The following scenario can be suggested as the simplest option:
- We create a smart contract with 3 methods:
- RegistryRequest(bytes32 info_id, bytes32 user_id, string memory public_cert) payeble
- SendInfo(bytes32 info_id, bytes32 user_id, string file_addr)
- GetInfo(bytes32 info_id, bytes32 user_id) view return(string memory retVal)
- The consumer calls the method RegistryRequest transfers:
- info_id - the identifier of the required data
- user_id - his unique identifier (e-mail, mobile phone, and so on) ()
- public_cert- his public key OpenSSL and attaches a certain amount in Eth to the transaction as payment for the service.
- Having received the details and payment from the consumer, you:
- create a file with the data he needs
- encrypt this file with the consumer's public key OpenSSL,
- upload it to some web resource or transfer it via IPFS or Ethereum Swarm (or in any other way)
- using the method SendInfo lay out the "address" of the data file (file_addr) in relation to the data and consumer identifiers (info_id, user_id). To pay for the transaction, you use a portion of the amount received from the consumer along with the RegistryRequest.
The consumer through the method GetInfo using the data identifier (info_id) and his personal identifier (user_id) receives the "address" of the data file, extracts and decrypts it
If the data changes, then their changed state is laid out similarly to point 3
After the expiration of the data provision period, you stop releasing their update
More complex solutions can, for example, be discussed with experts for free and simulated on a kekker.com
That a nice answer thank you, showing that the diploma example is not a good one. So how about changing diploma with medical records and employer with insurance company?
Do I understand correctly that you want to provide the user with the opportunity for a limited time to observe all changes to the record? Or do you want to give him a one-time current state of data?
I would like to give him the opportunity to observe the changes to the record from state x to state y.
See solution in the answer
That exactly the kind of answer I was looking for. Thank you very much.