nextcloud/apps/encryption/lib/crypto/encryption.php

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<?php
/**
* @author Björn Schießle <schiessle@owncloud.com>
* @author Clark Tomlinson <fallen013@gmail.com>
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* @author Jan-Christoph Borchardt <hey@jancborchardt.net>
* @author Joas Schilling <nickvergessen@owncloud.com>
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* @author Lukas Reschke <lukas@owncloud.com>
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* @author Thomas Müller <thomas.mueller@tmit.eu>
*
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* @copyright Copyright (c) 2016, ownCloud, Inc.
* @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/>
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*
*/
namespace OCA\Encryption\Crypto;
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use OC\Encryption\Exceptions\DecryptionFailedException;
use OC\Files\Cache\Scanner;
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use OC\Files\View;
use OCA\Encryption\Exceptions\PublicKeyMissingException;
use OCA\Encryption\Session;
use OCA\Encryption\Util;
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use OCP\Encryption\IEncryptionModule;
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use OCA\Encryption\KeyManager;
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use OCP\IL10N;
use OCP\ILogger;
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use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;
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class Encryption implements IEncryptionModule {
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const ID = 'OC_DEFAULT_MODULE';
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const DISPLAY_NAME = 'Default encryption module';
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/**
* @var Crypt
*/
private $crypt;
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/** @var string */
private $cipher;
/** @var string */
private $path;
/** @var string */
private $user;
/** @var string */
private $fileKey;
/** @var string */
private $writeCache;
/** @var KeyManager */
private $keyManager;
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/** @var array */
private $accessList;
/** @var boolean */
private $isWriteOperation;
/** @var Util */
private $util;
/** @var Session */
private $session;
/** @var ILogger */
private $logger;
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/** @var IL10N */
private $l;
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/** @var EncryptAll */
private $encryptAll;
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/** @var bool */
private $useMasterPassword;
/** @var DecryptAll */
private $decryptAll;
/** @var int unencrypted block size if block contains signature */
private $unencryptedBlockSizeSigned = 6072;
/** @var int unencrypted block size */
private $unencryptedBlockSize = 6126;
/** @var int Current version of the file */
private $version = 0;
/** @var array remember encryption signature version */
private static $rememberVersion = [];
/**
*
* @param Crypt $crypt
* @param KeyManager $keyManager
* @param Util $util
* @param Session $session
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* @param EncryptAll $encryptAll
* @param DecryptAll $decryptAll
* @param ILogger $logger
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* @param IL10N $il10n
*/
public function __construct(Crypt $crypt,
KeyManager $keyManager,
Util $util,
Session $session,
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EncryptAll $encryptAll,
DecryptAll $decryptAll,
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ILogger $logger,
IL10N $il10n) {
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$this->crypt = $crypt;
$this->keyManager = $keyManager;
$this->util = $util;
$this->session = $session;
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$this->encryptAll = $encryptAll;
$this->decryptAll = $decryptAll;
$this->logger = $logger;
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$this->l = $il10n;
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$this->useMasterPassword = $util->isMasterKeyEnabled();
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}
/**
* @return string defining the technical unique id
*/
public function getId() {
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return self::ID;
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}
/**
* In comparison to getKey() this function returns a human readable (maybe translated) name
*
* @return string
*/
public function getDisplayName() {
return self::DISPLAY_NAME;
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}
/**
* start receiving chunks from a file. This is the place where you can
* perform some initial step before starting encrypting/decrypting the
* chunks
*
* @param string $path to the file
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* @param string $user who read/write the file
* @param string $mode php stream open mode
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* @param array $header contains the header data read from the file
* @param array $accessList who has access to the file contains the key 'users' and 'public'
*
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* @return array $header contain data as key-value pairs which should be
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* written to the header, in case of a write operation
* or if no additional data is needed return a empty array
*/
public function begin($path, $user, $mode, array $header, array $accessList) {
$this->path = $this->getPathToRealFile($path);
$this->accessList = $accessList;
$this->user = $user;
$this->isWriteOperation = false;
$this->writeCache = '';
if ($this->session->decryptAllModeActivated()) {
$encryptedFileKey = $this->keyManager->getEncryptedFileKey($this->path);
$shareKey = $this->keyManager->getShareKey($this->path, $this->session->getDecryptAllUid());
$this->fileKey = $this->crypt->multiKeyDecrypt($encryptedFileKey,
$shareKey,
$this->session->getDecryptAllKey());
} else {
$this->fileKey = $this->keyManager->getFileKey($this->path, $this->user);
}
// always use the version from the original file, also part files
// need to have a correct version number if they get moved over to the
// final location
$this->version = (int)$this->keyManager->getVersion($this->stripPartFileExtension($path), new View());
if (
$mode === 'w'
|| $mode === 'w+'
|| $mode === 'wb'
|| $mode === 'wb+'
) {
$this->isWriteOperation = true;
if (empty($this->fileKey)) {
$this->fileKey = $this->crypt->generateFileKey();
}
} else {
// if we read a part file we need to increase the version by 1
// because the version number was also increased by writing
// the part file
if(Scanner::isPartialFile($path)) {
$this->version = $this->version + 1;
}
}
if ($this->isWriteOperation) {
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$this->cipher = $this->crypt->getCipher();
} elseif (isset($header['cipher'])) {
$this->cipher = $header['cipher'];
} else {
// if we read a file without a header we fall-back to the legacy cipher
// which was used in <=oC6
$this->cipher = $this->crypt->getLegacyCipher();
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}
return array('cipher' => $this->cipher, 'signed' => 'true');
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}
/**
* last chunk received. This is the place where you can perform some final
* operation and return some remaining data if something is left in your
* buffer.
