{"id":400,"date":"2018-10-31T09:27:41","date_gmt":"2018-10-31T09:27:41","guid":{"rendered":"http:\/\/nebulablog.wpengine.com\/?p=30"},"modified":"2020-12-28T19:04:46","modified_gmt":"2020-12-29T00:04:46","slug":"re-encryption-by-proxy-and-homomorphic-encryption","status":"publish","type":"post","link":"https:\/\/nebula.org\/blog\/re-encryption-by-proxy-and-homomorphic-encryption\/","title":{"rendered":"Re-encryption by Proxy and Homomorphic Encryption"},"content":{"rendered":"\n

Data use and data privacy are often in conflict. For example, if we all openly shared our health data with researchers, it would speed up work on new health technologies and cures. But we are rightly afraid of what a malicious actor could do with our raw health data. That is where the field of cryptography can come to the rescue. Re-encryption by proxy<\/em> and homomorphic encryption<\/em> are tools that will allow us to keep our cake and eat it too, when it comes to data use and data privacy.<\/p>\n\n\n\n

Re-encryption by proxy allows a data owner to encrypt their data once, and subsequently share it securely with buyers, as often as they wish, using the services of a third party. Homomorphic encryption allows a data buyer to run computations on encrypted data stored and computed on by untrusted third parties, and obtain results or insights on that data, while not revealing any individual\u2019s data in unencrypted form.<\/p>\n\n\n\n

These techniques serve as the building blocks of more complex crypto systems (for example Unlynx<\/a> developed by EPFL, the theoretical inspiration for our current work). Thus our plan is as follows 1) build out simple to use and practical libraries for advanced cryptography primitives 2) these libraries will help developers create and combine advanced primitives to create complex crypto systems that will allow more secure data sharing 3) More secure and useful data sharing will 10x the speed of research on important problems like cancer and diabetes research 4) save the world :-).<\/p>\n\n\n\n

To start off we\u2019ve developed an alpha version of a proof-of-concept library<\/a>. The code below uses that library to offer an example of how we apply those technologies to enable a secure and convenient data flow from owners to users.<\/p>\n\n\n\n

Re-encryption by Proxy<\/h3>\n\n\n\n

Re-encryption by proxy is a process in which a third party, called the proxy, alters a ciphertext encrypted by one party in such a way that it may be decrypted by a second party.<\/p>\n\n\n\n

On Nebula\u2019s platform, the proxy will act as a custodian for encrypted genomic data and manage access to that data by buyers on behalf of the owner. While the proxy cannot access the underlying raw data, the proxy is able (with the permission of the owner) to modify the encrypted data so that the user can subsequently decrypt it. The data owner is thus able to delegate this task to the proxy while never sharing any plaintext information with the proxy. Another consequence of this delegation is that neither the data owner nor recipient need to be online.<\/p>\n\n\n\n

In our example, assume the proxy is a set of servers that acts as a decentralized collective authority. Now, let\u2019s walk through an example of re-encryption by proxy where Alice, a data owner, shares genomic data with Bob, a data user, via the proxy.<\/p>\n\n\n\n

First let\u2019s install the library mentioned above.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Now we can import the nebula package.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n