Homomorphic encryption

Homomorphic encryption is a form of encryption that allows computations to be performed on encrypted data without first having to decrypt it. The result of the computations are left in an encrypted form which, when decrypted, result in an output that is identical to that of the operations performed on the unencrypted data. Homomorphic encryption can be used for privacy-preserving outsourced storage and computation. This allows data to be encrypted and outsourced to commercial cloud environments for processing, all while encrypted.

As an example of a practical application of homomorphic encryption: photographs can be scanned for regions of interest (ROI), the encrypted values of which are then compared to precomputed ROI of points of (touristical) interest, without revealing the contents of a photo. However, observation of side-channels can see a photograph being sent to a point-of-interest lookup service, revealing the fact that photographs were taken.

Thus, homomorphic encryption eliminates the need for processing data in the clear, thereby preventing attacks that would enable an attacker to access that data while it is being processed, using privilege escalation.

For sensitive data, such as healthcare information, homomorphic encryption can be used to enable new services by removing privacy barriers inhibiting data sharing or increasing security to existing services. For example, predictive analytics in healthcare can be hard to apply via a third-party service provider due to medical data privacy concerns. But if the predictive-analytics service provider could operate on encrypted data instead, without having the decryption keys, these privacy concerns are diminished.