Sidechain transactions using a two-way peg effectively only allow for intra-chain transactions. A transfer from Bitcoin (parent chain) to Ethereum (sidechain) would allow a user to use the functionality of Ethereum (i.e., fully expressive smart contracts), but the underlying original asset would remain precisely that, Bitcoin. So, a Bitcoin on an Ethereum sidechain technically remains a Bitcoin.
@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
The consensus mechanism involves ascertaining transaction validity and uniqueness. Smart contracts address the validity portion. To ensure uniqueness, the protocol program in Corda checks whether any other transaction has used any of the input states of this transaction. If no other transaction has used any of the input states, that this transaction is unique.
Looking for a top private blockchain open source? Here is a list of private blockchain development companies with client reviews and ratings. Private blockchain network on contrary to public and permission blockchain can be run and utilized by one organization only. Additionally, private blockchain platform organizes distinctive components of the technology in order to serve different applications. By prioritizing productivity over the secrecy, permanence, and transparency, private blockchain open source adheres to the qualities normally connected with the technology. The scope of uses for private blockchain might be narrow yet its power to enhance processes are no less important. GoodFirms has thus created a list of top private blockchain companies below:
Unfortunately our second option cannot be done yet, because to use these sidechains, main chain (here it is bitcoin) needs to do some upgrade (soft fork). By the way, upgrades in public blockchains are very painful yet. There will be a user activated soft fork (UASF) on August 1. All bitcoin forms’ trend topic is this soft fork which is about a code change for Segregated Witness Adoption.
The good thing about sidechains is that they are independent of their main chain. Sidechains take care of their own security. Problems occurring on the sidechain can, therefore, be controlled without affecting the main chain. Likewise, a security problem on the main chain does not affect the sidechain although the value of the peg is greatly reduced.
Sometimes separate blocks can be produced concurrently, creating a temporary fork. In addition to a secure hash-based history, any blockchain has a specified algorithm for scoring different versions of the history so that one with a higher value can be selected over others. Blocks not selected for inclusion in the chain are called orphan blocks.[22] Peers supporting the database have different versions of the history from time to time. They keep only the highest-scoring version of the database known to them. Whenever a peer receives a higher-scoring version (usually the old version with a single new block added) they extend or overwrite their own database and retransmit the improvement to their peers. There is never an absolute guarantee that any particular entry will remain in the best version of the history forever. Because blockchains are typically built to add the score of new blocks onto old blocks and because there are incentives to work only on extending with new blocks rather than overwriting old blocks, the probability of an entry becoming superseded goes down exponentially[23] as more blocks are built on top of it, eventually becoming very low.[1][24]:ch. 08[25] For example, in a blockchain using the proof-of-work system, the chain with the most cumulative proof-of-work is always considered the valid one by the network. There are a number of methods that can be used to demonstrate a sufficient level of computation. Within a blockchain the computation is carried out redundantly rather than in the traditional segregated and parallel manner.[26]
A side-chain is a separate block-chain that runs parallel to the main chain, for example the Bitcoin network, and is attached to the main chain through a simple two-way peg, or special 'address'. A user sends coins to this special address and this amount is effectively 'locked' out from use on the main chain and available on the side chain. This currency is released back to the main chain once its been proven that the side chain is no longer using it.
Nikolai Hampton pointed out in Computerworld that "There is also no need for a '51 percent' attack on a private blockchain, as the private blockchain (most likely) already controls 100 percent of all block creation resources. If you could attack or damage the blockchain creation tools on a private corporate server, you could effectively control 100 percent of their network and alter transactions however you wished."[9] This has a set of particularly profound adverse implications during a financial crisis or debt crisis like the financial crisis of 2007–08, where politically powerful actors may make decisions that favor some groups at the expense of others,[51][52] and "the bitcoin blockchain is protected by the massive group mining effort. It's unlikely that any private blockchain will try to protect records using gigawatts of computing power—it's time consuming and expensive."[9] He also said, "Within a private blockchain there is also no 'race'; there's no incentive to use more power or discover blocks faster than competitors. This means that many in-house blockchain solutions will be nothing more than cumbersome databases."[9]

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 a cooperative consensus algorithm, there is a fixed number of voters. Voters cannot leave and join randomly. All voters know each other and every voter has only one vote. If the majority agree on the value of the data, then the system is working as designed. This can handle over 30,000 transactions per second. Scaling the number of voters can be an issue, because every vote proposed by a voter must be delivered to every other voter in the consortium.

Further, despite sidechains being independent of each other, they are responsible for their individual security and need the requisite mining power to remain secure. Bitcoin’s blockchain has sufficient PoW mining power to remain secure even from the most coordinated of attacks, but many more nascent sidechains lack the necessary network effects and mining power to guarantee security to users.
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Liquid is the world's first federated sidechain that enables rapid, confidential, and secure bitcoin transfers. Participating exchanges and Bitcoin businesses deploy the software and hardware that make up the Liquid network, so that they can peg in and out of the Bitcoin blockchain and offer Liquid’s features to their traders. Liquid provides a more secure and efficient system for exchange-side bitcoin to move across the network.
Incorporated in 2009 and headquartered in the USA, OpenXcell is an industry-leading software and mobile app development company known for delivering innovative software solutions and engaging mobile apps. Due to our unstoppable quest for making perfect mobile and web apps, we have slowly evolved into a one stop destination for all mobile and web app development needs. We have made a stellar reputation in the technology industry by adhering to ... Read more

