So if you want to create a more secure Sidechain, we would seriously need to have a look at incentivizing miners in other ways. These could include things such as the Sidechain raising outside funding from investors in order to pay the miners. Staggering mining award so miners have an incentive to keep mining as they will be paid later on rather than at the time or the Sidechain could issue its own mining award on top of the already existing transaction fees and essentially just become an Altcoin.
@gendal, good question. Think of the identity hash as a bitcoin address, it is indeed public. So to assert anything with this identity you need to sign the object you are creating or changing with the identity’s private key. Specifically it is a private key that corresponds to a public key that you published in your identity’s object (json). The signature is not placed on the bitcoin transaction, as OP_RETURN has only 40 bytes. The signature is added to a [json] object that is modified with this identity. If you see any fault with this, please let me know.
A public blockchain is a platform where anyone on the platform would be able to read or write to the platform, provided they are able to show the proof of work for the same. There has been a lot of activity in this space as the number of potential users that any technology in this space could generate is high.  Also, a public blockchain is considered to be a fully decentralized blockchain. Some of the examples are:
A blockchain is a decentralized, distributed and public digital ledger that is used to record transactions across many computers so that the record cannot be altered retroactively without the alteration of all subsequent blocks and the consensus of the network.[1][18] This allows the participants to verify and audit transactions inexpensively.[19] A blockchain database is managed autonomously using a peer-to-peer network and a distributed timestamping server. They are authenticated by mass collaboration powered by collective self-interests.[20] The result is a robust workflow where participants' uncertainty regarding data security is marginal. The use of a blockchain removes the characteristic of infinite reproducibility from a digital asset. It confirms that each unit of value was transferred only once, solving the long-standing problem of double spending. Blockchains have been described as a value-exchange protocol.[13] This blockchain-based exchange of value can be completed quicker, safer and cheaper than with traditional systems.[21] A blockchain can assign title rights because, when properly set up to detail the exchange agreement, it provides a record that compels offer and acceptance.
In this article, I will intent to do a public vs private (permissioned) blockchain comparison. This will include an examination of what exactly the roles of these two types of blockchain really are and why big businesses should quickly move to adopt them. This analysis will look at why private blockchains are better suited to big business use when compared to public ones.
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.
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.
Bitcoin and Ethereum blockchains use the ‘proof of work’ (POW) consensus algorithm to provide maximum security. It relies on a process called ‘mining’, which involves nodes trying to find the cryptographic hash of the last recorded block in order to create a new block. This is a massive number-crunching operation. It’s computing-power and energy-intensive, and becomes increasingly costly as the blockchain length grows. Read more about POW in this article “Proof of work vs proof of stake comparison”. This makes such blockchains impractical in a large business context.
New organizational structures will emerge that will make inside/outside much less clear. These clear boundaries started to erode with the extranets in the 90s, then with the multi-tenant cloud platforms, and lately with the smartphones and the IoT. As we move forward we will see value chains where participants have multiple roles and affiliations. We will be designing token based systems that produce gains for any participants, internal or external.
In this article, I will intent to do a public vs private (permissioned) blockchain comparison. This will include an examination of what exactly the roles of these two types of blockchain really are and why big businesses should quickly move to adopt them. This analysis will look at why private blockchains are better suited to big business use when compared to public ones.
As we’ve talked about, writing to the blockchain is slow and expensive. This is because every node in the entire network needs to verify and slurp in the whole blockchain and all the data it contains. Executing a large smart contract on a blockchain can be prohibitively expensive, and doing things like storing images on blockchains is economically infeasible.

Of course, the drawbacks of public and private blockchains are still very much present in the case consortium chains. This all depends on the way each consortium is constructed: a more public consortium chain will bear the burdens of public chains, while a more private one might suffer from the relative lack of openness and disintermediation. The right configuration depends on the needs and vision for each specific chain. Strategy and tailoring are always necessary to get the best solution.
In order to trade assets from the mainchain for assets from the sidechain, one would first need to send their assets on the mainchain to a certain address, effectively locking the assets up. After the transaction has been completed, a confirmation will be communicated to the sidechain. The sidechain will then release a certain amount of the assets on the sidechain to the user, equivalent to the amount of assets ‘locked up’ on the mainchain times the exchange rate. To trade the assets from the sidechain for assets of the mainchain, one would need to do the same, just the other way around.
