        } else {
            $this->logger->error("Failed to copy keys while renaming {$path1} to {$path2}");
        }

        return $renameOk && $copyKeysOk;
    }

    /**
     * see http://php.net/manual/en/function.rmdir.php
     *
     * @param string $path
     * @return bool
     */
    public function rmdir($path) {
        $result = $this->storage->rmdir($path);
        $fullPath = $this->getFullPath($path);
        if ($result &&
            $this->util->isExcluded($fullPath) === false &&
            $this->encryptionManager->isEnabled()
        ) {
            $this->keyStorage->deleteAllFileKeys($fullPath);
        }

        return $result;
    }

    /**
     * check if a file can be read
     *
     * @param string $path
     * @return bool
     */
    public function isReadable($path) {
        $isReadable = true;

        $metaData = $this->getMetaData($path);
        if (
            !$this->is_dir($path) &&
            isset($metaData['encrypted']) &&
            $metaData['encrypted'] === true
        ) {
            $fullPath = $this->getFullPath($path);
            $module = $this->getEncryptionModule($path);
            $isReadable = $module->isReadable($fullPath, $this->uid);
        }

        return $this->storage->isReadable($path) && $isReadable;
    }

    /**
     * see http://php.net/manual/en/function.copy.php
     *
     * @param string $path1
     * @param string $path2
     * @return bool
     */
    public function copy($path1, $path2) {
        $source = $this->getFullPath($path1);

        if ($this->util->isExcluded($source)) {
            return $this->storage->copy($path1, $path2);
        }

        // need to stream copy file by file in case we copy between a encrypted
        // and a unencrypted storage

        if (!($this->isVersion($path2) || $this->isVersion($path1))) {
            // NOTE: this is legacy code-path, and it is not clear why this is needed for standard files,
            // however for versions we should not unlink, because versions should always use the
            // key from the original file. Just create a 1:1 copy and done
            // ref. https://github.com/owncloud/encryption/issues/383
            $this->unlink($path2);
        }
        $result = $this->copyFromStorage($this, $path1, $path2);

        return $result;
    }

    /**
     * see http://php.net/manual/en/function.fopen.php
     *
     * @param string $path
     * @param string $mode
     * @return resource|bool
     * @throws GenericEncryptionException
     * @throws ModuleDoesNotExistsException
     */
    public function fopen($path, $mode) {
        // check if the file is stored in the array cache, this means that we
        // copy a file over to the versions folder, in this case we don't want to
        // decrypt it
        if ($this->arrayCache->hasKey('encryption_copy_version_' . $path)) {
            $this->arrayCache->remove('encryption_copy_version_' . $path);
            return $this->storage->fopen($path, $mode);
        }

        $encryptionEnabled = $this->encryptionManager->isEnabled();
        $shouldEncrypt = false;
        $encryptionModule = null;
        $header = $this->getHeader($path);
        $signed = (isset($header['signed']) && $header['signed'] === 'true') ? true : false;
        $fullPath = $this->getFullPath($path);
        $encryptionModuleId = $this->util->getEncryptionModuleId($header);

        if ($this->util->isExcluded($fullPath) === false) {
            $size = $unencryptedSize = 0;
            $realFile = OC_Util::stripPartialFileExtension($path);
            $targetExists = $this->file_exists($realFile) || $this->file_exists($path);
            $targetIsEncrypted = false;
            if ($targetExists) {
                // in case the file exists we require the explicit module as
                // specified in the file header - otherwise we need to fail hard to
                // prevent data loss on client side
                if (!empty($encryptionModuleId)) {
                    $data = $this->storage->getCache()->get($path);
                    if (isset($data['encrypted']) && $data['encrypted'] === true) {
                        $targetIsEncrypted = true;
                        $encryptionModule = $this->encryptionManager->getEncryptionModule($encryptionModuleId);
                    }
                }

                if ($this->file_exists($path)) {
                    $size = $this->storage->filesize($path);
                    $unencryptedSize = $this->filesize($path);
                } else {
                    $size = $unencryptedSize = 0;
                }
            }

