Blockchain : Why is blockchain more secure w.r.t. accessing data?
I have a general question on the blockchain technology. In an article about how medical patient data can be stored on a blockchain, the author explains why decentralized systems are more secure than centralized systems. He says that in a centralized system a large amount of data is stored on a small number of servers and a hacker gets access to lots of sensitive data when he succeeds in hacking one of these systems.
So far I agree.
Then the author explains why a decentralized system is more secure. He says that in a blockchain there is no central server that can hacked. Data is stored by everybody in a decentralized ways. To access this data, each pair of private-public keys of all user had to be hacked. Therefore, if the hacker wants to access e.g. sensitive data of 1000 users he needs to hack 1000 keys which is an enomous effort.
I don’t understand this argumentation. My questions here are:
1) What information would be stored for such a “medical” blockchain application on the blockchain? Would all the medical data (reports, diagnoses …) be stored as “plain text” or would they be encrypted by the user’s private key so that only the user by himself could access the data (i.e. no doctor could have access to this data, it’s only the patient that has his private key and can grant access to other users)?
2) I also don’t really understand the statement that data is stored by evey user in a decentralized way. To my understanding, each node of a blockchain holds all data for all patients. So if any node is hacked, the attacker gets access to all data. So where is the benefit compared to a centralized system?
Happy to hear your answers to my two questions.
What is the Blockchain?
A block chain is a transaction database shared by all nodes participating in a system based on the Bitcoin protocol. A full copy of a currency’s block chain contains every transaction ever executed in the currency. With this information, one can find out how much value belonged to each address at any point in history.
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