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.
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“Such brazen theft would indicate [1] that Bitcoin would be (in the near future) without sidechains of any kind, and [2] that Bitcoin itself may be in danger from the miners (and we may need to consider using an alternate proof-of-work hash function),” he explained the impact of this setup in his original post on the topic. Like SPV sidechains, drivechains require a soft-forking change to Bitcoin.
thank you for the clear explanation of this. so in essence, by locking bitcoins to a particular address we’ve created an asset (collateral). then on the other sidechain (marketplace) we get issued shares against the asset, which we can sell. anyone holding a share can then redeem it against the asset. I think that’s an analogy that finance types would get
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 September 2015, the first peer-reviewed academic journal dedicated to cryptocurrency and blockchain technology research, Ledger, was announced. The inaugural issue was published in December 2016.[91] The journal covers aspects of mathematics, computer science, engineering, law, economics and philosophy that relate to cryptocurrencies such as bitcoin.[92][93]
Structure Side chains are independent blockchains that have a kind of "pegging mechanism", where at least one of the chains (main chain and side chain) is "aware" of the other chain and both tokens are pegged at a set ratio. Side chains need their own network security and block processing. "Child Chains" of the Ardor platform are tightly integrated into the main Ardor parent chain. All transactions are processed and secured by the parent chain forgers. This makes cross-chain transactions possible. Pruning will be enabled on child chain transactions in order to significantly reduce blockchain bloat by pruning the transactions on regular basis from the blockchain.
Developers and Cryptocurrency enthusiasts have been looking at expanding Bitcoins functionality as mainstream adoption increases. Side chains would increase the resilience of Bitcoin: If one of the sidechains was to be compromised, only the Bitcoins on that chain would be lost, while other sidechains and the Blockchain would continue like normal. This would further stabilize the Bitcoin network and increase security.
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.

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.


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.
Cuando esta transacción recibe las suficientes confirmaciones, se manda una notificación a la otra cadena de bloques (la que tú quieres utilizar) en el que se adjunta la prueba de que las monedas han sido enviadas por ti a esa dirección especial de la red. Tras ello, en la sidechain se creará, de forma automática, el mismo número exacto de activos que bitcoins se mandaron, dándote a ti el control de los mismos. Es decir, replica en el nuevo activo la cuantía que has enviado de la cadena principal a la sidechain. ¡Muy importante! Recordar que no se han creado o destruido nuevos bitcoins. Simplemente se han movido hasta que no estén usándose en la sidechain.
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The idea emerged that the Bitcoin blockchain could be in fact used for any kind of value transaction or any kind of agreement such as P2P insurance, P2P energy trading, P2P ride sharing, etc. Colored Coins and Mastercoin tried to solve that problem based on the Bitcoin Blockchain Protocol. The Ethereum project decided to create their own blockchain, with very different properties than Bitcoin, decoupling the smart contract layer from the core blockchain protocol, offering a radical new way to create online markets and programmable transactions known as Smart Contracts.
Public blockchains are also expensive, and not just in terms of money. The time and energy required to process transactions on public chains is more intensive than that of non-public chains. This is because every single node on the chain must authorize each new transaction before it is added to the chain, which requires a large amount of electricity and time (not to mention money).
A federation is a group that serves as the intermediary between a parent chain and its corresponding sidechain. It is an additional layer in the protocol but serves a key function and is what Blockstream’s Liquid sidechain uses. Due to the lack of expressiveness of Bitcoin’s scripting language, an externally implemented and mutually distrusting set of members form a federated peg.
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.
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.
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.”
Las sidechains son otro de los conceptos más famosos entorno a Bitcoin, no los pierdas de vista. La teoría indica que permitirían añadir funcionalidades nuevas a Bitcoin, pero sin necesidad de modificar constantemente el código de éste, ya que la funcionalidad es desarrollada utilizando otra cadena de bloque para finalmente ser conectada a la de Bitcoin. Al mismo tiempo esto evitaría la saturación de una sola cadena de bloques, como actualmente ocurre, al utilizar cadenas diferentes para cada caso de uso.
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.
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.

Decentralization and distribution are seen by many to be a major benefit of public blockchains, but not everybody shares this ethos. But this is not the only benefit of public blockchains, of course. Perhaps most importantly, their transparency makes them very secure: because they can be audited by anybody, it is easy to detect fraud on the chain. Security-via-openness is a principle well known in the open source world, and this strategy is also popular among some in the digital currency community. For example, all of the tools and content produced by the Ethereum team is open source. This helps to make Ethereum widely accessible and more secure.
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.

There is a whole other issue of identity theft that needs to be addressed. Just a short note here as this is a big subject: If the private key to identity object is stolen, the true owner of the identity needs to have a way to change the key. One approach to that would be to use the private key of the bitcoin transaction that created the first version of the identity object. Another way could be to prove the ownership of other public keys on the identity object, like the one used for encryption (PGP key management suggests a separate key for each purpose, signing, encryption, etc.). Other non-automatic ways could include a trusted third-party, social proof, etc.
In order to spend them, you have to prove you’re entitled to do so. And you do that by providing the solution to a challenge that was laid down when they were sent to you in the first place. This challenge is usually just: “prove to the world that you know the public key that corresponds to a particular Bitcoin address and are in possession of the corresponding private key”. But it can be more sophisticated than that.
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.

Governance: Every enterprise needs to design standards, processes, methods, and tools to develop and operate a private blockchain. To achieve this they will need tools and frameworks such as IDE, testing framework, security auditing tool etc. For long-term successful operation, they also need to develop high-quality documentation. This requires proactive governance. Read more about the importance of the “Fundamental challenges with public blockchains” here.
This comparison might make you think that private blockchains are more reasonable to use as they are faster, cheaper, and protect the privacy of their members. However, in certain cases, transparency is more crucial than the speed of transaction approval. So, every company interested in moving their processes to a blockchain evaluates the needs and goals and only then selects a particular type of distributed ledger.
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.”
Imagine over several hours, the camps produced a chain of messages that each required intensive Proof of Work. This means that the majority of the camps had to agree on this chain of messages and each camp can confidently trust the final outcome. It’s important to note here that Proof of Work does not care about the message itself, only that the nodes agreed to the final message. This majority network consensus keeps it secure and provides a solution to the Byzantine Generals Problem, leading to Byzantine Fault Tolerance.
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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]

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Structure Side chains are independent blockchains that have a kind of "pegging mechanism", where at least one of the chains (main chain and side chain) is "aware" of the other chain and both tokens are pegged at a set ratio. Side chains need their own network security and block processing. "Child Chains" of the Ardor platform are tightly integrated into the main Ardor parent chain. All transactions are processed and secured by the parent chain forgers. This makes cross-chain transactions possible. Pruning will be enabled on child chain transactions in order to significantly reduce blockchain bloat by pruning the transactions on regular basis from the blockchain.
Many blockchain enthusiasts believe in the value of networks that are not only decentralized — which most closely resembles the current model of the Internet — but distributed. This includes Tim Berners-Lee, who founded the World Wide Web in 1989. Berners-Lee has proposed that blockchains can be used to reinvent the web in a more distributed and peer-to-peer fashion.