*
* @param string $path to the file
* @param int $position
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* @return string remained data which should be written to the file in case
* of a write operation
* @throws PublicKeyMissingException
* @throws \Exception
* @throws \OCA\Encryption\Exceptions\MultiKeyEncryptException
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*/
public function end($path, $position = 0) {
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$result = '';
if ($this->isWriteOperation) {
$this->keyManager->setVersion($path, $this->version + 1, new View());
// in case of a part file we remember the new signature versions
// the version will be set later on update.
// This way we make sure that other apps listening to the pre-hooks
// still get the old version which should be the correct value for them
if (Scanner::isPartialFile($path)) {
self::$rememberVersion[$this->stripPartFileExtension($path)] = $this->version + 1;
}
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if (!empty($this->writeCache)) {
$result = $this->crypt->symmetricEncryptFileContent($this->writeCache, $this->fileKey, $this->version + 1, $position);
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$this->writeCache = '';
}
$publicKeys = array();
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if ($this->useMasterPassword === true) {
$publicKeys[$this->keyManager->getMasterKeyId()] = $this->keyManager->getPublicMasterKey();
} else {
foreach ($this->accessList['users'] as $uid) {
try {
$publicKeys[$uid] = $this->keyManager->getPublicKey($uid);
} catch (PublicKeyMissingException $e) {
$this->logger->warning(
'no public key found for user "{uid}", user will not be able to read the file',
['app' => 'encryption', 'uid' => $uid]
);
// if the public key of the owner is missing we should fail
if ($uid === $this->user) {
throw $e;
}
}
}
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}
$publicKeys = $this->keyManager->addSystemKeys($this->accessList, $publicKeys, $this->user);
$encryptedKeyfiles = $this->crypt->multiKeyEncrypt($this->fileKey, $publicKeys);
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$this->keyManager->setAllFileKeys($this->path, $encryptedKeyfiles);
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}
return $result;
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}
/**
* encrypt data
*
* @param string $data you want to encrypt
* @param int $position
* @return string encrypted data
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*/
public function encrypt($data, $position = 0) {
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// If extra data is left over from the last round, make sure it
// is integrated into the next block
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if ($this->writeCache) {
// Concat writeCache to start of $data
$data = $this->writeCache . $data;
// Clear the write cache, ready for reuse - it has been
// flushed and its old contents processed
$this->writeCache = '';
}
$encrypted = '';
// While there still remains some data to be processed & written
while (strlen($data) > 0) {
// Remaining length for this iteration, not of the
// entire file (may be greater than 8192 bytes)
$remainingLength = strlen($data);
// If data remaining to be written is less than the
// size of 1 6126 byte block
if ($remainingLength < $this->unencryptedBlockSizeSigned) {
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// Set writeCache to contents of $data
// The writeCache will be carried over to the
// next write round, and added to the start of
// $data to ensure that written blocks are
// always the correct length. If there is still
// data in writeCache after the writing round
// has finished, then the data will be written
// to disk by $this->flush().