“The only reason the banks have gotten to the point of thinking about permissioned ledger is because they finally reached the stage of bargaining, third stage in five stages of grief, for industry they’re about to lose. They start with denial, and the basis of denial is, well, this thing isn’t gonna work, it’s gonna die any day soon, and it doesn’t. And then they say, it’s just silly money and it doesn’t have any value, until it does; and no one else is gonna play with it, except they are; serious investors won’t put money into this, except they did; and it still refuses to die. We go from denial to bargaining. Somewhere in between might be anger, some depression, and eventually they’re going to reach acceptance, but it’s gonna take a long time. 
Public chains to the rescue! Public chains offer public transaction data that can be verified in real-time by anybody that cares to run a node. The more independent users or institutions that take part in verification, the more secure and decentralised the chain becomes! At Iryo, we strive to have every clinic doing full validation of the global state for the relevant smart contracts (EOS based). Public blockchains are mainly useful for two things; value routing (including initial creation and distribution) and trustless timestamping of messages.
Pegged sidechains employ a two-way peg to transfer assets between chains, and they consist of providing proof of possession in the transferring transactions. The idea is to enable the capability of locking an asset on an original parent chain, which can then be transferred to a sidechain before eventually being redeemed on the original chain. Notably, the original asset on the parent chain is locked in a specific output address and is not destroyed like early implementations of sidechains.
A blockchain is a decentralized, distributed and public digital ledger that is used to record transactions across many computers so that the record cannot be altered retroactively without the alteration of all subsequent blocks and the consensus of the network.[1][18] This allows the participants to verify and audit transactions inexpensively.[19] A blockchain database is managed autonomously using a peer-to-peer network and a distributed timestamping server. They are authenticated by mass collaboration powered by collective self-interests.[20] The result is a robust workflow where participants' uncertainty regarding data security is marginal. The use of a blockchain removes the characteristic of infinite reproducibility from a digital asset. It confirms that each unit of value was transferred only once, solving the long-standing problem of double spending. Blockchains have been described as a value-exchange protocol.[13] This blockchain-based exchange of value can be completed quicker, safer and cheaper than with traditional systems.[21] A blockchain can assign title rights because, when properly set up to detail the exchange agreement, it provides a record that compels offer and acceptance.
Open blockchains are more user-friendly than some traditional ownership records, which, while open to the public, still require physical access to view. Because all early blockchains were permissionless, controversy has arisen over the blockchain definition. An issue in this ongoing debate is whether a private system with verifiers tasked and authorized (permissioned) by a central authority should be considered a blockchain.[36][37][38][39][40] Proponents of permissioned or private chains argue that the term "blockchain" may be applied to any data structure that batches data into time-stamped blocks. These blockchains serve as a distributed version of multiversion concurrency control (MVCC) in databases.[41] Just as MVCC prevents two transactions from concurrently modifying a single object in a database, blockchains prevent two transactions from spending the same single output in a blockchain.[42]:30–31 Opponents say that permissioned systems resemble traditional corporate databases, not supporting decentralized data verification, and that such systems are not hardened against operator tampering and revision.[36][38] Nikolai Hampton of Computerworld said that "many in-house blockchain solutions will be nothing more than cumbersome databases," and "without a clear security model, proprietary blockchains should be eyed with suspicion."[9][43]
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.
Sidechains offer a way for new, more radical settings and technologies to be implemented without affecting the main chain. This ensures that the main chain is as secure as possible whilst providing the freedom to explore options which would never be considered for use on the main chain. Sidechains should be quite powerful as they provide cases like anonymity, transparency, confirmation times and turing complete options like rootstock all whilst utilizing bitcoins rather than relying on the hashing power (security) of some far less secure alt coin. That being said… there is quite some controvery regarding blockstream’s funding of most of the core development team and their inflexiblity regarding the max blocksize. This inflexibility has directly contributed to the success of ethereum and it remains to be seen whether the dream of bitcoin maximalism will survive long enough for sidechains with all of the promised functionality to be rolled out. I am skeptical.