Ethereum, a provider of decentralized platform and programming language that helps running smart contracts and allows developers to publish distributed applications. Factom, a provider of records management, record business process for business and governments. Blockstream, a provider of sidechain technology, focused on extending capabilities of Bitcoin. The company has started experimenting on providing accounting (considered a function to be done on private blockchain) with the use of public blockchain technology.
NPD said the next step for retailers is to develop their own cryptocurrency to prevent customers from having to use credit cards when shopping online. NPD said the practice makes sense for the retailer, because if the customer could send the payment transfer via blockchain, it would avoid third-party clearing house fees retailers pay for processing card payments.
In this case, you work directly with the given blockchain tools and stack. Assembly is required, so this isn’t for the faint of heart at this point, as many of the technologies are still developing and evolving. However, working directly with the blockchain provides a good degree of innovation, for example in building decentralized applications. This is where entrepreneurs are creating ambitious end-to-end, peer-to-peer applications, such as OpenBazaar (on Bitcoin), or Ujo Music (on Ethereum).

My chief concern is not with the concept of side chains per se (yet). I have still much to learn about how they are being considered. I am only concerned with the way the concept is being presented here. However, I am sure that much of this was due to space restrictions as much as anything. The concept of side chains is an intriguing one. It is also clearly attempting to address a major problem with the whole Bitcoin scheme- namely the verification latency it introduces for transactions. This is only one of the hurdles facing Bitcoins acceptance into the world of commerce, but it is a considerable one.
The Cryptocurrency Data Feed, a partnership between Blockstream and Intercontinental Exchange (ICE), offers traders best in class real-time and historical cryptocurrency data from a strong and growing list of exchange partners worldwide. With over 25 exchanges, 133 crypto and fiat currency pairs, and over 200M order book updates every day, the Cryptocurrency Data Feed is the most comprehensive and robust source of global cryptocurrency data.
Anyway, new blocks do not appear on the blockchain all of a sudden – the network must achieve consensus. In other words, each transaction must be validated by the rest of the network members, so-called “nodes.” Their contribution to the final decision on consensus is equal. Each node solves a complex cryptographic problem, and when a solution is found a new block appears on the blockchain. Such algorithm is called “proof-of-work consensus protocol.”

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.
Jump up ^ Epstein, Jim (6 May 2016). "Is Blockchain Technology a Trojan Horse Behind Wall Street's Walled Garden?". Reason. Archived from the original on 8 July 2016. Retrieved 29 June 2016. mainstream misgivings about working with a system that's open for anyone to use. Many banks are partnering with companies building so-called private blockchains that mimic some aspects of Bitcoin's architecture except they're designed to be closed off and accessible only to chosen parties. ... [but some believe] that open and permission-less blockchains will ultimately prevail even in the banking sector simply because they're more efficient.
– The manipulation of the blockchain: It is indeed possible to come back at any time on the transactions that have already been added to the blockchain and therefore change the balance of the members. In a public blockchain, such operation would require that 51% of the hashing power (i.e capacity to mine) is concentrated in the hands of the same entity. This not theory anymore since it happened beginning 2014 when the cooperative of GHash minor reached the 51% threshold.
Instead of adding new features directly to the bitcoin blockchain, sidechains allow developers to attach new features to a separate chain. Since the chains are still attached to the bitcoin blockchain, the features can take advantage of the cryptocurrency's network effects and test those applications, without harming the main network should vulnerabilities arise.

There has been tremendous interest in blockchain, the technology on which Bitcoin functions. Nakamoto developed the blockchain as an acceptable solution to the game theory puzzle – Byzantine General’s Problem. This lead to a number of firms adopting the technology in different ways to solve real world issues, wherever there was an element of trust involved. Majority of them could be relating to the ability to provide proof of ownership – for documents, software modules/licenses, voting etc.


The consortium or company running a private blockchain can easily, if desired, change the rules of a blockchain, revert transactions, modify balances, etc. In some cases, eg. national land registries, this functionality is necessary; there is no way a system would be allowed to exist where Dread Pirate Roberts can have legal ownership rights over a plainly visible piece of land, and so an attempt to create a government-uncontrollable land registry would in practice quickly devolve into one that is not recognized by the government itself. Of course, one can argue that one can do this on a public blockchain by giving the government a backdoor key to a contract; the counter-argument to that is that such an approach is essentially a Rube Goldbergian alternative to the more efficient route of having a private blockchain, although there is in turn a partial counter-argument to that that I will describe later.

Blockstream has also released an “Alpha” sidechain with all of those features up and running except the last, coupled to the Bitcoin testnet. (Used for testing Bitcoin software without putting real value at risk.) In the absence of the Bitcoin protocol change that will cryptographically secure the programmatic transfer of value between Bitcoin and sidechains, they’re cooperating with several external organizations to perform and validate those transfers. If and when that protocol change happens, though, pegged sidechains will be as permissionless, and as decentralized, as Bitcoin itself.

They rely on a technology called SPV (simplified payment verification) proofs, which work like this: in order to send money to a sidechain and back to the main bitcoin network again, users need to attach a proof that they really have the funds. Without these proofs, when users or miners move their money back to the main chain, under certain conditions, they could take more money than they really have.
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.