Original URL: http://www.theregister.co.uk/2012/04/19/cipherdocs_beta/

CompSci boffins tout file encryption for Google Docs

Plugin scrambles data en route to Chocolate Factory cloud

By John Leyden

Posted in Security, 19th April 2012 11:42 GMT

Computer scientists in Ireland have developed a technology for Google Docs that allows for the "real-time" encryption of data before it is uploaded to the Google servers.

The CipherDocs system, developed by computer scientists at Trinity College, Dublin, is designed so that Google would not have access to the keys necessary to unscramble data held on its systems. The four computer scientists behind the technology are looking to establish a startup based on their work, based on initial seed funding from government agency Enterprise Ireland.

"It [the technology] means that enterprises can finally start to make use of the low-cost Google Apps suite in a serious way with the knowledge that their sensitive data is stored securely on Google's servers," said Hitesh Tewari, of the Department of Computer Science at Trinity College, Dublin.

"We are an early stage startup with four employees and have received €100,000 in funding. Our mission is to provide users and enterprises with simple and transparent encryption products that allow them to make the most out of the cloud computing," he added.

Although the initial connection between a Google Docs and Google's servers is secure, the user data is stored unencrypted on Google servers, leaving it open to viewing for anyone who has or obtains the right level of access. This can pose problems for organisations and individuals that wish to store sensitive information (such as financial data, project plans, patient records etc) in their documents.

The CipherDocs software plugin encrypts user data in "real-time" (ie, as the user is typing into their browser window), prior to it being sent to Google's servers, addressing this problem. The technology is initially available as a Firefox plugin that uses Advanced Encryption Standard (AES-256) to encrypt data.

Although it was initially available only for Word-style document files, the team behind the technology is looking to extend its functionality to support spreadsheets and presentations as well as on browsers including Chrome and Internet Explorer.

The technology already goes beyond simple document encryption. Google Docs lets users share their documents and allows multiple people to collaboratively edit a document. CipherDocs preserves this core functionality and allows for the secure sharing of Google Docs. This is accomplished by "transparently and securely sharing the document encryption key between the intended recipients" through a KeyHub service. A mobile keychain add-on means the user can access their documents from any machine, providing they have the plugin installed.

"In the event a user loses their laptop or the hard disk dies, they do not lose access to their documents," the CipherDocs team explain. "At no point do we have access to user decryption keys as these are at all times protected by a user-chosen master password."

A screenshot of the CipherDocs technology in action from the website (click to enlarge)

A work in progress...

A beta version of the Firefox plugin for CipherDocs is available for download.

"We are currently working on a more stable version of the software which is greatly assisted from feedback received from the beta/trial," Tewari told El Reg. "We are simultaneously working on a paper describing the design with a view to submitting to an appropriate conference/journal for peer review. As a final step, potentially informed by this peer-review process, we hope to attain industry certification in the UK and US from bodies such as CESG and NIST respectively. This will cover both design and implementation."

An FAQ for CipherDocs, dealing with issues of confidentiality and the threat model behind the technology, can be found here (PDF).

A Register contact actively involved in the Jericho Forum, an end-user dominated industry group, gave the technology a cautious welcome. He said that although he was yet to look at the details – and legal issues remain – the general approach seems promising.

"In principle this could be very useful," he said. "Depends on the details of how key management is done. Some systems can work very well for a single user and protect their secrets, but simply don't scale to enterprise use (too many keys, too few keys, keys not in correct hands, etc).

"In practice there may be some legal issues too: do the lawyers and regulators consider such a scheme satisfactory to let it be used to hold sensitive data? Answer is likely to be 'sometimes'."

CipherDocs is not yet enterprise-ready, he added.

"The current version is not aimed at enterprises, just for personal use with some sharing features added. So this has potential to keep your documents secure from the eyes of Google and the FBI and NSA, etc. So long as you have a strong password on your CipherDocs account, and note the various conditions in their FAQ, such as it assumes no man in the browser or man-in-the-middle to Google (as that could be used to modify Google Docs' Javascript). Those issues would generally apply to any such system, so this is not a specific criticism.

"Enterprise versions would need extensions to the key management to permit some form of key escrow, depending on local laws. Regulated industries requiring monitoring of communications would not be able to use it until such facilities were in place.

"So I put this as another positive step on the road to moving security to the data itself, as described in the Jericho Forum commandments. But a long way to go before such data-centric security is pervasive on all types of data."

CipherDocs for DropBox

The CipherDocs team are also planning to develop a version of much the same technology for Dropbox  (details here) and Microsoft Office (here).

CipherDocs for MS Office will come as a plugin that allows for the secure sharing of Office documents such as Word, Excel and PowerPoint files. Users would click on the CipherDocs “Secure Share” icon and enter in the email address of the recipients to securely share a file. The recipients would in turn receive an email from the CipherDocs service that contains a link to the encrypted file that is stored on the CipherDocs servers. Upon clicking the link, the file is downloaded from the server, decrypted and displayed to the user.

CipherDocs for DropBox would come as a plugin that allows for any type or format of files to be stored encrypted within a public DropBox folder. The owner retains access control over which files are shared securely with which users. All that is required to securely share files is to drag and drop the files into the "CipherDocs Enabled" DropBox folder and enter in the recipient's email address. The CipherDocs plugin will take care of the encryption of the files and the transparent sharing of the security keys. ®