server/apps/files_encryption/ajax/changeRecoveryPassword.php

<?php

/**
 * Copyright (c) 2013, Bjoern Schiessle <schiessle@owncloud.com>
 * This file is licensed under the Affero General Public License version 3 or later.
 * See the COPYING-README file.
 *
 * Script to change recovery key password
 *
 */

use OCA\Encryption;

\OCP\JSON::checkAdminUser();
\OCP\JSON::checkAppEnabled('files_encryption');
\OCP\JSON::callCheck();

$l = \OC::$server->getL10N('core');

$return = false;

$oldPassword = $_POST['oldPassword'];
$newPassword = $_POST['newPassword'];

$view = new \OC\Files\View('/');
$util = new \OCA\Encryption\Util(new \OC\Files\View('/'), \OCP\User::getUser());

$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;

$keyId = $util->getRecoveryKeyId();
$keyPath = '/owncloud_private_key/' . $keyId . '.private.key';

$encryptedRecoveryKey = $view->file_get_contents($keyPath);
$decryptedRecoveryKey = \OCA\Encryption\Crypt::decryptPrivateKey($encryptedRecoveryKey, $oldPassword);

if ($decryptedRecoveryKey) {
	$cipher = \OCA\Encryption\Helper::getCipher();
	$encryptedKey = \OCA\Encryption\Crypt::symmetricEncryptFileContent($decryptedRecoveryKey, $newPassword, $cipher);
	if ($encryptedKey) {
		\OCA\Encryption\Keymanager::setPrivateSystemKey($encryptedKey, $keyId . '.private.key');
		$return = true;
	}
}

\OC_FileProxy::$enabled = $proxyStatus;

// success or failure
if ($return) {
	\OCP\JSON::success(array('data' => array('message' => $l->t('Password successfully changed.'))));
} else {
	\OCP\JSON::error(array('data' => array('message' => $l->t('Could not change the password. Maybe the old password was not correct.'))));
}