First of all, I am completely new to blockchains so sorry if I'm asking any silly questions:)

I would like to build a test web project: users can create accounts and manage various kinds of agreements e.g. one user borrow some money to another one, the first one creates an agreement and the second one should sign it.

I would like to use private Ethereum chain as a database to ensure all the agreements are immutable so that anyone could prove it validity. For now I'm thinking of having several nodes with the chain with PoA, several nodes with servers handling e.g. authorization and frontend.


  • Is it a valid use case or should I simply use a database?
  • Will I get some additional security bonuses if I use the chain?
  • Should I store agreements itself in a chain?
  • Should create user accounts straight in a chain thus not having to use any backend I mean using contracts only?

Thank you very much!

  • It's Ethereum, with a "e", not a "i". Commented Mar 16, 2018 at 18:38
  • I was just kidding you ;) Commented Mar 16, 2018 at 18:43
  • 1
    @Nicolas Massart ahah, at first I was like "?!" but I could do such a stupid mistake) Commented Mar 16, 2018 at 18:48

1 Answer 1


I think there is an inherent conflict between the assumption of a private blockchain and the idea the data in this chain would be immutable.

The argument that things in the public blockchain are essentially immutable has merit, because you would have to get the entire blockchain to conspire to edit the blockchain to make a change. OTOH, a private blockchain is under the control of one entity. How do you ensure that it won't backtrack and write new blocks?

So at the very least, I would recommend a hybrid approach in which the hashes in your private chain are pushed someplace public and immutable to lock them in and truly ensure immutability. Not necessarily every transaction (defeats the purpose), but at key points.

  • thanks for the answer! however, it is not clear for me why then I use private blockchain at all, what are use cases? how should I use my blockchain? Commented Mar 16, 2018 at 18:35
  • I view the private blockchain as being essential for testing, and then useful only for certain specific applications. If you want to use it for immutability for internal purposes, and essentially "trust yourself" not to muck with it, you don't need the hybrid approach. If you need to prove your immutability to others, you can export hashes to the "real" blockchain to have that effect. I think blockchain.ieee.org/clinicaltrialsforum-2018 gives some good examples. Commented Mar 19, 2018 at 13:40

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