Saying that, Interoperability has been the missing link in conquering the obstacles faced by both private and public blockchains by empowering them to interact and exchange values across platforms seamlessly. Developers use of the Gallactic blockchain technology, that allow for private and public blockchains within its eco-system, will drive the potential to combine both public and private blockchains with innovative new solutions, designed to accomplish cross-chain exchange and greater compatibility is the way forward for all parties and their concerns.
Necessity is the answer to that question, well for the short term anyway. Currently public & private blockchains still have a lot of challenging technological problems that need to be sorted out, with privacy and scalability being foremost. Gallactic’s blockchain can certainly help with scalability due to its multi-chain architecture that allows for massive scaling to rival and in most cases surpass other blockchains in the market with transactions at 300 per second on mainchain with the ability to scale up to hundreds of thousands per second when the multi-chain model is configured for speed.
A big thanks to Diego Salvador for helping me write this episode. Him and the rest of the team over at Rootstock are doing fantastic work with cryptocurrency and Sidechains. We wish them all the best. I'll be sure to leave a link to their website in the top of the description so you can go check it out and learn more if you wish. And as always, be sure to subscribe and I will see you next time.
@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.
2) Yes – I had to keep things short/simple in this intro article in order to get across the key ideas. But you’re right: the sidechains need to be secured. But how that happens is a matter for the sidechain. If somebody can produce a false “proof” that the locked Bitcoins should be released on the Bitcoin side then that’s a problem for the sidechain, of course (somebody presumably just had their coins stolen!) but it’s irrelevant (at a macro level) on the Bitcoin side.
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 cheapest and most simple option is doing calculations on your local network (off-chain) and integrating with main blockchain by sending the results. It has flaws; you cannot live full advantage of blockchain as we do in bitcoin, because you will still have existing constraints of your current system. Despite all this, it is still a valid option; perhaps you won't need all the features of blockchain technology. Perhaps it is just enough to use blockchain only for your pain points. Factom can be considered under that kind of option. They used bitcoin wisely in their design. They hold the actual mass data in their network and utilize stability of bitcoin in their solution. This project is so successful that at coindesk magazine, it is saying that Factom can be used for the land titles in Honduras.
Confidential Transactions — At present, all Bitcoin transactions are completely public, albeit pseudonymous. Confidential Transactions, as the name implies, conceal the amount being transferred to all except the sender, the recipient, and others they designate. The resulting transaction size is significantly larger, but includes a sizable “memo” field that can be used to store transaction or other metadata, and is still smaller than eg Zerocoin.(Note that this isn’t as confidential as Zerocash, which conceals both the amount and the participants involved in any transaction, through the mighty near-magic of zk-Snarks. Mind you, Zerocash would require an esoteric invocation ritual to initiate its network. No, really. But that’s a subject for a separate post.)
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.
“Not only is decentralization, open protocols, open source, collaborative development and living in the wild a feature of Bitcoin, that’s the whole point. And if you take a permissioned ledger and say, that’s all nice, we like the database part of it, can we have it without the open decentralized P2P [peer-to-peer] open source non-controlled distributed nature of it, well you just threw out the baby with the bathwater.” 
Blockstream recently released a whitepaper on “strong federations,” which is essentially their vision of a federated two-way peg system. Liquid is a sidechain created by Blockstream that uses the strong federations model. The sidechain is used to transfer bitcoins between centralized bitcoin institutions, such as exchanges, at a faster pace than the public Bitcoin blockchain.
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.
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.

An important distinction to be made about sidechains that needs to be understood is that sidechains themselves help to fuel innovation through experimentation. Rather than providing scalability directly, they allow for trivial experimentation on sidechains with various scalability mechanisms. Using sidechains, one can avoid the problems of initial distribution, market volatility, and barriers to entry when experimenting with altcoins due to the inherent derivation of their scarcity and supply from Bitcoin. That being said, each sidechain is independent and flexible to tool around with various features.
“What is private blockchain?” is a logical question to ask after you found out that there is no such thing as one transcendental blockchain. What makes private networks different from the public is that only a selected group of people can access them. Hence, a random person has no chance to join a private ledger all of a sudden. To do so, a new participant needs an invitation or permission that can be issued by:
A blockchain is a distributed computing architecture where every node runs in a peer-to-peer topology, where each node executes and records the same transactions. These transactions are grouped into blocks. Each block contains a one-way hash value. Each new block is verified independently by peer nodes and added to the chain when a consensus is reached. These blocks are linked to their predecessor blocks by the unique hash values, forming a chain. In this way, the blockchain’s distributed dataset (a.k.a. distributed ledger) is kept in consensus across all nodes in the network. Individual user interactions (transactions) with the ledger are append-only, immutable, and secured by strong cryptography. Nodes in the network, in particular the public network, that maintain and verify the transactions (a.k.a. mining) are incentivized by mathematically enforced economic incentives coded into the protocol. All mining nodes will eventually have the same dataset throughout.
The second option will be to use sidechains. Blockstream first announced side chain in 2014 and published its whitepaper ( I believe in the future, bitcoin will have its desired flexibility with its sidechains. The idea of the sidechain is you can innovate and design your solution freely in the sidechains. These sidechains are independent, if they are failed or hacked, they won't damage other chains. So damage will be limited within that chain, for that reason you can be less conservative. Otherwise you would be more risk averse, if you had 42.5 billion dollar market cap like Bitcoin.
A consortium blockchain is often said to be semi-decentralized. It, too, is permissioned but instead of a single organization controlling it, a number of companies might each operate a node on such a network. The administrators of a consortium chain restrict users' reading rights as they see fit and only allow a limited set of trusted nodes to execute a consensus protocol.

