Public blockchains are just that, public. Anyone that wants to read, write, or join a public blockchain can do so. Public chains are decentralized meaning no one body has control over the network, ensuring the data can’t be changed once validated on the blockchain. Simply meaning, anyone, anywhere, can use a public blockchain to input transactions and data as long as they are connected to the network.
When blockchain technology was introduced to the public in 2008 (via Satoshi Nakamoto’s famous white paper), it would have been hard to predict that private or consortium blockchains would become popular. But recently, there’s been a lot of buzz about this in the digital currency community. Many companies are beginning to experiment with blockchain by implementing private and consortium chains, although some people are critical of this. This discussion not only centers on use cases and benefits, but whether non-public blockchains are an appropriate application of the protocol to begin with.
The top 10 Ethereum decentralized apps (DApps) have daily active user counts in the thousands. Compare this with a centralized platform like Facebook, which has over a billion daily users, and you can see just how small scale blockchain use still remains. For a detailed comparison, read “State of the DApps: 5 Observations From Usage Data (April 2018)”.
A typical use case for a private blockchain is intra-business: when a company decides to implement blockchain as a business solution, they may opt for a chain to which only company members have access. This is useful if there’s no need for anybody outside of the company to become part of the chain, because private blockchains are more efficient than public and consortium chains. Also, because they are smaller and contained, it is easier for a consensus process or other technical stipulation to be altered on a blockchain. So, for example, if the developers or proprietors want to change the cryptographic method which runs its consensus process, it is much easier to do this on a private blockchain than a public or consortium chain.

@mowliv I think a good way to think about it is by looking at our economy. The Federal Reserve prints US dollars for the US Government (the main blockchain) to boost the US economy. However, US dollars can be exported to other countries (a side chain) that could have a completely independent economy but still use a currency backed by the US government. – Olshansk May 30 '17 at 0:56
Another promise of sidechains is the ability to have a stronger and faster mainchain, as transactions can happen on one of the sidechains. If users or developers are dissatisfied with the costs of sending a transaction and the transaction speed of the mainchain, they can use and or deploy their dapp on one of the sidechains. This leads to a more diversified network and a stronger, faster and more robust mainchain.
Public blockchains are just that, public. Anyone that wants to read, write, or join a public blockchain can do so. Public chains are decentralized meaning no one body has control over the network, ensuring the data can’t be changed once validated on the blockchain. Simply meaning, anyone, anywhere, can use a public blockchain to input transactions and data as long as they are connected to the network.
• ‘Difficulty’: In the Bitcoin network, miners solve an asymmetric cryptographic puzzle to mine new blocks. Over time the puzzle becomes easier, resulting in it eventually taking less than 10 minutes for each new block generation. Hence, the community updates the puzzle every 14 days and makes it more difficult, thus requiring even more computing power to handle the POW algorithm. The ‘difficulty’ parameter controls the complexity of the cryptographic puzzle. This parameter is also used in the Ethereum blockchain as well. Developers should assign a low value (between 0-10,000) to this parameter for this project thus enabling quicker mining.
The top 10 Ethereum decentralized apps (DApps) have daily active user counts in the thousands. Compare this with a centralized platform like Facebook, which has over a billion daily users, and you can see just how small scale blockchain use still remains. For a detailed comparison, read “State of the DApps: 5 Observations From Usage Data (April 2018)”.
State of the art public Blockchain protocols based on Proof of Work (PoW) consensus algorithms are open source and not permissioned. Anyone can participate, without permission. (1) Anyone can download the code and start running a public node on their local device, validating transactions in the network, thus participating in the consensus process – the process for determining what blocks get added to the chain and what the current state is. (2) Anyone in the world can send transactions through the network and expect to see them included in the blockchain if they are valid. (3) Anyone can read transaction on the public block explorer. Transactions are transparent, but anonymous/pseudonumous.
This is justified by observing that, in our pre-sidechain world, miners always want things to be correct. In theory, the incentives of miners and investors are very strongly aligned: both are compensated most when the exchange rate is highest. And, in practice, we do not see large reorganizations (where miners can “steal”, by first depositing BTC to major exchanges, then selling that BTC for fiat (which they withdraw), and finally rewriting the last 3 or 4 days of chain history, to un-confirm the original deposits). These reorgs would devastate the exchange rate, as they would cast doubt on the entire Bitcoin experiment. The thesis of Drivechain is that sidechain-theft would also devastate the exchange rate, as it would cast doubt on the entire sidechain experiment (which would itself cast doubt on the Bitcoin experiment, given the anti-competitive power of sidechains).

Step back from the details for moment and consider what’s been described.  We now have a way to move coins from Bitcoin onto another platform (a sidechain) and move them back again.   That’s pretty much what we do when we move them to a wallet platform or an exchange.  The difference is that the “platform” they’ve been moved to is also a blockchain… so it has the possibility of decentralised security, visibility and to gain from other innovation in this space.


