Editing Aggregation of sensitive data (section)

==Introduction==
When Diffie and Hellman introduced public-key cryptography in the mid-nineteen seventies, it was clear that beyond its mathematical interest, it would have a huge effect on real-world data processing. This intuition was largely proven to be true. As information flows in networks, the security of the data deeply affects the trust relationship between the communicating participants. For example, online payment would not exist if the buyer did not trust that its data are correctly secured. It is not exaggerating to state that cryptography is a key ingredient of the modern information society.

These issues became more and more important since we have realized the value of data. Collecting data securely requires careful application of cryptographic techniques. But data owners also want to be able to capitalize on them, and computing over data while maintaining privacy requires techniques that are at the forefront of modern cryptographic research.

Issues arise even from simple problems such as extracting statistics from distributed data. The data might be too valuable or regulated in a way that prevents sending them directly to a third party.

Classical cryptography offers solutions to perform these operations. In particular, secure multiparty computing allows mistrustful parties to compute over their inputs while maintaining privacy. Some secure computing solutions also involve third parties but the theory ensures that they will not get any information during the process.