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Sync Your Files without Trusting the Cloud

The company behind the Bittorrent protocol is working on software that can replicate most features of file-syncing services without handing your data to cloud servers.
January 17, 2014

The debate over how much we should trust cloud companies with our data (see “NSA Spying Is Making Us Less Safe”) was reawakened last year after revelations that the National Security Agency routinely harvests data from Internet companies including Google, Microsoft, Yahoo, and Facebook.

Bittorrent cloud storage
Data dump: New software from Bittorrent can synchronize files between computers and mobile devices without ever storing them in a data center like this one.

Bittorrent, the company behind the sometimes controversial file-sharing protocol of the same name, is hoping that this debate will drive adoption of its new file-syncing technology this year. Called Bittorrent Sync, it synchronizes folders and files on different computers and mobile devices in a way that’s similar to what services like Dropbox offer, but without ever copying data to a central cloud server.

Cloud-based file-syncing services like Dropbox and Microsoft’s SkyDrive route all data via their own servers and keep a copy of it there. The Bittorrent software instead has devices contact one another directly over the Internet to update files as they are added or changed.

That difference in design means that people using Bittorrent Sync don’t have to worry about whether the cloud company hosting their data is properly securing it against rogue employees or other threats.

Forgoing the cloud also means that data shared using Bittorrent Sync could be harvested by the NSA or another agency only by going directly to the person or company controlling the synced devices. Synced data does travel over the public Internet, where it might be intercepted by a surveillance agency such as the NSA, which is known to collect data directly from the Internet backbone, but it travels in a strongly encrypted form. One drawback of Bittorrent Sync’s design is that two devices must both be online at the same time for them to synchronize, since there’s no intermediary server to act as an always-on source.

Bittorrent Sync is available now as a free download for PCs and mobile devices, but in a beta version that lacks the polish and ease of use of many consumer applications. Bittorrent CEO Eric Klinker says the next version, due this spring, will feature major upgrades to the interface that will make the software more user friendly and in line with its established cloud-based competitors.

Klinker says Bittorrent Sync shows how popular applications of the Internet can be designed in a way that gives people control of their own data, despite prevailing trends. “Pick any app on the Web today, it could be Twitter, e-mail, search, and it has been developed in a very centralized way—those businesses are built around centralizing information on their servers,” he says. “I’m trying to put more power in the hands of the end user and less in the hands of these companies and other centralizing authorities.”

Anonymous data sent back to Bittorrent by its software indicates that more than two million people are already using it each month. Some of those people have found uses that go beyond just managing files. For example, the company says one author in Beijing uses Bittorrent Sync to distribute blog posts on topics sensitive with Chinese authorities. And one U.S. programmer built a secure, decentralized messaging system on top of the software.

Klinker says that companies are also starting to use Bittorrent Sync to keep data inside their own systems or to avoid the costs of cloud-based solutions. He plans to eventually make Bittorrent Sync pay for itself by finding a way to sell extra services to corporate users of the software.

Given its emphasis on transparency and data ownership, Bittorrent has been criticized by some for not releasing the source code for its application. Some in the tech- and privacy-savvy crowd attracted by Bittorrent Sync’s decentralized design say this step is necessary if people are to be sure that no privacy-compromising bugs or backdoors are hiding in the software.

Klinker says he understands those concerns and may yet decide to release the source code for the software. “It’s a fair point, and we understand that transparency is good, but it opens up vulnerabilities, too,” he says. For now the company prefers to keep the code private and perform security audits behind closed doors, says Klinker.

Jacob Williams, a digital forensic scientist with CSR Group, says that stance is defensible, although he generally considers open-source programs to be more secure than those that aren’t. “Open source is a double-edged sword,” says Williams, because finding subtly placed vulnerabilities is very challenging, and because open-source projects can be split off into different versions, which dilutes the number of people looking at any one version.

Williams’s own research has shown how Dropbox and similar services could be used to slip malicious software through corporate firewalls because they are configured to use the same route as Web traffic, which usually gets a free pass (see “Dropbox Can Sync Malware”). Bittorrent Sync is configured slightly differently, he says, and so likely doesn’t automatically open up an open channel to the Internet. However, “Bittorrent Sync will likely require changes to the firewall in any moderately secure network,” he notes.

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