Can consensus take place between only 2 peers?

Scenario: I am a patient who is visiting a doctor and all the communication/transaction between the both of us happen via a blockchain based app. So the transaction at that time would mainly be about my diagnosis, medicines prescribed and so on. And before this data gets committed on the ledger it needs to get validated via a consensus algorithm. So how would consensus take place in such a scenario.

All the suggestions/helps/comments are appreciated and welcome. Thanks!

2 Answers 2


The consensus algorithm employed in ethereum is an automatic one. it serves as a way of agreement between the nodes in the blockchain network. It doesn't have any collision what so ever with any application that is built on top of the ethereum network.

So the consensus algorithm in your case will be executed as it is done for any kind of other application.

TLDR : The application type and/or goal doesn't matter to the consensus algorithm.

  • thanks @kaki, but can you please help me in understanding how consensus happens in a private network? There are no miners, hence there is no incentivisation process. Then who adds the blocks to the ledger and how? Sep 27, 2018 at 6:53
  • The concsensus algorithm takes care of the process of adding blocks. You need to implement or use the available consensus algorithm in a private network. For the case of ethereum you can try the testNet Ropsten ( it uses proof-of-authority ) or the main net (uses proof-of-work, which introduces the mining and miners). Sep 27, 2018 at 9:07
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    Ok @kaki, thanks a lot man. let me check out these 2 and I will get back to you in case I need further clarification. cheers! Sep 27, 2018 at 10:32

If you trust each other, you don´t need blockchain. You trust your doctor, right? And your doctor trust you. Use a simple relational database.

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