Researchers at Microsoft Research Silicon Valley are developing a mobile network called "Contrail," that enables users to share media without sharing information with central server. Contrail runs on Microsoft's cloud computing service, Windows Azure, and the team has developed three compatible applications running on HTC Windows Mobile cell phones.
"With Contrail, central location doesn't ever know my information, or what particular users care about--it just sees encrypted stuff to pass on." When a Contrail user updates his information on network, by adding a new photo, for e.g., the image file is sent to a server operating within networks' cloud, just as with a conventional social network. But it's encrypted and appended with a list that specifies which other users are allowed to see the file. When those users' devices check in with the social network, they download the data and decrypt it to reveal the photo.
Contrail requires users to opt-in if they want to receive information from friends. When a person wants to receive a particular kind of update from a contact, a "filter" is sent to that friend's device. If, for example, a mother wants to see all the photos tagged with the word "family" by her son, she creates the filter on her phone. The filter is encrypted and sent via the cloud to her son's device."