Ensuring data privacy in a blockchain using PRE

Before getting any further and building our decentralized EMR data management and sharing system, let's learn about what PRE is. In our solution, we will be using PRE to ensure security and privacy. 

PRE is a set of algorithms that allows you to encrypt some text with your key and then alter the ciphertext so that it can be decrypted by another party without revealing your key. To alter the ciphertext, you need the other party's private or public key, based on whether you are using interactive or noninteractive PRE algorithms, respectively. Regardless of the algorithm, PRE involves generating a re-encrypt key, which is used to re-encrypt the data. The re-encrypt key is generated based on the owner's private key and the recipient's private or public key, based on the type of algorithm.

In practice, PRE is used to store sensitive data on a third-party server and lets you decide who gets access to the data without revealing the actual data to the...