            try {
                if (
                    $mode === 'w'
                    || $mode === 'w+'
                    || $mode === 'wb'
                    || $mode === 'wb+'
                ) {
                    // don't overwrite encrypted files if encryption is not enabled
                    if ($targetIsEncrypted && $encryptionEnabled === false) {
                        throw new GenericEncryptionException('Tried to access encrypted file but encryption is not enabled');
                    }
                    if ($encryptionEnabled) {
                        // if $encryptionModuleId is empty, the default module will be used
                        $encryptionModule = $this->encryptionManager->getEncryptionModule($encryptionModuleId);
                        $shouldEncrypt = $encryptionModule->shouldEncrypt($fullPath);
                        $signed = true;
                    }
                } else {
                    $info = $this->getCache()->get($path);
                    // only get encryption module if we found one in the header
                    // or if file should be encrypted according to the file cache
                    if (!empty($encryptionModuleId)) {
                        $encryptionModule = $this->encryptionManager->getEncryptionModule($encryptionModuleId);
                        $shouldEncrypt = true;
                    } elseif (empty($encryptionModuleId) && $info['encrypted'] === true) {
                        // we come from a old installation. No header and/or no module defined
                        // but the file is encrypted. In this case we need to use the
                        // OC_DEFAULT_MODULE to read the file
                        $encryptionModule = $this->encryptionManager->getEncryptionModule('OC_DEFAULT_MODULE');
                        $shouldEncrypt = true;
                        $targetIsEncrypted = true;
                    }
                }
            } catch (ModuleDoesNotExistsException $e) {
                $this->logger->warning('Encryption module "' . $encryptionModuleId .
                    '" not found, file will be stored unencrypted (' . $e->getMessage() . ')');
            }

            // encryption disabled on write of new file and write to existing unencrypted file -> don't encrypt
            if (!$encryptionEnabled || !$this->mount->getOption('encrypt', true)) {
                if (!$targetExists || !$targetIsEncrypted) {
                    $shouldEncrypt = false;
                }
            }

            if ($shouldEncrypt === true && $encryptionModule !== null) {
                /**
                 * The check of $disableWriteEncryption, required to get the file in the decrypted state.
                 * It will help us get the normal file handler. And hence we can re-encrypt
                 * the file when necessary, later. The true/false of $getDecryptedFile decides whether
                 * to keep the file decrypted or not. The intention is to get the data decrypt
                 * for write mode.
                 */
                if (self::$disableWriteEncryption && ($mode !== 'r')) {
                    return $this->getWrapperStorage()->fopen($path, $mode);
                }

                $headerSize = $this->getHeaderSize($path);
                $source = $this->storage->fopen($path, $mode);
                if (!\is_resource($source)) {
                    return false;
                }

                if (isset($this->sourcePath[$path])) {
                    $sourceFileOfRename = $this->sourcePath[$path];
                } else {
                    $sourceFileOfRename = null;
                }
                $handle = \OC\Files\Stream\Encryption::wrap(
                    $source,
                    $path,
                    $fullPath,
                    $header,
                    $this->uid,
                    $encryptionModule,
                    $this->storage,
                    $this,
                    $this->util,
                    $this->fileHelper,
                    $mode,
                    $size,
                    $unencryptedSize,
                    $headerSize,
                    $signed,
                    $sourceFileOfRename
                );
                unset($this->sourcePath[$path]);

                return $handle;
            }
        }

        return $this->storage->fopen($path, $mode);
    }

    /**
     * perform some plausibility checks if the the unencrypted size is correct.
     * If not, we calculate the correct unencrypted size and return it
     *
     * @param string $path internal path relative to the storage root
     * @param int $unencryptedSize size of the unencrypted file
     *
     * @return int unencrypted size
     */
    protected function verifyUnencryptedSize($path, $unencryptedSize) {
        $size = $this->storage->filesize($path);
        $result = $unencryptedSize;