Another promise of sidechains is the ability to have a stronger and faster mainchain, as transactions can happen on one of the sidechains. If users or developers are dissatisfied with the costs of sending a transaction and the transaction speed of the mainchain, they can use and or deploy their dapp on one of the sidechains. This leads to a more diversified network and a stronger, faster and more robust mainchain.
The witnesses who put more funds in escrow have a greater chance of mining (or minting) the next block. The incentives line up nicely here. There are only a few witnesses and they get paid to be witnesses, so they are incentivized to not cheat. If they do cheat and get caught, they not only get voted out in favor of the next eagerly awaiting witness, they lose all the funds they had in escrow.
Hasta la fecha (Agosto del 2016), las sidechains sobre Bitcoin no son más que algo teórico. Una implementación de este tipo requeriría de un cambio en el código Bitcoin (hay miembros de la comunidad Bitcoin con gran prestigio, como es el caso de Peter Todd, que argumentan que una sidechain, tal y como la describe Blockstream en su paper, no podrían llevarse a la práctica en Bitcoin sin hacer un gran cambio, hard fork, en Bitcoin). En el mismo paper de blockstream se reconoce que una implementación de este tipo, la cual su teoría es simple pero su implementación compleja, se enfrenta a problemas que no está del todo claro que puedan solventarse (y no todos son de tipo técnico).
Frankly, secure implementation of Bitcoin is already a pain in the ass .. adding more complexity just seems like the wrong move at this point. It’s already trying to be a currency, a networking protocol and a client in the same codebase. Adding turing complete (or not) scripts with arbitrary outcomes, multiple versions of the official client cooperating, multiple clients, and now multiple blockchains is basically the nail in the coffin in terms of widespread implementation.
Ardor is a blockchain platform predicated on childchains (sidechains) that use proof of stake (PoS) consensus. It uses the primary chain as a security chain and the childchains for processing transactions to increase scalability. Their design is specifically focused on speed and efficiency through PoS consensus and removing blockchain bloat through pruning.
Blockchain, trust, decentralization, Bitcoin, transparency, anonymity, blockchain, blockchain, blockchain. These words seem to appear randomly on the Web regardless the theme of an article you read. Don’t you know how to implement blockchain in art? There’s definitely someone who can tell you. Do you wonder how banking can benefit from blockchain? No worries, some projects already do it – just search for the use cases.
At Iryo, we consider databases and blockchains that are not opened to the public to be insecure they, can easily be altered by the business running it, at their discretion and it goes against the ethos of the open and transparent cryptocurrency space. Designed to keep public out and introducing “trusted” middlemen, private chains forget that trusted third parties are security holes.
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In general, so far there has been little emphasis on the distinction between consortium blockchains and fully private blockchains, although it is important: the former provides a hybrid between the “low-trust” provided by public blockchains and the “single highly-trusted entity” model of private blockchains, whereas the latter can be more accurately described as a traditional centralized system with a degree of cryptographic auditability attached. However, to some degree there is good reason for the focus on consortium over private: the fundamental value of blockchains in a fully private context, aside from the replicated state machine functionality, is cryptographic authentication, and there is no reason to believe that the optimal format of such authentication provision should consist of a series of hash-linked data packets containing Merkle tree roots; generalized zero knowledge proof technology provides a much broader array of exciting possibilities about the kinds of cryptographic assurances that applications can provide their users. In general, I would even argue that generalized zero-knowledge-proofs are, in the corporate financial world, greatly underhyped compared to private blockchains.
It is different with a private blockchain (or closed) since the members of the network are selected before being able to download the protocol and therefore use the proposed service by the network. The mining capabilities and the system of consensus as a whole are centralized within the hands of the same entity. A network based on a private blockchain is therefore not decentralized in itself.
Blockstream believes that to be secure, blockchain systems must be built with open source technology. Towards that goal, we've created the Elements Project, a community of people extending and improving the Bitcoin codebase. As open source, protocol-level technology, developers can use Elements to extend the functionality of Bitcoin and explore new applications of the blockchain. Join the expanding group of individual and corporate developers using Elements to build robust, advanced, and innovative blockchains.
A federation is a group of servers that act as an in-between point between the main chain and a sidechain. The Federation decides when the user’s coins are locked as well as when they are released. The developers of the sidechains can choose the members of the federation. The downside to using federations is that they add another layer between the sidechains and the parent chain.
A big thanks to Diego Salvador for helping me write this episode. Him and the rest of the team over at Rootstock are doing fantastic work with cryptocurrency and Sidechains. We wish them all the best. I'll be sure to leave a link to their website in the top of the description so you can go check it out and learn more if you wish. And as always, be sure to subscribe and I will see you next time.

Given all of this, it may seem like private blockchains are unquestionably a better choice for institutions. However, even in an institutional context, public blockchains still have a lot of value, and in fact this value lies to a substantial degree in the philosophical virtues that advocates of public blockchains have been promoting all along, among the chief of which are freedom, neutrality and openness. The advantages of public blockchains generally fall into two major categories:
• ‘Difficulty’: In the Bitcoin network, miners solve an asymmetric cryptographic puzzle to mine new blocks. Over time the puzzle becomes easier, resulting in it eventually taking less than 10 minutes for each new block generation. Hence, the community updates the puzzle every 14 days and makes it more difficult, thus requiring even more computing power to handle the POW algorithm. The ‘difficulty’ parameter controls the complexity of the cryptographic puzzle. This parameter is also used in the Ethereum blockchain as well. Developers should assign a low value (between 0-10,000) to this parameter for this project thus enabling quicker mining.
It’s the IBM “blockchain”. Basically Apache Kafka queue service, where they have modified the partitions. Each partition is an ordered, immutable sequence of messages which are continuously appended. They added some “nodes” to clean the inputs and voila; blockchain! We should add that there are no blocks, but batches of transactions are renamed to fit the hype better. Since everything gets written in one queue at the end of the day, IBM offers the bluemix cloud server (priced at 120.000$ per year) to host the service. Smaller test packages with a couple of input cleaning nodes go reportedly for 30.000$.
A consortium blockchain is part public, part private. This split works at the level of the consensus process: on a consortium chain, a pre-selected group of nodes control the consensus process, but other nodes may be allowed to participate in creating new transactions and/or reviewing it. The specific configuration of each consortium chain (i.e., which nodes have the power to authorize transactions via the consensus process, which can review the history of the chain, which can create new transactions, and more) is the decision of each individual consortium.
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