My student Dragan Rakas and I worked on an early version of this technology in 2013, and we found it to be a very interesting but difficult problem. You can read our about it here.
Microsoft has open sourced a homomorphic encryption library developed by its Cryptography Research group, saying it “strongly believes” the technology is ripe for use in real-world applications, as it makes the source code available on GitHub. (Here is the link to the GitHub repository.)
Source: Microsoft Open Sources Homomorphic Encryption Library