        if ($unencryptedSize < 0 ||
            ($size > 0 && $unencryptedSize === $size)
        ) {
            // check if we already calculate the unencrypted size for the
            // given path to avoid recursions
            if (isset($this->fixUnencryptedSizeOf[$this->getFullPath($path)]) === false) {
                $this->fixUnencryptedSizeOf[$this->getFullPath($path)] = true;
                try {
                    $result = $this->fixUnencryptedSize($path, $size, $unencryptedSize);
                } catch (\Exception $e) {
                    $this->logger->error('Couldn\'t re-calculate unencrypted size for '. $path);
                    $this->logger->logException($e);
                }
                unset($this->fixUnencryptedSizeOf[$this->getFullPath($path)]);
            }
        }

        return $result;
    }

    /**
     * calculate the unencrypted size
     *
     * @param string $path internal path relative to the storage root
     * @param int $size size of the physical file
     * @param int $unencryptedSize size of the unencrypted file
     *
     * @return int calculated unencrypted size
     */
    protected function fixUnencryptedSize($path, $size, $unencryptedSize) {
        $headerSize = $this->getHeaderSize($path);
        $header = $this->getHeader($path);
        $encryptionModule = $this->getEncryptionModule($path);

        $stream = $this->storage->fopen($path, 'r');

        // if we couldn't open the file we return the old unencrypted size
        if (!\is_resource($stream)) {
            $this->logger->error('Could not open ' . $path . '. Recalculation of unencrypted size aborted.');
            return $unencryptedSize;
        }

        $newUnencryptedSize = 0;
        $size -= $headerSize;
        $blockSize = $this->util->getBlockSize();

        // if a header exists we skip it
        if ($headerSize > 0) {
            \fread($stream, $headerSize);
        }

        // fast path, else the calculation for $lastChunkNr is bogus
        if ($size === 0) {
            return 0;
        }

        // initialize encryption module to get the correct unencrypted block-size
        $encryptionModule->begin($this->getFullPath($path), $this->uid, 'r', $header, [], null);
        $signed = (isset($header['signed']) && $header['signed'] === 'true') ? true : false;
        $unencryptedBlockSize = $encryptionModule->getUnencryptedBlockSize($signed);

        // calculate last chunk nr
        // next highest is end of chunks, one subtracted is last one
        // we have to read the last chunk, we can't just calculate it (because of padding etc)

        $lastChunkNr = \ceil($size/ $blockSize)-1;
        // calculate last chunk position
        $lastChunkPos = ($lastChunkNr * $blockSize);
        // try to fseek to the last chunk, if it fails we have to read the whole file
        if (@\fseek($stream, $lastChunkPos, SEEK_CUR) === 0) {
            $newUnencryptedSize += $lastChunkNr * $unencryptedBlockSize;
        }

        $lastChunkContentEncrypted='';
        $count = $blockSize;

        while ($count > 0) {
            $data=\fread($stream, $blockSize);
            $count=\strlen($data);
            $lastChunkContentEncrypted .= $data;
            if (\strlen($lastChunkContentEncrypted) > $blockSize) {
                $newUnencryptedSize += $unencryptedBlockSize;
                $lastChunkContentEncrypted=\substr($lastChunkContentEncrypted, $blockSize);
            }
        }

        \fclose($stream);

        // we have to decrypt the last chunk to get it actual size
        $decryptedLastChunk = $encryptionModule->decrypt($lastChunkContentEncrypted, $lastChunkNr . 'end');
        $decryptedLastChunk .= $encryptionModule->end($this->getFullPath($path), $lastChunkNr . 'end');

        // calc the real file size with the size of the last chunk
        $newUnencryptedSize += \strlen($decryptedLastChunk);

        $this->updateUnencryptedSize($this->getFullPath($path), $newUnencryptedSize);

        // write to cache if applicable
        $cache = $this->storage->getCache();
        if ($cache) {
            $entry = $cache->get($path);
            $cache->update($entry['fileid'], ['size' => $newUnencryptedSize]);
        }

        return $newUnencryptedSize;
    }

    /**
     * @param Storage $sourceStorage
     * @param string $sourceInternalPath
     * @param string $targetInternalPath
     * @param bool $preserveMtime
     * @return bool
     */
    public function moveFromStorage(Storage $sourceStorage, $sourceInternalPath, $targetInternalPath, $preserveMtime = true) {
        if ($sourceStorage === $this) {
            return $this->rename($sourceInternalPath, $targetInternalPath);
        }

