Consider as an example the following setting.

A set of universities want to keep track of the joint list of students. Ideally, each university will have a "consistent" copy of this list, and whenever some student joins/leaves any of the universities, all the lists get updated accordingly.

Alternatively, we may consider an email service provider that has multiple servers and they want to make sure all servers have the same view of each email account in the service, or an airline wants to make sure all of its servers know in a consistent manner how many tickets they have available. These problems are old, and have had solutions for while.

From my point of view, Blockchain achieved something crucial from a technical (perhaps social?) point of view: consensus in a permissionless setting withstanding byzantine participants. However, there is a huge and old body of research studying more permissioned settings like the ones above, and there are tons of techniques there (PAXOS and derivatives).

My concrete question is: If I have some of the more traditional settings highlighted above, do I benefit in any way from using a Blockchain? (e.g. are they more efficient under some metric? do they scale better to a large number of nodes? are they simpler and easier to implement?). What if the setting is permissioned but we want to withstand byzantine adversaries?

As an interesting note, there might be at least one benefit: you may be able to leverage existing implementations, among which there could be more in the Blockchain domain? But I'm looking for more meaningful benefits.

  • $\begingroup$ No, no, no, no, no, and no. If you need to keep track of ownership/transactions in a decentralised way, then perhaps. But if you are a centralised authority, then use a database. $\endgroup$
    – Pål GD
    Oct 14, 2021 at 21:58
  • $\begingroup$ Whether or not blockchain has any "meaningful benefit" is an open question, and not really one that computer science can answer. $\endgroup$
    – Pseudonym
    Oct 14, 2021 at 23:07
  • $\begingroup$ @Pseudonym Interesting view. Why do you think it goes outside computer science? I was asking something objective within the field: whether Blockchains achieved something in terms of other "database consensus" protocols, like, better communication complexity? Better resilience to crashes/faults/byzantine? More scalability? I honestly do not think any of these hold, but then, I would appreciate some pointers to "classical" techniques that work better than blockchains in permissioned settings. $\endgroup$
    – Daniel
    Oct 15, 2021 at 0:59
  • $\begingroup$ @Daniel I was perhaps caught by the word "meaningful". $\endgroup$
    – Pseudonym
    Oct 15, 2021 at 1:50
  • $\begingroup$ @PålGD That's also my belief, but I would like to count on some specific pointers and references that support this claim. For example, what are the state of the art protocols to achieve the same functionality as Blockchain (a totally-ordered broadcast "book"), that do not use the Blockchain? Do they scale well for a large number of nodes? What is their communication complexity when compared to Blockchain approaches? $\endgroup$
    – Daniel
    Oct 15, 2021 at 2:30


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