<p>Nothing can prevent B from exposing or forwarding the data once he has access to it.</p>

CC BY-SA 3.0
2018-03-05T06:57:53.087Z
B only needs the data to run his evaluation logic, thus can B's logic be included in a smart contract where the read permission of the data can be given to the evaluation logic function? By this way, B can only see the output of the evaluation logic without getting exposure of the data. Is this possible?
Rajrup Ghosh
CC BY-SA 3.0
2018-03-05T09:47:58.803Z
@RajrupGhosh Okay, that sounds more doable but that is outside the scope of 'B is a pharmaceutical company who wants to view medical records from A'. In fact, A can run the logic for B as part of a smart contract where only the results are returned.
Willtech
CC BY-SA 3.0
2018-03-04T01:27:53.920Z
2018-03-04T01:27:53.920Z
Willtech
<p>Let's say A has some private medical records of patients and B is a pharmaceutical company who wants to view medical records from A to find out the effect of a particular drug on the patients (run a drug evaluation logic to get performance statistics of a particular drug). A wants to share the private data to B but wants to prevent B to forward (leak) the data to other third party organizations. How can this problem be solved with blockchain?</p>

CC BY-SA 3.0
2018-03-03T23:55:26.683Z
I would tend to say, that a blockchain is a record keeping system, and not a „forwarding prevention“ system. One B sees data in any blockchain, they can do screenshots and forward to other third party...
pebwindkraft
CC BY-SA 3.0
2018-03-04T21:06:00.203Z
B only needs the data to run his evaluation logic, thus can B's logic be included in a smart contract where the read permission of the data can be given to the evaluation logic function? By this way, B can only see the output of the evaluation logic without getting exposure of the data. Is this possible?
Rajrup Ghosh
CC BY-SA 3.0
2018-03-04T21:57:03.880Z
I think it is still not a blockchain specific topic. A blockchain holds publicly readable data. And you want to anonimize/hide it somehow, after it is published. I don't know how to do this. I'd be working at this when I input the data. E.g. when bringing the names on the blockchain, hash them, and the rest can just "go". The private key would then be required to show the real data. Maybe the idea of  multisig could be used? Or MimbleWimble/CoinJoin? (which are essentially smart contracts).
pebwindkraft
CC BY-SA 3.0
2018-03-05T06:56:10.240Z
Lets say its a permissioned blockchain like hyperledger where you can give permissions to who can view the data. One idea is given in page 4 of this paper https://enigma.co/ZNP15.pdf which deals with the same kind of problem, but I don't know how to implement the idea in smart contract.
Rajrup Ghosh
<blockchain><privacy><storage><private-blockchains>
Share private data and prevent data forwarding
Rajrup Ghosh
# Share private data and prevent data forwarding

(Asked by: username_0 on 2018-03-03)

Let's say A has some private medical records of patients and B is a pharmaceutical company who wants to view medical records from A to find out the effect of a particular drug on the patients (run a drug evaluation logic to get performance statistics of a particular drug). A wants to share the private data to B but wants to prevent B to forward (leak) the data to other third party organizations. How can this problem be solved with blockchain?

**Tags:** blockchain, privacy, storage, private-blockchains

> **Comments:**
> **username_1**: I would tend to say, that a blockchain is a record keeping system, and not a „forwarding prevention“ system. One B sees data in any blockchain, they can do screenshots and forward to other third party...  
> **username_0**: B only needs the data to run his evaluation logic, thus can B's logic be included in a smart contract where the read permission of the data can be given to the evaluation logic function? By this way, B can only see the output of the evaluation logic without getting exposure of the data. Is this possible?  
> **username_1**: I think it is still not a blockchain specific topic. A blockchain holds publicly readable data. And you want to anonimize/hide it somehow, after it is published. I don't know how to do this. I'd be working at this when I input the data. E.g. when bringing the names on the blockchain, hash them, and the rest can just "go". The private key would then be required to show the real data. Maybe the idea of  multisig could be used? Or MimbleWimble/CoinJoin? (which are essentially smart contracts).  
> **username_0**: Lets say its a permissioned blockchain like hyperledger where you can give permissions to who can view the data. One idea is given in page 4 of this paper https://enigma.co/ZNP15.pdf which deals with the same kind of problem, but I don't know how to implement the idea in smart contract.  

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## 1 answers

### Answer by username_2 on 2018-03-04. Score: 1

Nothing can prevent B from exposing or forwarding the data once he has access to it.

> **Comments:**
> **username_0**: B only needs the data to run his evaluation logic, thus can B's logic be included in a smart contract where the read permission of the data can be given to the evaluation logic function? By this way, B can only see the output of the evaluation logic without getting exposure of the data. Is this possible?  
> **username_2**: @username_0 Okay, that sounds more doable but that is outside the scope of 'B is a pharmaceutical company who wants to view medical records from A'. In fact, A can run the logic for B as part of a smart contract where only the results are returned.  

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