We use node 2 to receive a payment of 200 via the smart contract function, receivePayment(). Note that the receivePayment() function can accept a second parameter for the account address that is used to create this transaction. (Note that you can also set web3.eth.defaultAccount = "<…account address…>", after which you can just call receivePayment(200) with one parameter.)
Private institutions like banks realized that they could use the core idea of blockchain as a distributed ledger technology (DLT), and create a permissioned blockchain (private or federated), where the validator is a member of a consortium or separate legal entities of the same organization. The term blockchain in the context of permissioned private ledger is highly controversial and disputed. This is why the term distributed ledger technologies emerged as a more general term.
Function Transactions executed between the locks and unlocks of the main chain tokens don't bloat the main chain. As the technology of a side chain is connected to its main chain, it can be used to build on the developments of the main chain and introduce new features to the market. Child chains serve as the transactional chains of the parent-child architecture, as the parent chain retains minimal features.
If you want a deeper look at Proof of Stake check out our detailed POS post. In short, while Proof of Work is an effective mechanism to secure the blockchain and provides a trustless consensus paradigm, it’s extremely energy intensive because of all the computing power required to solve hash problems. Also, while it was meant to be decentralized, it’s actually becoming more centralized as miners consolidate and massive mining setups eat up larger shares of winning blocks.
The Bitcoin Blockchain is a game changer, because it is public and permissionless. Anyone in the world can download the open source code, and can start verifying transaction, being rewarded with bitcoin, through a concept called mining. All stakeholders in the bitcoin network, who do not know and trust each other, are coordinated through an economical incentive framework pre-defined in the protocol and auto enforced by machine consensus of the P2P Network. The smart contract in the blockchain protocol therefore  provides an coordination framework for all network participants, without the use of traditional legal contracts. In private and permissioned blockchain, all network participants validating transactions are known. Bilateral or multilateral legal agreements provide a framework for trust, not the code.

Start mining on node 1 by using the function miner.start(1), where 1 refers to the number of threads. Note that the miner.start(n) function will always return "null." Unless you have many CPU cores, keep the thread number low to avoid high CPU usage. Note that mining without any pending transaction can still earn your default account incentive (ETH). It creates empty blocks, thus strengthening the integrity of the blockchain tree.


Sidechains are blockchains that allow for digital assets from one blockchain to be used securely in a separate blockchain and subsequently returned to the original chain. The term “sidechain” in this case is used for context, in that the paper initially refers to Bitcoin as the “parent chain” and connected blockchains (altcoins) as “sidechains,” but the term is interchangeable so that altcoins interacting with each other can each be a parent chain interacting with sidechains. You may have also heard of “childchains,” which are also sidechains.
The problem with Ethereum is that transactions are executed one after another. However, Aelf differs in its parallel computing blockchain capability. It scales transaction computing power inside a single side chain. Now imagine the power when you have thousands of side chains. For any unrelated transactions, it is safe to execute them concurrently.
First of all, one should not confuse private and public blockchains. They have one obvious similarity – they are blockchains, decentralized networks. Every participant of the network keeps a copy of this shared ledger, and all these copies are kept sync with the help of a certain consensus protocol. It means that all the participants of the network have access to identical information. Also, all the networks are immutable, and the information they contain can’t be altered.

Performance at scale: It is not uncommon for large businesses to process 100,000’s of transactions per second (TPS). Therefore, enterprise blockchains need to scale so that they can deliver performance accordingly. To achieve this, they can compartmentalize processes using containers or similar approaches. Read more about this requirement in this article “Enterprise blockchain ready to go live”.
A private blockchain network requires an invitation and must be validated by either the network starter or by a set of rules put in place by the network starter. Businesses who set up a private blockchain, will generally set up a permissioned network. This places restrictions on who is allowed to participate in the network, and only in certain transactions. Participants need to obtain an invitation or permission to join. The access control mechanism could vary: existing participants could decide future entrants; a regulatory authority could issue licenses for participation; or a consortium could make the decisions instead. Once an entity has joined the network, it will play a role in maintaining the blockchain in a decentralized manner.
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