        // TODO clean this up once the underlying moveFromStorage in OC\Files\Storage\Wrapper\Common is fixed:
        // - call $this->storage->moveFromStorage() instead of $this->copyBetweenStorage
        // - copy the file cache update from  $this->copyBetweenStorage to this method
        // - copy the copyKeys() call from  $this->copyBetweenStorage to this method
        // - remove $this->copyBetweenStorage

        if (!$sourceStorage->isDeletable($sourceInternalPath)) {
            return false;
        }

        if (!$this->encryptionManager->isEnabled()) {
            return $this->storage->moveFromStorage($sourceStorage, $sourceInternalPath, $targetInternalPath, $preserveMtime);
        }
        $result = $this->copyBetweenStorage($sourceStorage, $sourceInternalPath, $targetInternalPath, $preserveMtime, true);
        if ($result) {
            if ($sourceStorage->is_dir($sourceInternalPath)) {
                $result &= $sourceStorage->rmdir($sourceInternalPath);
            } else {
                $result &= $sourceStorage->unlink($sourceInternalPath);
            }
        }
        return $result;
    }

    /**
     * Set the flag to true, so that the file would be
     * in the decrypted state.
     *
     * @param $isDisabled bool
     */
    public static function setDisableWriteEncryption($isDisabled) {
        self::$disableWriteEncryption = $isDisabled;
    }

    /**
     * @param Storage $sourceStorage
     * @param string $sourceInternalPath
     * @param string $targetInternalPath
     * @param bool $preserveMtime
     * @param bool $isRename
     * @return bool
     */
    public function copyFromStorage(Storage $sourceStorage, $sourceInternalPath, $targetInternalPath, $preserveMtime = false, $isRename = false) {
        // TODO clean this up once the underlying moveFromStorage in OC\Files\Storage\Wrapper\Common is fixed:
        // - call $this->storage->copyFromStorage() instead of $this->copyBetweenStorage
        // - copy the file cache update from  $this->copyBetweenStorage to this method
        // - copy the copyKeys() call from  $this->copyBetweenStorage to this method
        // - remove $this->copyBetweenStorage

        return $this->copyBetweenStorage($sourceStorage, $sourceInternalPath, $targetInternalPath, $preserveMtime, $isRename);
    }

    /**
     * Update the encrypted cache version in the database
     *
     * @param Storage $sourceStorage
     * @param string $sourceInternalPath
     * @param string $targetInternalPath
     * @param bool $isRename
     */
    private function updateEncryptedVersion(Storage $sourceStorage, $sourceInternalPath, $targetInternalPath, $isRename) {
        $isEncrypted = $this->encryptionManager->isEnabled() && $this->mount->getOption('encrypt', true) ? 1 : 0;
        $cacheInformation = [
            'encrypted' => (bool)$isEncrypted,
        ];
        if ($isEncrypted === 1) {
            $encryptedVersion = null;  // initialize as null for backwards compatibility
            $sourceInfo = $sourceStorage->getCache()->get($sourceInternalPath);
            if ($sourceInfo !== false) {
                $encryptedVersion = $sourceInfo['encryptedVersion'];
            }

            // In case of a move operation from an unencrypted to an encrypted
            // storage the old encrypted version would stay with "0" while the
            // correct value would be "1". Thus we manually set the value to "1"
            // for those cases.
            // See also https://github.com/owncloud/core/issues/23078
            if ($encryptedVersion === 0) {
                $encryptedVersion = 1;
            }

            $cacheInformation['encryptedVersion'] = $encryptedVersion;
        } else {
            $cacheInformation['encryptedVersion'] = 0;
        }

