A hospital that wants to use a cloud computing service to perform artificial intelligence data analysis on sensitive patient records needs a guarantee those data will remain private during computation. Homomorphic encryption is a special type of security scheme that can provide this assurance.

The technique encrypts data in a way that anyone can perform computations without decrypting the data, preventing others from learning anything about underlying patient records. However, there are only a few ways to achieve homomorphic encryption, and they are so computationally intensive that it is often infeasible to deploy them in the real world.

MIT researchers have developed a new theoretical approach to building homomorphic encryption schemes that is simple and relies on computationally lightweight cryptographic tools. Their technique combines two tools so they become more powerful than either would be on its own. The researchers leverage this to construct a “somewhat homomorphic” encryption scheme—that is, it enables users to perform a limited number of operations on encrypted data without decrypting it, as opposed to fully homomorphic encryption that can allow more complex computations.