@Tradle. Thanks for elaborating. I’m also thinking about these things – and hear lots of other people talk about them – but I *really* struggle with the concept. It all comes down to the table I drew in this post: https://gendal.me/2014/12/19/a-simple-model-to-make-sense-of-the-proliferation-of-distributed-ledger-smart-contract-and-cryptocurrency-projects/
– A consensus much faster: the fact that the consensus mechanism is centralized makes it much quicker. In fact, the term “consensus” is no longer adapted since it is rather a recording of transactions on the blockchain. Note that the entity responsible for managing the blockchain can decide to change the parameters of the blockchain and in particular to increase the size of the blocks to be able to add more transactions.
The block time is the average time it takes for the network to generate one extra block in the blockchain.[27] Some blockchains create a new block as frequently as every five seconds.[28] By the time of block completion, the included data becomes verifiable. In cryptocurrency, this is practically when the transaction takes place, so a shorter block time means faster transactions. The block time for Ethereum is set to between 14 and 15 seconds, while for bitcoin it is 10 minutes.[29]
The creation of sidechains have been a direct result of scalability issues associated with the main blockchain for projects such as Ethereum. Making sidechains increasingly popular way to speed up transactions. Lisk was the first decentralized application (dapp) to implement sidechains. With Lisk, each dapp created exists on its own sidechain without interfering with the mainchain.
In simple terms, public blockchains can receive and send transactions from anybody in the world. They can also be audited by anybody, and every node has as much transmission power as any other. Before a transaction is considered valid, it must be authorized by each of its constituent nodes via the chain’s consensus process. As long as each node abides by the specific stipulations of the protocol, their transactions can be validated, and thus add to the chain
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]

@quinn – thanks for the comment. I probably didn’t write clearly enough… I was trying to point out that none of the higher-level concepts we’re familiar with (addresses, bitcoins, the “ledger”, etc) actually exist at the protocol level…. it’s just transactions, transaction outputs, unspent transaction outputs, etc… they combine to create the illusion we’re all familiar with.


The sidechains vision of the future is of a vast globe-spanning decentralized network of many blockchains, an intertwined cable rather than a single strand, each with its own protocol, rules, and features — but all of them backed by Bitcoin, and protected by the Bitcoin mining network, as the US dollar was once backed by gold. Sidechains can also be used to prototype changes to the fundamental Bitcoin blockchain. One catch, though: this will require a small tweak to the existing Bitcoin protocol.
Note: Some would argue that such a system cannot be defined as a blockchain. Also, Blockchain is still in it’s early stages. It is unclear how the technology will pan out and will be adopted. Many argue that private or federated Blockchains might suffer the fate of Intranets in the 1990’s, when private companies built their own private LANs or WANs instead of using the public Internet and all the services, but has more or less become obsolete especially with the advent of SAAS in the Web2.
Unlike the other two-way peg mechanisms discussed in this article, SPV sidechains do not give direct control of real bitcoins on the main chain to a custodian; however, the ability for a majority of miners to produce and build upon fraudulent SPV proofs gives them indirect control over the funds, including the ability to send to themselves. Having said that, there are ways to mitigate this issue.
In simple terms, public blockchains can receive and send transactions from anybody in the world. They can also be audited by anybody, and every node has as much transmission power as any other. Before a transaction is considered valid, it must be authorized by each of its constituent nodes via the chain’s consensus process. As long as each node abides by the specific stipulations of the protocol, their transactions can be validated, and thus add to the chain
^ Jump up to: a b c d e f g h i j k l "Blockchains: The great chain of being sure about things". The Economist. 31 October 2015. Archived from the original on 3 July 2016. Retrieved 18 June 2016. The technology behind bitcoin lets people who do not know or trust each other build a dependable ledger. This has implications far beyond the crypto currency.
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.
The information on every public blockchain is subsequently replicated to sometimes thousands of nodes on the network. No one power administers it centrally, hence, hackers can’t destroy the network by crippling one central server. Read this article “What is Blockchain technology? A step-by-step Guide For Beginners”, for a more detailed description of the technology.
Send your Bitcoins to a specially formed Bitcoin address. The address is specially designed so that the coins will now be out of your control… and out of the control of anybody else either. They’re completely immobilized and can only be unlocked if somebody can prove they’re no longer being used elsewhere (I’ll explain what I mean by this in a minute).   In other words, you’ve used the core bitcoin transaction rules I described above to lay down a specific condition that the future owner – whoever it ends up being – needs to fulfil in order to take control
The block time is the average time it takes for the network to generate one extra block in the blockchain.[27] Some blockchains create a new block as frequently as every five seconds.[28] By the time of block completion, the included data becomes verifiable. In cryptocurrency, this is practically when the transaction takes place, so a shorter block time means faster transactions. The block time for Ethereum is set to between 14 and 15 seconds, while for bitcoin it is 10 minutes.[29]
Peer-to-peer blockchain networks lack centralized points of vulnerability that computer crackers can exploit; likewise, it has no central point of failure. Blockchain security methods include the use of public-key cryptography.[4]:5 A public key (a long, random-looking string of numbers) is an address on the blockchain. Value tokens sent across the network are recorded as belonging to that address. A private key is like a password that gives its owner access to their digital assets or the means to otherwise interact with the various capabilities that blockchains now support. Data stored on the blockchain is generally considered incorruptible.[1]
“The reason why you put up private blockchains is potentially because you want to have control over the participants in the blockchain. So as we have banks and financial institutions, who have to worry heavily about regulations, they can’t use the public blockchains right now because they are open and permission-free, and anyone can participate, and that’s contradictory to the regulations to which they must abide.