        // in case of a rename we need to manipulate the source cache because
        // this information will be kept for the new target
        if ($isRename && !($this->isVersion($sourceInternalPath) || $this->isVersion($targetInternalPath))) {
            /*
             * Rename is a process of creating a new file. Here we try to use the
             * incremented version of source file, for the destination file.
             * Note that if we're renaming or moving a version, the version is copied
             * without any change, so the encrypted version mustn't change in order to avoid
             * problems with the signature
             */
            $encryptedVersion = $sourceStorage->getCache()->get($sourceInternalPath)['encryptedVersion'];
            if ($this->encryptionManager->isEnabled() && $isEncrypted) {
                $cacheInformation['encryptedVersion'] = $encryptedVersion + 1;
            }
            $sourceStorage->getCache()->put($sourceInternalPath, $cacheInformation);
        } else {
            $this->getCache()->put($targetInternalPath, $cacheInformation);
        }
    }

    /**
     * copy file between two storages
     *
     * @param Storage $sourceStorage
     * @param string $sourceInternalPath
     * @param string $targetInternalPath
     * @param bool $preserveMtime
     * @param bool $isRename
     * @return bool
     * @throws \Exception
     */
    private function copyBetweenStorage(Storage $sourceStorage, $sourceInternalPath, $targetInternalPath, $preserveMtime, $isRename) {
        // for versions we have nothing to do, because versions should always use the
        // key from the original file. Just create a 1:1 copy and done
        if ($this->isVersion($targetInternalPath) ||
            $this->isVersion($sourceInternalPath)) {
            // remember that we try to create a version so that we can detect it during
            // fopen($sourceInternalPath) and by-pass the encryption in order to
            // create a 1:1 copy of the file
            $this->arrayCache->set('encryption_copy_version_' . $sourceInternalPath, true);
            $result = $this->storage->copyFromStorage($sourceStorage, $sourceInternalPath, $targetInternalPath);
            $this->arrayCache->remove('encryption_copy_version_' . $sourceInternalPath);
            if ($result) {
                $info = $this->getCache('', $sourceStorage)->get($sourceInternalPath);
                // make sure that we update the unencrypted size for the version
                if (isset($info['encrypted']) && $info['encrypted'] === true) {
                    $this->updateUnencryptedSize(
                        $this->getFullPath($targetInternalPath),
                        $info['size']
                    );
                }
                $this->updateEncryptedVersion($sourceStorage, $sourceInternalPath, $targetInternalPath, $isRename);
            }
            return $result;
        }

        // first copy the keys that we reuse the existing file key on the target location
        // and don't create a new one which would break versions for example.
        $mount = $this->mountManager->findByStorageId($sourceStorage->getId());
        if (\count($mount) > 0) {
            // multiple mount points still refer to the same storage, so pick the first
            $mountPoint = $mount[0]->getMountPoint();
            $source = $mountPoint . '/' . $sourceInternalPath;
            $target = $this->getFullPath($targetInternalPath);
            $this->copyKeys($source, $target);
        } else {
            $this->logger->error(\sprintf('Could not find mount point, can\'t keep encryption keys. MountCount: %s', \count($mount)));
        }

        if ($sourceStorage->is_dir($sourceInternalPath)) {
            $dh = $sourceStorage->opendir($sourceInternalPath);
            $result = $this->mkdir($targetInternalPath);
            if (\is_resource($dh)) {
                while ($result and ($file = \readdir($dh)) !== false) {
                    if (!Filesystem::isIgnoredDir($file)) {
                        $result &= $this->copyFromStorage($sourceStorage, $sourceInternalPath . '/' . $file, $targetInternalPath . '/' . $file, false, $isRename);
                    }
                }
            }
        } else {
            try {
                $source = $sourceStorage->fopen($sourceInternalPath, 'r');
                if ($isRename && (\count($mount) > 0)) {
                    $sourceStorageMountPoint = $mount[0]->getMountPoint();
                    $this->sourcePath[$targetInternalPath] = $sourceStorageMountPoint . '/' . $sourceInternalPath;
                } else {
                    unset($this->sourcePath[$targetInternalPath]);
                }
                $target = $this->fopen($targetInternalPath, 'w');
                list(, $result) = \OC_Helper::streamCopy($source, $target);
                \fclose($source);
                \fclose($target);
            } catch (\Exception $e) {
                Encryption::setDisableWriteEncryption(false);
                \fclose($source);
                \fclose($target);
                throw $e;
            }
            if ($result) {
                if ($preserveMtime) {
                    $this->touch($targetInternalPath, $sourceStorage->filemtime($sourceInternalPath));
                }
                if ($sourceStorage->getOwner($sourceInternalPath) === $this->uid
                    || \substr($targetInternalPath, 0, \strlen('files_trashbin/')) !== 'files_trashbin/') {
                    // 1. user1 moves file from home storage to admins's shared folder
                    // 2. user2 grabs the file from admin's shared folder to his own home storage
                    // Admin has a broken copy in his trashbin, which is caused by a wrong encrypted
                    // version stored in the DB. We simply won't update the encrypted version in this
                    // particular case.
                    $this->updateEncryptedVersion($sourceStorage, $sourceInternalPath, $targetInternalPath, $isRename);
                }
            } else {
                // delete partially written target file
                $this->unlink($targetInternalPath);
                // delete cache entry that was created by fopen
                $this->getCache()->remove($targetInternalPath);
            }
        }
        return (bool)$result;
    }

