Is blockchain always "public"?

Is the following definition of blockchain by its wikipwdia page correct?

Where it is mentioned:

A blockchain is a decentralized, distributed and public digital ledger ...

Cannot we have a private blockchain? And if so, is the above proposition wrong ? when it says always a blockchain is public.

An example: Consider a company or organization which aims at using (permissioned) blockchain such that it is visible only for its (internal) employees. So, it uses ex. visibility property of blockchain but limited only to internal employees.

Please Note that here the question is NOT if using a permissioned blockchain is logical or not, but also the question is the exact definition of a blockchain. So, according to definition of blockchain in its wikipedia page, a permissioned blockchain is real blockchain?

Questioner

Posted 2018-08-26T13:40:36.733

Reputation: 906

Answers

Ok, you can create your own private blockchain. It will be visible only by yourself. Nobody will not even know about it. I do not see any reason for it, but you can call it "blockchain" if you want. You can call it "my private blockchain" or even give any name for this technology, for example "nsdfuishgreryuiw"

amaclin

Posted 2018-08-26T13:40:36.733

Reputation: 5 763

Consider a company or organization which aims at using (permissioned) blockchain such that it is visible only for its (internal) employees. So, it uses ex. visibility of blockchain but limited only to internal employees. – Questioner – 2018-08-26T14:52:38.407

Their are two kinds in blockchain

Permission less
Permission-ed

In Permission less blockchain (Bitcoin) it's public. And anyone can join network. In Permission-ed blockchain (Private company) ,participants are known and it may not be public to everyone.

VforVendetta

Posted 2018-08-26T13:40:36.733

Reputation: 102

In regards to bitcoin, yes, the blockchain is always public. The reason behind it is that it needs to be. Without having public access to the bitcoin blockchain the whole system would not work. A miner for example could not verify pending transactions because how would he know if they are valid or not without checking the blockchain? The public blockchain is a part of what makes bitcoin so special - without it, bitcoin would not be a decentralized network. You would need a central authority which manages the blockchain and keeps it private, just like a ... bank.

So in conclusion, the blockchain need to be accesible to everybody who wants to take part. As bitcoin wants everybody to be able to take part, everybody needs access to the blockchain.

thesys

Posted 2018-08-26T13:40:36.733

Reputation: 179

Thank you, but my question is, in general, blockchain and not necessarily Bitcoin blockchain. – Questioner – 2018-08-26T15:50:55.623

If you could extend your question and describe what you are actually trying to achieve we might be able to help you more. – thesys – 2018-08-26T15:53:05.417

I edited my question. My main question is about correctness of proportion of blockchain wikipedia page (i.e. blockchain is alway a public ledger?) and permissioned blockchain. – Questioner – 2018-08-26T16:00:27.883

Well of course you could deploy some kind of "private blockchain technology" inside a company. But why not simply use the existing and working system? – thesys – 2018-08-26T16:04:26.463

It's not my purpose, but also I want to be sure that if the existing definition of blockchain in its wikipedia page is correct? Is a permissioned blockchain public ? The fact that deploying a private blockchain is logical or not is another question. The question is definition of a blockchain. – Questioner – 2018-08-26T16:27:35.440

By the pure technical definition: no, a blockchain does not need to be public. It must however be accesible to everybody who wants to take part in the system. The reason why the wikipedia page says it is public is because there they are talking about real world applications like bitcoin. – thesys – 2018-08-26T16:36:06.133

OK, but the page is not about only Bitcoin BC, but also it defines generally the BC. From my point of view, to have an immutable BC, we need the blockchain to be maintained by a decentralized consensus, otherwise in case of using ex. PoA and permissioned approach, since it's a centralized approach, there is no guarantee for a BC user that in future what happens for the BC and if the BC will exist after years? So, in this case, there is no guarantee for existing transactions history in future. And at this point question is why do we use such a blockchain? – Questioner – 2018-08-26T16:45:42.230

blockchain is not immutable – amaclin – 2018-08-26T18:32:30.380

@amaclin It depends on which consensus mechanism we use. ex. in case of using PoA, if pre-selected validators decide to change/remove the whole of blockchain, it's possible. When we talk abut blockchain, we don't talk necessarily talk about Bitcoin blockchain. Meanwhile, do you mean action history? and if so, blockchain is not reliable anymore. – Questioner – 2018-08-26T19:15:38.553