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.”
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.
What is the difference between a public blockchain and a private blockchain? Does it matter? Which is better? Gallactic believes that currently there are pros and cons between both Private and Public Blockchains, but time and “convergence”, a term that is gaining prominence in the Blockchain Industry, is clearly showing that the lines between these categories, once clear, are starting to fade.

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.


“Such a move could allow retailers to lower prices and incentivize consumers to shop at one retailer over a competitor,” Cohen noted. “This idea is not as ludicrous as it might seem. Amazon recently registered three cryptocurrency-related domain names, suggesting a potential move into the cryptocurrency space. If large companies like Amazon, Walmart or Starbucks issued digital coins that inspired public trust, blockchain-based cryptocurrencies might gain acceptance by the public and other retail giants.”
The NPD report noted IBM is partnering with nine retailers and food companies (Walmart, Unilever, Nestle, Dole, Tyson Foods, Golden State Foods, McCormick & Co., McLane Co., and Driscoll’s) to revamp data management processes with blockchain. Walmart uses blockchain in China to source its pork all the way from the pig to the customer. This enables the retailers to provide transparency to all the players along the supply chain.
Transparency does not, however, mean that public blockchains are completely unhackable. Any time data enters a digital network, it is subject to security breaches and unethical uses. Although public blockchains looks to be highly secure right now, there are always going to be bad actors interested in exploiting weaknesses in the system. This is often through hacking methods that are difficult to predict and account for — so claims of one-hundred-percent security in any technology should always be read with a critical eye
Side chains have two main advantages. Their first advantage they have is that they are permanent. You do not have to create a new sidechain every time you need to use one. Once a side chain is built, it is maintained and can be used by anyone doing a specified task off the main chain. The other advantage of sidechains is that they allow interaction between different cryptocurrencies. Developers get the opportunity to test software upgrades as well as beta coin releases before they are released on the main chain.
“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.” 
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.
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.

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.”
As you can see, several of these real-world demands for the evolution of the initial Bitcoin implementation are still highly relevant. Trade-offs between scalability and decentralization are demonstrated with Ethereum’s focus on decentralization first and resulting complexities in developing scalable solutions. The increased emphasis on smart contract functionality, pegging real-world assets to blockchains, and experimentation of altcoins that are currently ongoing also represent the forward-thinking ideas outlined in the paper.
Over the last year the concept of “private blockchains” has become very popular in the broader blockchain technology discussion. Essentially, instead of having a fully public and uncontrolled network and state machine secured by cryptoeconomics (eg. proof of work, proof of stake), it is also possible to create a system where access permissions are more tightly controlled, with rights to modify or even read the blockchain state restricted to a few users, while still maintaining many kinds of partial guarantees of authenticity and decentralization that blockchains provide. Such systems have been a primary focus of interest from financial institutions, and have in part led to a backlash from those who see such developments as either compromising the whole point of decentralization or being a desperate act of dinosaurish middlemen trying to stay relevant (or simply committing the crime of using a blockchain other than Bitcoin). However, for those who are in this fight simply because they want to figure out how to best serve humanity, or even pursue the more modest goal of serving their customers, what are the practical differences between the two styles?

By the end of this post, you’ll be able to freely participate in conversations like the above. This is not a coding tutorial, as we’ll just be presenting important concepts at a high level. However, we may follow up with programming tutorials on these ideas. This article will be helpful to both programmers and non-programmers alike. Let’s get going!

A public blockchain is ideal when the network must be truly decentralized, which means that no central entity controls the entry of the members on the network and the consensus mechanism is democratic. A democratic mechanism of consensus means that all members can become a minor and that these miners are in competition to add the blocks to the blockchain (at least when the mechanism of the evidence of the work is used).
Side-chain is another blockchain for one blockchain. To use side-chain of Bitcoin, for instance, you need to move BTC from the original chain to the side-chain. Then, BTC on the original chain is locked and the same amount of BTC on the side-chain appears. This is how BTC can be used/tested on another chain where we use some features different from the original ones.
“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.
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.

As you can see, several of these real-world demands for the evolution of the initial Bitcoin implementation are still highly relevant. Trade-offs between scalability and decentralization are demonstrated with Ethereum’s focus on decentralization first and resulting complexities in developing scalable solutions. The increased emphasis on smart contract functionality, pegging real-world assets to blockchains, and experimentation of altcoins that are currently ongoing also represent the forward-thinking ideas outlined in the paper.
Setting up an environment to test and research blockchain requires an ecosystem with multiple systems to be able to develop research and test. The big players in the cloud industry like Amazon(AWS), Microsoft(Azure), IBM(BlueMix) have seen the potential benefits of offering blockchain services in the cloud and started providing some level of BaaS to their customers. Users will benefit from not having to face the problem of configuring and setting up a working blockchain. Hardware investments won’t be needed as well. Microsoft has partnered with ConsenSys to offer Ethereum Blockchain as a Service (EBaaS) on Microsoft Azure. IBM(BueMix) has partnered with Hyperledger to offer BaaS to its customers. Amazon announced they would be offering the service in collaboration with the Digital Currency Group. Developers will have a single-click cloud-based blockchain developer environment, that will allow for rapid development of smart contracts.

