Searching an Encrypted Cloud

Researchers are working on ways to make encrypted data easier to find.

Recent advances in cryptography could mean that future cloud computing services will not only be able to encrypt documents to keep them safe in the cloud--but also make it possible to search and retrieve this information without first decrypting it, researchers say.

Credit: Technology Review

"This will be a challenging endeavor," says Dawn Song, a computer scientist at the University of California, Berkeley, who has made fundamental research contributions to using encrypted search strings to find encrypted documents. "However, some of these recent advances are very powerful and, if cleverly engineered and deployed, could lead to significant advances," in adding security and privacy to cloud computing over the next few years.

At the ACM Cloud Computing Security Workshop in Chicago tomorrow, Microsoft Research will propose a theoretical architecture that would stitch together several cryptographic technologies in various stages of development to make the encrypted cloud more searchable. The basic idea is that cloud users could download software that would encrypt their data before it's sent into the cloud. In addition, the software would issue encrypted strings, called tokens, which can be used to check that documents are intact and--crucially--to search their contents without first having to decrypt them.

While the underlying technologies weren't developed by Microsoft, "we want to show how existing and emerging cryptographic techniques can be combined to make data in the cloud more secure," says Kristin Lauter, head of the Cryptography Group at Microsoft Research, who will describe the proposal tomorrow.

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While cloud computing has exploded in popularity in recent years thanks to the potential efficiency and cost savings of outsourcing the management of data and applications, a few high-profile glitches and hacks have left many potential users worried, and prompted experts to suggest that new technologies may be needed.

For example, early this year, a hacker who guessed the correct answer to a Twitter employee's security question was able to extract all of the documents stored in Twitter's "Google Apps" account. And, in March this year, a software bug led to a foul-up in the sharing privileges of Google Docs. As a result, for a small number of users (a fraction of 1 percent), choosing to share a single document instantly gave that contact access to all other shared documents, too.