Por ello, con este escenario sobre la mesa y con el objetivo de aunar esfuerzos, algunos se han preguntado: ¿Sería posible crear blockchains que sean utilizadas para casos de usos concretos, pero conectadas en todo momento a la de Bitcoin? ¿Podemos crear piezas de software que desde una blockchain se pueda saltar a otra de manera transparente, segura y descentralizada? Esto generaría, para que te hagas una imagen mental, algo así como las ruedas dentadas interconectadas de un motor, cada rueda una blockchain, todas trabajando juntas.


Implemented by The initial design was published by Blockstream in 2014, but the implementation is blocked by the lack of native support for SPV proofs in Bitcoin (which may not be added at all). Rootstock workaround this by sacrificing decentralization (still work in progress). The Ardor platform created by Jelurida is the first to propose and implement the concept of Child Chains. Already running on testnet, the production Ardor launch is scheduled for Q4 2017.


It may sound nitpicky, but I think that description leaves something to be desired in terms of presenting the “correct” mental model. First, there is no such thing as “a” bitcoin, as I am sure the author would agree. Speaking of spending or moving bitcoins perpetuates the notion of bitcoins as “things”. It might be preferable to say that you are spending or moving “units of the bitcoin protocol”. There is something similar going on here with dollars. The dollars in your bank account aren’t things either, they are units of demand or claim on a currency. The fact that printed dollars have serial numbers tends to confuse this notion. Treating something as a “thing’ which is not a thing is sometimes referred to as the reification fallacy.
Thus Tradle set out to build a meta-protocol that saves the data in the overlay network, and only puts minimal referencing data on the blockchain. There is a general grumpy consensus among bitcoin core devs and mining pool operators on allowing one small data chunk, a hash, per transaction. Many devs say it is not possible to secure this second overlay network. I agree, unless we use the blockchain to help with the task. We have a partial solution working, and are preparing a new design to improve it (partial, as it can not yet handle all known attacks). We are actively sharing the designs at various meetups (and on the github) and are inviting devs to find attack vectors and propose solutions. Tradle’s protocol not only relieves the pressure on bitcoin’s blockchain but is also able to handle larger transaction sizes than Counterparty and Mastercoin, so it can be used for complex identity, supply chain management and many other applications. It is also capable of handling attachment files, needed in the healthcare and financial industries.
A Sidechain, in simplest terms, is just a separate blockchain but is attached to the parent through the use of a two-way peg which allows for assets to be interchangeable and moved across the chain at a fixed deterministic exchange rate. This two-way peg works by utilizing simple payment verification or SPV as it's otherwise known. To show and prove ownership of the assets on the parent chain.
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Alpha functions as a sidechain to Bitcoins testnet. The peg mechanism currently works through a centralized protocol adapter, as stated in the sidechains whitepaper. An auditable federation of signers manages Testnet coins transferred to the sidechain. The federation is also relied upon to produce blocks through the signed blocks element. This creates the possibility of exploring the possibilities of the new chain using different security trade-offs.
Let's explore if there is a hybrid blockchain concept (third type). A consortium blockchain would be a mix of both the public and private. Wherein the ability to read & write could be extended to a certain number of people/nodes. This could be used by groups of organization/firms, who get together, work on developing different models by collaborating with each other. Hence, they could gain a blockchain with restricted access, work on their solutions and maintain the intellectual property rights within the consortium.
Aelf uses a consensus algorithm called DPoS (Delegated Proof of Stake) that takes the best of both cooperative and competitive consensus algorithms. DPoS uses votes from stakeholders to achieve consensus. The competitive part is larger stakeholders having an influence on their delegate of choice. The delegates that have the most votes will take their turn to produce a block cooperatively in a sequence. DPoS makes transactions permanent. A rollback isn’t possible so a confirmation can be fast. DPoS is also scalable because anyone can participate in the consensus. Additionally, DPoS is environmentally friendly because electricity isn’t wasted like in Proof of Work.
This approach isn’t fool-proof, but it’s not by mistake that the system looks the way it does today (that’s my history degree talking). Despite best technical efforts, human problems remain within the realm of probability. From http://www.nytimes.com/2009/01/15/books/15masl.html: “…blame cannot be easily assigned: not even the most sophisticated economists of the era could accurately predict disaster, let alone guard against it. The effects of a public herd mentality at the time of the [insert catastrophe here] are depicted, all too recognizably, as unstoppable.”
• ‘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.