    /**
     * get the path to a local version of the file.
     * The local version of the file can be temporary and doesn't have to be persistent across requests
     *
     * @param string $path
     * @return string
     */
    public function getLocalFile($path) {
        if ($this->encryptionManager->isEnabled()) {
            $cachedFile = $this->getCachedFile($path);
            if (\is_string($cachedFile)) {
                return $cachedFile;
            }
        }
        return $this->storage->getLocalFile($path);
    }

    /**
     * Returns the wrapped storage's value for isLocal()
     *
     * @return bool wrapped storage's isLocal() value
     */
    public function isLocal() {
        if ($this->encryptionManager->isEnabled()) {
            return false;
        }
        return $this->storage->isLocal();
    }

    /**
     * see http://php.net/manual/en/function.stat.php
     * only the following keys are required in the result: size and mtime
     *
     * @param string $path
     * @return array
     */
    public function stat($path) {
        $stat = $this->storage->stat($path);
        $fileSize = $this->filesize($path);
        $stat['size'] = $fileSize;
        $stat[7] = $fileSize;
        return $stat;
    }

    /**
     * see http://php.net/manual/en/function.hash.php
     *
     * @param string $type
     * @param string $path
     * @param bool $raw
     * @return string
     */
    public function hash($type, $path, $raw = false) {
        $fh = $this->fopen($path, 'rb');
        $ctx = \hash_init($type);
        \hash_update_stream($ctx, $fh);
        \fclose($fh);
        return \hash_final($ctx, $raw);
    }

    /**
     * return full path, including mount point
     *
     * @param string $path relative to mount point
     * @return string full path including mount point
     */
    protected function getFullPath($path) {
        return Filesystem::normalizePath($this->mountPoint . '/' . $path);
    }

    /**
     * read first block of encrypted file, typically this will contain the
     * encryption header
     *
     * @param string|resource $path
     * @return string
     */
    protected function readFirstBlock($path) {
        if (\is_resource($path)) {
            $firstBlock = \fread($path, $this->util->getHeaderSize());
            \rewind($path);
            return $firstBlock;
        }
        $firstBlock = '';
        if ($this->storage->file_exists($path)) {
            $handle = $this->storage->fopen($path, 'r');
            $firstBlock = \fread($handle, $this->util->getHeaderSize());
            \fclose($handle);
        }
        return $firstBlock;
    }

    /**
     * return header size of given file
     *
     * @param string|resource $path
     * @return int
     */
    protected function getHeaderSize($path) {
        $headerSize = 0;
        if (!\is_resource($path)) {
            $realFile = OC_Util::stripPartialFileExtension($path);
            if ($this->storage->file_exists($realFile)) {
                $path = $realFile;
            }
        }
        $firstBlock = $this->readFirstBlock($path);

        if (\substr($firstBlock, 0, \strlen(Util::HEADER_START)) === Util::HEADER_START) {
            $headerSize = $this->util->getHeaderSize();
        }

        return $headerSize;
    }

    /**
     * parse raw header to array
     *
     * @param string $rawHeader
     * @return array
     */
    protected function parseRawHeader($rawHeader) {
        $result = [];
        if (\substr($rawHeader, 0, \strlen(Util::HEADER_START)) === Util::HEADER_START) {
            $header = $rawHeader;
            $endAt = \strpos($header, Util::HEADER_END);
            if ($endAt !== false) {
                $header = \substr($header, 0, $endAt + \strlen(Util::HEADER_END));

