For a business use case I am conceptualizing for my master's thesis, wich is based on a Blockchain system, I need to understand impacts on decentralization/trustlessness.

Many people argue that private instances are utter nonsense, and you might as well use centralized databases because you need some kind of access control to let parties join the network and therefore and central entity controls it all. In my case, a consortium of three companies would set up a private Blockchain for confidentiality reasons.

Question: How to implement access to permissioned/private/consortium Blockchains in a decentralized or at least democratic manner?

If the nodes and their respective network addresses are defined contractually, let's say each stakeholder sets up 3 nodes, I don't see the need need for a central gate keeper. A befriended ethcore dev told me that still anybody could join the network an compromise it, yet I don't know how and why. Alternatively, I could imagine staking as Sybil-control where each member gets an equal share.


You could create a smart contract token, even on a public block chain, requiring a user to have one of a predetermined set of wallet addresses.

Alternatively, you could use a system like Blockstack in a similar way to SSO. Where you limit users logging in to a specific set of domains @whitelist.com, @partners.com, etc

  • I am aware the access control mechanisms allowing only transactions from certain pubkeys and I also consider this type of implementation but it does not solve privacy associated issues. zk-SNARK transactions cost up to 1.6 million gas which is not feasible. – Marcellvs Dec 10 '18 at 12:58
  • You could use the same mechanism with a private blockchain – Vinnie James Dec 10 '18 at 12:59
  • You are right, and in order to keep in decentralized on consortium level I would require a multi-sig mechanism in order to add or remove certain participants? – Marcellvs Dec 10 '18 at 13:19
  • Yes, that's one of many ways – Vinnie James Dec 10 '18 at 13:29
  • @marcellvs how does zk SNARK cost that much gas? Curious to know. – cogitoergosum Mar 6 '19 at 16:28

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