Current File : /www/varak.net/nextcloud.varak.net/apps/encryption/lib/Crypto/Encryption.php
<?php
/**
* SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
* SPDX-FileCopyrightText: 2016 ownCloud, Inc.
* SPDX-License-Identifier: AGPL-3.0-only
*/
namespace OCA\Encryption\Crypto;
use OC\Encryption\Exceptions\DecryptionFailedException;
use OC\Files\Cache\Scanner;
use OC\Files\View;
use OCA\Encryption\Exceptions\PublicKeyMissingException;
use OCA\Encryption\KeyManager;
use OCA\Encryption\Session;
use OCA\Encryption\Util;
use OCP\Encryption\IEncryptionModule;
use OCP\IL10N;
use Psr\Log\LoggerInterface;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Output\OutputInterface;
class Encryption implements IEncryptionModule {
public const ID = 'OC_DEFAULT_MODULE';
public const DISPLAY_NAME = 'Default encryption module';
/** @var string */
private $cipher;
/** @var string */
private $path;
/** @var string */
private $user;
private array $owner;
/** @var string */
private $fileKey;
/** @var string */
private $writeCache;
/** @var array */
private $accessList;
/** @var boolean */
private $isWriteOperation;
private bool $useMasterPassword;
private bool $useLegacyBase64Encoding = false;
/** @var int Current version of the file */
private int $version = 0;
/** @var array remember encryption signature version */
private static $rememberVersion = [];
public function __construct(
private Crypt $crypt,
private KeyManager $keyManager,
private Util $util,
private Session $session,
private EncryptAll $encryptAll,
private DecryptAll $decryptAll,
private LoggerInterface $logger,
private IL10N $l,
) {
$this->owner = [];
$this->useMasterPassword = $this->util->isMasterKeyEnabled();
}
/**
* @return string defining the technical unique id
*/
public function getId() {
return self::ID;
}
/**
* In comparison to getKey() this function returns a human readable (maybe translated) name
*
* @return string
*/
public function getDisplayName() {
return self::DISPLAY_NAME;
}
/**
* 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
* @param string $user who read/write the file
* @param string $mode php stream open mode
* @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'
*
* @return array $header contain data as key-value pairs which should be
* written to the header, in case of a write operation
* or if no additional data is needed return a empty array
*/
public function begin($path, $user, $mode, array $header, array $accessList) {
$this->path = $this->getPathToRealFile($path);
$this->accessList = $accessList;
$this->user = $user;
$this->isWriteOperation = false;
$this->writeCache = '';
$this->useLegacyBase64Encoding = true;
if (isset($header['encoding'])) {
$this->useLegacyBase64Encoding = $header['encoding'] !== Crypt::BINARY_ENCODING_FORMAT;
}
if ($this->session->isReady() === false) {
// if the master key is enabled we can initialize encryption
// with a empty password and user name
if ($this->util->isMasterKeyEnabled()) {
$this->keyManager->init('', '');
}
}
/* If useLegacyFileKey is not specified in header, auto-detect, to be safe */
$useLegacyFileKey = (($header['useLegacyFileKey'] ?? '') == 'false' ? false : null);
$this->fileKey = $this->keyManager->getFileKey($this->path, $this->user, $useLegacyFileKey, $this->session->decryptAllModeActivated());
// 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) {
$this->cipher = $this->crypt->getCipher();
$this->useLegacyBase64Encoding = $this->crypt->useLegacyBase64Encoding();
} elseif (isset($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();
}
$result = [
'cipher' => $this->cipher,
'signed' => 'true',
'useLegacyFileKey' => 'false',
];
if ($this->useLegacyBase64Encoding !== true) {
$result['encoding'] = Crypt::BINARY_ENCODING_FORMAT;
}
return $result;
}
/**
* 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 string $position
* @return string remained data which should be written to the file in case
* of a write operation
* @throws PublicKeyMissingException
* @throws \Exception
* @throws \OCA\Encryption\Exceptions\MultiKeyEncryptException
*/
public function end($path, $position = '0') {
$result = '';
if ($this->isWriteOperation) {
// 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)] = $this->version + 1;
}
if (!empty($this->writeCache)) {
$result = $this->crypt->symmetricEncryptFileContent($this->writeCache, $this->fileKey, $this->version + 1, $position);
$this->writeCache = '';
}
$publicKeys = [];
if ($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;
}
}
}
}
$publicKeys = $this->keyManager->addSystemKeys($this->accessList, $publicKeys, $this->getOwner($path));
$shareKeys = $this->crypt->multiKeyEncrypt($this->fileKey, $publicKeys);
if (!$this->keyManager->deleteLegacyFileKey($this->path)) {
$this->logger->warning(
'Failed to delete legacy filekey for {path}',
['app' => 'encryption', 'path' => $path]
);
}
foreach ($shareKeys as $uid => $keyFile) {
$this->keyManager->setShareKey($this->path, $uid, $keyFile);
}
}
return $result ?: '';
}
/**
* encrypt data
*