$this->writeCache = $data;
// Clear $data ready for next round
$data = '';
} else {
// Read the chunk from the start of $data
$chunk = substr($data, 0, $this->unencryptedBlockSizeSigned);
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$encrypted .= $this->crypt->symmetricEncryptFileContent($chunk, $this->fileKey, $this->version + 1, $position);
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// Remove the chunk we just processed from
// $data, leaving only unprocessed data in $data
// var, for handling on the next round
$data = substr($data, $this->unencryptedBlockSizeSigned);
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}
}
return $encrypted;
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}
/**
* decrypt data
*
* @param string $data you want to decrypt
* @param int $position
* @return string decrypted data
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* @throws DecryptionFailedException
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*/
public function decrypt($data, $position = 0) {
if (empty($this->fileKey)) {
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$msg = 'Can not decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.';
$hint = $this->l->t('Can not decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.');
$this->logger->error($msg);
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throw new DecryptionFailedException($msg, $hint);
}
return $this->crypt->symmetricDecryptFileContent($data, $this->fileKey, $this->cipher, $this->version, $position);
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}
/**
* update encrypted file, e.g. give additional users access to the file
*
* @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 $accessList who has access to the file contains the key 'users' and 'public'
* @return boolean
*/
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public function update($path, $uid, array $accessList) {
if (empty($accessList)) {
if (isset(self::$rememberVersion[$path])) {
$this->keyManager->setVersion($path, self::$rememberVersion[$path], new View());
unset(self::$rememberVersion[$path]);
}
return;
}
$fileKey = $this->keyManager->getFileKey($path, $uid);
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if (!empty($fileKey)) {
$publicKeys = array();
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if ($this->useMasterPassword === true) {
$publicKeys[$this->keyManager->getMasterKeyId()] = $this->keyManager->getPublicMasterKey();
} else {
foreach ($accessList['users'] as $user) {
try {
$publicKeys[$user] = $this->keyManager->getPublicKey($user);
} catch (PublicKeyMissingException $e) {
$this->logger->warning('Could not encrypt file for ' . $user . ': ' . $e->getMessage());
}
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}
}
$publicKeys = $this->keyManager->addSystemKeys($accessList, $publicKeys, $uid);
$encryptedFileKey = $this->crypt->multiKeyEncrypt($fileKey, $publicKeys);
$this->keyManager->deleteAllFileKeys($path);
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$this->keyManager->setAllFileKeys($path, $encryptedFileKey);
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} else {
$this->logger->debug('no file key found, we assume that the file "{file}" is not encrypted',
array('file' => $path, 'app' => 'encryption'));
return false;
}
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return true;
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}
/**
* should the file be encrypted or not
*
* @param string $path
* @return boolean
*/
public function shouldEncrypt($path) {
if ($this->util->shouldEncryptHomeStorage() === false) {
$storage = $this->util->getStorage($path);
if ($storage->instanceOfStorage('\OCP\Files\IHomeStorage')) {
return false;
}
}
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$parts = explode('/', $path);
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if (count($parts) < 4) {
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return false;
}
if ($parts[2] == 'files') {
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return true;
}
if ($parts[2] == 'files_versions') {
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return true;
}
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if ($parts[2] == 'files_trashbin') {
return true;
}
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return false;
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}
/**
* get size of the unencrypted payload per block.
* ownCloud read/write files with a block size of 8192 byte
*
* @param bool $signed
* @return int
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*/
public function getUnencryptedBlockSize($signed = false) {
if ($signed === false) {
return $this->unencryptedBlockSize;
}
return $this->unencryptedBlockSizeSigned;
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}
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/**
* check if the encryption module is able to read the file,
* e.g. if all encryption keys exists
*
* @param string $path
* @param string $uid user for whom we want to check if he can read the file
* @return bool
* @throws DecryptionFailedException
*/
public function isReadable($path, $uid) {
$fileKey = $this->keyManager->getFileKey($path, $uid);
if (empty($fileKey)) {
$owner = $this->util->getOwner($path);
if ($owner !== $uid) {
// if it is a shared file we throw a exception with a useful
// error message because in this case it means that the file was
// shared with the user at a point where the user didn't had a
// valid private/public key
$msg = 'Encryption module "' . $this->getDisplayName() .
'" is not able to read ' . $path;
$hint = $this->l->t('Can not read this file, probably this is a shared file. Please ask the file owner to reshare the file with you.');
$this->logger->warning($msg);
throw new DecryptionFailedException($msg, $hint);
}
return false;
}
return true;
}
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/**
* Initial encryption of all files
*
* @param InputInterface $input
* @param OutputInterface $output write some status information to the terminal during encryption
*/
public function encryptAll(InputInterface $input, OutputInterface $output) {
$this->encryptAll->encryptAll($input, $output);
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}
/**
* prepare module to perform decrypt all operation
*
* @param InputInterface $input
* @param OutputInterface $output
* @param string $user
* @return bool
*/
public function prepareDecryptAll(InputInterface $input, OutputInterface $output, $user = '') {
return $this->decryptAll->prepare($input, $output, $user);
}
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/**
* @param string $path
* @return string
*/
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protected function getPathToRealFile($path) {
$realPath = $path;
$parts = explode('/', $path);
if ($parts[2] === 'files_versions') {
$realPath = '/' . $parts[1] . '/files/' . implode('/', array_slice($parts, 3));
$length = strrpos($realPath, '.');
$realPath = substr($realPath, 0, $length);
}
return $realPath;
}
/**
* remove .part file extension and the ocTransferId from the file to get the
* original file name
*
* @param string $path
* @return string
*/
protected function stripPartFileExtension($path) {
if (pathinfo($path, PATHINFO_EXTENSION) === 'part') {
$pos = strrpos($path, '.', -6);
$path = substr($path, 0, $pos);
}
return $path;
}
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}