server/apps/files_encryption/lib/session.php

<?php
/**
 * ownCloud
 *
 * @author Sam Tuke
 * @copyright 2012 Sam Tuke samtuke@owncloud.com
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or any later version.
 *
 * This library 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 along with this library.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

namespace OCA\Encryption;

/**
 * Class for handling encryption related session data
 */

class Session
{

	private $view;

	/**
	 * @brief if session is started, check if ownCloud key pair is set up, if not create it
	 * @param \OC_FilesystemView $view
	 *
	 * @note The ownCloud key pair is used to allow public link sharing even if encryption is enabled
	 */
	public function __construct( $view ) {

		$this->view = $view;

		if ( !$this->view->is_dir( 'owncloud_private_key' ) ) {

			$this->view->mkdir( 'owncloud_private_key' );

		}

		$publicShareKeyId = \OC_Appconfig::getValue( 'files_encryption', 'publicShareKeyId' );

		if ( $publicShareKeyId === null ) {
			$publicShareKeyId = 'pubShare_' . substr( md5( time() ), 0, 8 );
			\OC_Appconfig::setValue( 'files_encryption', 'publicShareKeyId', $publicShareKeyId );
		}

		if (
			!$this->view->file_exists( "/public-keys/" . $publicShareKeyId . ".public.key" )
			|| !$this->view->file_exists( "/owncloud_private_key/" . $publicShareKeyId . ".private.key" )
		) {

			$keypair = Crypt::createKeypair();

			// Disable encryption proxy to prevent recursive calls
			$proxyStatus = \OC_FileProxy::$enabled;
			\OC_FileProxy::$enabled = false;

			// Save public key

			if ( !$view->is_dir( '/public-keys' ) ) {
				$view->mkdir( '/public-keys' );
			}

			$this->view->file_put_contents( '/public-keys/' . $publicShareKeyId . '.public.key', $keypair['publicKey'] );

			// Encrypt private key empty passphrase
			$encryptedPrivateKey = Crypt::symmetricEncryptFileContent( $keypair['privateKey'], '' );

			// Save private key
			$this->view->file_put_contents( '/owncloud_private_key/' . $publicShareKeyId . '.private.key', $encryptedPrivateKey );

			\OC_FileProxy::$enabled = $proxyStatus;

		}

		if ( \OCP\USER::getUser() === false ||
			( isset( $_GET['service'] ) && $_GET['service'] == 'files' &&
				isset( $_GET['t'] ) )
		) {
			// Disable encryption proxy to prevent recursive calls
			$proxyStatus = \OC_FileProxy::$enabled;
			\OC_FileProxy::$enabled = false;

			$encryptedKey = $this->view->file_get_contents( '/owncloud_private_key/' . $publicShareKeyId . '.private.key' );
			$privateKey = Crypt::symmetricDecryptFileContent( $encryptedKey, '' );
			$this->setPrivateKey( $privateKey );

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

	/**
	 * @brief Sets user private key to session
	 * @param string $privateKey
	 * @return bool
	 */
	public function setPrivateKey( $privateKey ) {

		$_SESSION['privateKey'] = $privateKey;

		return true;

	}

	/**
	 * @brief Gets user private key from session
	 * @returns string $privateKey The user's plaintext private key
	 *
	 */
	public function getPrivateKey() {

		if (
			isset( $_SESSION['privateKey'] )
			&& !empty( $_SESSION['privateKey'] )
		) {

			return $_SESSION['privateKey'];

		} else {

			return false;

		}

	}

	/**
	 * @brief Sets user legacy key to session
	 * @param $legacyKey
	 * @return bool
	 */
	public function setLegacyKey( $legacyKey ) {

		$_SESSION['legacyKey'] = $legacyKey;

		return true;
	}

	/**
	 * @brief Gets user legacy key from session
	 * @returns string $legacyKey The user's plaintext legacy key
	 *
	 */
	public function getLegacyKey() {

		if (
			isset( $_SESSION['legacyKey'] )
			&& !empty( $_SESSION['legacyKey'] )
		) {

			return $_SESSION['legacyKey'];

		} else {

			return false;

		}

	}

}