* @param string $data you want to encrypt
* @param int $position
* @return string encrypted data
*/
public function encrypt($data, $position = 0) {
// If extra data is left over from the last round, make sure it
// is integrated into the next block
if ($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 unencrypted block
if ($remainingLength < $this->getUnencryptedBlockSize(true)) {
// 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->getUnencryptedBlockSize(true));
$encrypted .= $this->crypt->symmetricEncryptFileContent($chunk, $this->fileKey, $this->version + 1, (string)$position);
// 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->getUnencryptedBlockSize(true));
}
}
return $encrypted;
}
/**
* decrypt data
*
* @param string $data you want to decrypt
* @param int|string $position
* @return string decrypted data
* @throws DecryptionFailedException
*/
public function decrypt($data, $position = 0) {
if (empty($this->fileKey)) {
$msg = 'Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.';
$hint = $this->l->t('Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.');
$this->logger->error($msg);
throw new DecryptionFailedException($msg, $hint);
}
return $this->crypt->symmetricDecryptFileContent($data, $this->fileKey, $this->cipher, $this->version, $position, !$this->useLegacyBase64Encoding);
}
/**
* update encrypted file, e.g. give additional users access to the file
*
* @param string $path path to the file which should be updated
* @param string $uid of the user who performs the operation
* @param array $accessList who has access to the file contains the key 'users' and 'public'
* @return bool
*/
public function update($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 false;
}
$fileKey = $this->keyManager->getFileKey($path, $uid, null);
if (!empty($fileKey)) {
$publicKeys = [];
if ($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());
}
}
}
$publicKeys = $this->keyManager->addSystemKeys($accessList, $publicKeys, $this->getOwner($path));
$shareKeys = $this->crypt->multiKeyEncrypt($fileKey, $publicKeys);
$this->keyManager->deleteAllFileKeys($path);
foreach ($shareKeys as $uid => $keyFile) {
$this->keyManager->setShareKey($path, $uid, $keyFile);
}
} else {
$this->logger->debug('no file key found, we assume that the file "{file}" is not encrypted',
['file' => $path, 'app' => 'encryption']);
return false;
}
return true;
}
/**
* 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 && $storage->instanceOfStorage('\OCP\Files\IHomeStorage')) {
return false;
}
}
$parts = explode('/', $path);
if (count($parts) < 4) {
return false;
}
if ($parts[2] === 'files') {
return true;
}
if ($parts[2] === 'files_versions') {
return true;
}
if ($parts[2] === 'files_trashbin') {
return true;
}
return false;
}
/**
* get size of the unencrypted payload per block.
* Nextcloud read/write files with a block size of 8192 byte
*
* Encrypted blocks have a 22-byte IV and 2 bytes of padding, encrypted and
* signed blocks have also a 71-byte signature and 1 more byte of padding,
* resulting respectively in:
*
* 8192 - 22 - 2 = 8168 bytes in each unsigned unencrypted block
* 8192 - 22 - 2 - 71 - 1 = 8096 bytes in each signed unencrypted block
*
* Legacy base64 encoding then reduces the available size by a 3/4 factor:
*
* 8168 * (3/4) = 6126 bytes in each base64-encoded unsigned unencrypted block
* 8096 * (3/4) = 6072 bytes in each base64-encoded signed unencrypted block
*
* @param bool $signed
* @return int
*/
public function getUnencryptedBlockSize($signed = false) {
if ($this->useLegacyBase64Encoding) {
return $signed ? 6072 : 6126;
} else {
return $signed ? 8096 : 8168;
}
}
/**
* 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, $uid, null);
if (empty($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('Cannot 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;
}
/**
* 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);
}
/**
* 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);
}
/**
* @param string $path
* @return string
*/
protected function getPathToRealFile($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;
}
/**
* get owner of a file
*
* @param string $path
* @return string
*/
protected function getOwner($path) {
if (!isset($this->owner[$path])) {
$this->owner[$path] = $this->util->getOwner($path);
}
return $this->owner[$path];
}
/**
* Check if the module is ready to be used by that specific user.
* In case a module is not ready - because e.g. key pairs have not been generated
* upon login this method can return false before any operation starts and might
* cause issues during operations.
*
* @param string $user
* @return boolean
* @since 9.1.0
*/
public function isReadyForUser($user) {
if ($this->util->isMasterKeyEnabled()) {
return true;
}
return $this->keyManager->userHasKeys($user);
}
/**
* We only need a detailed access list if the master key is not enabled
*
* @return bool
*/
public function needDetailedAccessList() {
return !$this->util->isMasterKeyEnabled();
}
}
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