                // +1 to not start with an ':' which would result in empty element at the beginning
                $exploded = \explode(':', \substr($header, \strlen(Util::HEADER_START)+1));

                $element = \array_shift($exploded);
                while ($element !== Util::HEADER_END) {
                    $result[$element] = \array_shift($exploded);
                    $element = \array_shift($exploded);
                }
            }
        }

        return $result;
    }

    /**
     * read header from file
     *
     * @param string|resource $path
     * @return array
     */
    protected function getHeader($path) {
        if (\is_resource($path)) {
            $exists = false;
        } else {
            $realFile = OC_Util::stripPartialFileExtension($path);
            $exists = $this->storage->file_exists($realFile);
            if ($exists) {
                $path = $realFile;
            }
        }

        $firstBlock = $this->readFirstBlock($path);
        $result = $this->parseRawHeader($firstBlock);

        // if the header doesn't contain a encryption module we check if it is a
        // legacy file. If true, we add the default encryption module
        if (!isset($result[Util::HEADER_ENCRYPTION_MODULE_KEY])) {
            if (!empty($result)) {
                $result[Util::HEADER_ENCRYPTION_MODULE_KEY] = 'OC_DEFAULT_MODULE';
            } elseif ($exists) {
                // if the header was empty we have to check first if it is a encrypted file at all
                // We would do query to filecache only if we know that entry in filecache exists
                $info = $this->getCache()->get($path);
                if (isset($info['encrypted']) && $info['encrypted'] === true) {
                    $result[Util::HEADER_ENCRYPTION_MODULE_KEY] = 'OC_DEFAULT_MODULE';
                }
            }
        }

        return $result;
    }

    /**
     * read encryption module needed to read/write the file located at $path
     *
     * @param string $path
     * @return null|\OCP\Encryption\IEncryptionModule
     * @throws ModuleDoesNotExistsException
     * @throws \Exception
     */
    protected function getEncryptionModule($path) {
        $encryptionModule = null;
        $header = $this->getHeader($path);
        $encryptionModuleId = $this->util->getEncryptionModuleId($header);
        if (!empty($encryptionModuleId)) {
            try {
                $encryptionModule = $this->encryptionManager->getEncryptionModule($encryptionModuleId);
            } catch (ModuleDoesNotExistsException $e) {
                $this->logger->critical('Encryption module defined in "' . $path . '" not loaded!');
                throw $e;
            }
        }
        return $encryptionModule;
    }

    /**
     * @param string $path
     * @param int $unencryptedSize
     */
    public function updateUnencryptedSize($path, $unencryptedSize) {
        $this->unencryptedSize[$path] = $unencryptedSize;
    }

    /**
     * copy keys to new location
     *
     * @param string $source path relative to data/
     * @param string $target path relative to data/
     * @return bool
     */
    protected function copyKeys($source, $target) {
        if (!$this->util->isExcluded($source)) {
            return $this->keyStorage->copyKeys($source, $target);
        }

        return false;
    }

    /**
     *
     * delete file keys of the file
     *
     * @param $path path of the file key to delete
     * @return bool
     */
    protected function deleteAllFileKeys($path) {
        $fullPath = $this->getFullPath($path);
        return $this->keyStorage->deleteAllFileKeys($fullPath);
    }

    /**
     * check if path points to a files version
     *
     * @param $path
     * @return bool
     */
    protected function isVersion($path) {
        $normalized = Filesystem::normalizePath($path);
        return \substr($normalized, 0, \strlen('/files_versions/')) === '/files_versions/';
    }
}