Stream items read permission

Question

Hello

I created stream called "Patient_A_Record", I want to share the stream with my doctor. The solution that I read is to encrypt stream items before publishing it to Patient_A_Record Stream. But If I shared the key using symmteric key encryption, then the doctor will access my stream forever because I can't encrypt the data that is stored on blockchain again or change the key. Could you plz provide another solution or additional solution plz

thank you

Answer 1

Your best option would be not to embed the data in the blockchain at all, but only put (salted) hashes of the data on the chain to allow for timestamped verification. You would manage access to the data in an off-chain fashion. But even then you should note that, once a doctor's computer has seen some data, it can choose to store it forever, and another computer has no way of forcing it to delete that data. This is an issue with any kind of encryption scheme whether or not a blockchain is used together with it.