A cool IBE project
I just got back from a great demo of an IBE secured messaging web service, built as a masters practicum project by Nishant Dubay, Anusha Nagarajan, Tyelisa Shields, and Yash Shroff. SAP sponsored the project, which was supervised by Yuecel Karabulut of the SAP Office of the CTO. The basic idea here is that there's a central semi-trusted service that receives messages from a set of "smart devices", which might be water meters, cars, or mobile devices. The devices want to secure messages so that only trusted recipients can read the messages (for example, messages from the water meter should only be read by the water company, and perhaps a usage optimization agency). The devices don't know who the recipients are, so they encrypt the message to an attribute, which is turned directly into an IBE key. Service providers can then go retrieve messages, and authenticate to a key server, which will give them the keys for only their authorized set of attributes. They incorporate nonces so that the server can revoke attributes in case a service provider is no longer trusted to access some attribute.
In a certain way of speaking, IBE isn't really an encryption mechanism, it's a way to turn an access policy (like "This data can only be read by water company employees") directly into a key that can then be used to encrypt data. The value here is that access control is no longer dependent on the behavior of the computers used to store that data (or the backup tapes that data is written to, etc.) but instead on a central key management server. You can now just trust that the web service reliably stores and delivers data, and trust a separate element to keep that data private. The key server that controls privacy can live as a third-party service, or be kept internal to a company. Hopefully, someday, we'll have services like dropbox.com and xdrive.com that will serve up data, but it will stay encrypted in such a way that even a total loss of data by the service doesn't actually disclose any sensitive information. IBE is really elegant, easy way to make that work.
The CMU team is off to build the next version of their service, which might incorporate some of Brent Water's innovative attribute-based encryption work to allow for complex policies that join together multiple attributes. I'm looking forward to seeing what they come up with!