Sidechains allow cryptocurrencies to interact with one another. They add flexibility and allow developers to experiment with Beta releases of Altcoins or software updates before pushing them on to the main chain. Traditional banking functions like issuing and tracking ownership of shares can be tested on sidechains before moving them onto main chains. If the security mechanisms for sidechains can be bolstered, sidechain technology holds promise for massive blockchain scalability.
Jump up ^ Kopfstein, Janus (12 December 2013). "The Mission to Decentralize the Internet". The New Yorker. Archived from the original on 31 December 2014. Retrieved 30 December 2014. The network's 'nodes'—users running the bitcoin software on their computers—collectively check the integrity of other nodes to ensure that no one spends the same coins twice. All transactions are published on a shared public ledger, called the 'block chain.'
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]

2. Ardor’s Blockchain as a service platform for business: Ardor uses the Proof of Stake consensus mechanism. Ardor calls its sidechains ‘childchains’, and they are tightly integrated into the main chain. Security is enhanced because all transactions are processed and secured by parent chain forgers. Most transactions are pushed down to the childchain level, as the parent mainchain retains minimal features. Global entities such as assets and currencies across chains can be accessed through childchains.

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.
Bitcoin está demostrando un potencial enorme, y desarrolladores de todo el mundo quieren llevar esta tecnología aún más lejos, por ejemplo con los smart contracts turing completo o las llamadas smart property. El problema es que Bitcoin tiene un lenguaje de programación deliberadamente limitado. Además sus transacciones se confirman relativamente despacio, cada 10 minutos. Y ya por último y muy importante, su cadena de bloques está saturándose de transacciones debido a la creciente fama de Bitcoin.
2. Ardor’s Blockchain as a service platform for business: Ardor uses the Proof of Stake consensus mechanism. Ardor calls its sidechains ‘childchains’, and they are tightly integrated into the main chain. Security is enhanced because all transactions are processed and secured by parent chain forgers. Most transactions are pushed down to the childchain level, as the parent mainchain retains minimal features. Global entities such as assets and currencies across chains can be accessed through childchains.
For example, Banks A and B often settle thousands of transactions per day. It would be extremely expensive for all of those transactions to be committed to the main blockchain, so A and B set up a side-chain. At the end of each day, at most one transaction is committed to the main blockchain (the only possible outcomes are A and B's balances remain the same, or one of their balances decreases and the other's increases).
“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, e.g. 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….