Cabe destacar el papel de la gente de Blockstream, una de las compañías centradas en la búsqueda de este objetivo (con un extremeño en sus filas, Jorge Timón). Blockstream está trabajando actualmente en el desarrollo de un protocolo que permita crear sidechains. Son los responsables de uno de los papers más conocidos sobre el tema, publicado en Octubre del 2014:
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.
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.
Public blockchains are open, and therefore are likely to be used by very many entities and gain some network effects. To give a particular example, consider the case of domain name escrow. Currently, if A wants to sell a domain to B, there is the standard counterparty risk problem that needs to be resolved: if A sends first, B may not send the money, and if B sends first then A might not send the domain. To solve this problem, we have centralized escrow intermediaries, but these charge fees of three to six percent. However, if we have a domain name system on a blockchain, and a currency on the same blockchain, then we can cut costs to near-zero with a smart contract: A can send the domain to a program which immediately sends it to the first person to send the program money, and the program is trusted because it runs on a public blockchain. Note that in order for this to work efficiently, two completely heterogeneous asset classes from completely different industries must be on the same database - not a situation which can easily happen with private ledgers. Another similar example in this category is land registries and title insurance, although it is important to note that another route to interoperability is to have a private chain that the public chain can verify, btcrelay-style, and perform transactions cross-chain.

Sidechain is a chain of blocks based on the main parental blockchain. Sidechains realize the new financial ecosystems via integration into Bitcoin. Relatively new to Bitcoin, the sidechain is an extension that enables the ability both to build a link between BTC and an altcoin and to create new independent services that work via the main Bitcoin blockchain. Using sidechains allows for the creation of various types of smart contracts, stocks, derivatives, etc. It is possible to develop a limitless number of Bitcoin or Ethereum-based sidechains with different tasks and features, assets of which will depend on the main blockchain’s volatility. It allows traditional blockchains to support several kinds of assets, payments, smart contracts and also to increase the level of security and anonymity of transactions.
The Blockstream Satellite network broadcasts the Bitcoin blockchain to the entire planet. The satellite network provides an opportunity for nearly 4 billion people without Internet access to utilize bitcoin while simultaneously ensuring bitcoin use is not interrupted due to network interruption. Utilizing the latest open source Software Defined Radio (SDR) technologies, the Blockstream Satellite network offers a breakthrough in the cost effectiveness of satellite communications.
This segment is where we have seen the most rapid metamorphosis in the past year, mostly in financial services. These solutions are industry-specific, and they are based on private blockchain or ledger infrastructures. A caveat here is that some of these are not full blockchains. Rather, they are distributed ledgers, which are a subset of blockchain capabilities. And some don’t even include a consensus element, which takes the implementation another level down from distributed ledger tech.

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.
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.

“RSK directly “plugs in” to achieve a perfect merged-mining and to ensure that cryptographic work, that will be discarded in Bitcoin mining, is reused in the first smart contract open-source platform secured by the Bitcoin network. RSK has an agreement with Bitcoin miners: we share with them 80% of the fees arising from transactions made within the smart contract network.”

This segment is where we have seen the most rapid metamorphosis in the past year, mostly in financial services. These solutions are industry-specific, and they are based on private blockchain or ledger infrastructures. A caveat here is that some of these are not full blockchains. Rather, they are distributed ledgers, which are a subset of blockchain capabilities. And some don’t even include a consensus element, which takes the implementation another level down from distributed ledger tech.
“Further, contribution is weighted by computational power rather than one threshold signature contribution per party, which allows anonymous membership without risk of a Sybil attack (when one party joins many times and has disproportionate input into the signature). For this reason, the DMMS has also been described as a solution to the Byzantine Generals Problem[AJK05].”
@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 NPD report noted IBM is partnering with nine retailers and food companies (Walmart, Unilever, Nestle, Dole, Tyson Foods, Golden State Foods, McCormick & Co., McLane Co., and Driscoll’s) to revamp data management processes with blockchain. Walmart uses blockchain in China to source its pork all the way from the pig to the customer. This enables the retailers to provide transparency to all the players along the supply chain.
The term “sidechains” was first described in the paper “Enabling Blockchain Innovations with Pegged Sidechains”, circa 2014 by Adam Back et al. The paper describes “two-way pegged sidechains”, a mechanism where by proving that you had “locked” some coins that were previously in your posession, you were allowed to move some other coins within a sidechain.
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.
– A cost per transactions which can be high: Miners only participate in the process of mining because they hope to get the reward (coinbase and fees) allocated to minors who have added a block to the blockchain. For them it is a business, this reward will finance the costs they have incurred in the process of mining (electricity, computer equipment, internet connection). Tokens that are distributed to them are directly issued by the Protocol, but the fees are supported by the users. In the case of the bitcoin, for example, minors receive 12.5 bitcoins for each block added, to which are added fees paid by the users to add their transactions to the blocks. These fees are variable and the higher the demand to add transactions, the higher the fees.
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”.

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.
Elements Alpha functions as a sidechain to Bitcoin’s testnet, though the peg mechanism currently works through a centralized protocol adapter, as described in the Sidechains whitepaper. It relies on an auditable federation of signers to manage the testnet coins transferred into the sidechain via the “Deterministic Pegs” Element, and to produce blocks via the “Signed Blocks” Element. This makes it possible to immediately explore the new chain’s possibilities, using different security trade-offs. They plan to, in a later release, upgrade the protocol adapter to support fully decentralized merge-mining of the sidechain, and ultimately to phase in the full 2-way peg mechanism.
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.
The immense promise and accelerated development of permissioned blockchain technology, combined with intense business interest from a wide range of industries, is acting as a perfect stimulant for more and more enterprises to start rolling out blockchain networks into production. I envision these permissioned networks will soon directly or indirectly influence every facet of human enterprise.
×