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]
It might seem that this technology is beneficial for any business, but it is not. Quite often projects fail to justify their will of public or private blockchain implementation. The key reason to use blockchain is the inefficiency of existing centralized solution that is slow, expensive, and lacks transparency and reliability. In other cases, blockchain isn’t required.
As you know, we at LTP have been doing a lot of research to understand other use cases of blockchain apart from Bitcoin-based payments. Recently we had released a comprehensive analysis of 50+ startups and 20 use-cases of blockchain. Though there have been news of large companies accepting bitcoin (Ex.: Amazon, Microsoft, Dell) and the overall acceptance reaching a 100,000+ merchants figure, upon deeper examination we realize that large corporations do not store the Bitcoin payments. They generally partner with a Bitcoin payment processor who converts the Bitcoins to cash as and when they receive a payment and this converted amount is what the corporates take into their account. What a bummer!
Sidechains interactuando con blockchain. Blockstream explica en su paper como, a las sidechains, se les añade una nueva pieza llamada two-way peg. Two-way peg es “el conector” entre ambas cadenas y se encarga de hacer la “magia” para que los bitcoins “salten” a la otra cadena. Juntando ambas cosas obtenemos las pegged sidechain: cadenas laterales conectadas en todo momento. En la imagen puedes observar como, incluso, las sidechain pueden interactuar entre ellas. ¿Llegaremos a un escenario de blockchains interactuando con aspecto fractal?
This construction is achieved by composing smart contracts on the main blockchain using fraud proofs whereby state transitions can be enforced on a parent blockchain. We compose blockchains into a tree hierarchy, and treat each as an individual branch blockchain with enforced blockchain history and MapReducable computation committed into merkle proofs. By framing one’s ledger entry into a child blockchain which is enforced by the parent chain, one can enable incredible scale with minimized trust (presuming root blockchain availability and correctness).
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.
Are there any legitimate uses for it? Possibly, if you have an institution that can’t establish legal relationship between them. I am not sure where can we find this use case in the wild; most corporations and institutions usually thrive on the legal documents they have signed in order to keep each other from lying/hiding/deleting/changing data. Since each institution can keep the local copy of all transactions within their own database, the question becomes a matter of dispute resolution, as opposed to a lack of trust.
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.

@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.

“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.

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.
The consensus mechanism is centralized in the hands of a single entity which mission is to verify and add all transactions to the blockchain. A network based on a private blockchain, therefore does not need to use a mechanism such as “Proof of Work” or “Proof of Stake” which are complicated to implement and expensive. The problems of security being much more simple in the case of private blockchains, it is possible to apply the mechanisms of consensus lighter, more effective and therefore easy to deploy such that the BFT.
These kinds of blockchains are forks of the original implementations but deployed in a permissioned manner. Mainly hyped because the companies behind these chains want to onboard corporations in order to generate buzz around their their chain. It’s tolerable for proof of concepts or if they plan to move to public as soon as possible; otherwise they are just using the wrong set of tools for the job.
Sidechains are an essential innovation in the blockchain field with some interesting long-term implications and effects on the broader interoperability and scalability of blockchain networks. They are effectively extensions of existing blockchains that increase their functionality and allow for validation of data from other blockchains and for assets to be seamlessly transferred between them.
Hasta la fecha (Agosto del 2016), las sidechains sobre Bitcoin no son más que algo teórico. Una implementación de este tipo requeriría de un cambio en el código Bitcoin (hay miembros de la comunidad Bitcoin con gran prestigio, como es el caso de Peter Todd, que argumentan que una sidechain, tal y como la describe Blockstream en su paper, no podrían llevarse a la práctica en Bitcoin sin hacer un gran cambio, hard fork, en Bitcoin). En el mismo paper de blockstream se reconoce que una implementación de este tipo, la cual su teoría es simple pero su implementación compleja, se enfrenta a problemas que no está del todo claro que puedan solventarse (y no todos son de tipo técnico).
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.
At Iryo, we consider databases and blockchains that are not opened to the public to be insecure they, can easily be altered by the business running it, at their discretion and it goes against the ethos of the open and transparent cryptocurrency space. Designed to keep public out and introducing “trusted” middlemen, private chains forget that trusted third parties are security holes.
That is however not all. Sidechains also have some specific use cases, unique to a certain blockchain. One example is the usage of sidechains in EOS. EOS is currently facing a RAM problem. RAM is too expensive and developers are complaining. Sidechains could compete with the EOS mainchain by having lower RAM prices, this would lead to competition, incentivizing both the EOS mainchain block producers and sidechain block producers (mainchain and sidechains of EOS are maintained by the same group of block producers) to keep the RAM price as low as possible. This also means there is more RAM available, so the RAM price will go down as a result.
The words block and chain were used separately in Satoshi Nakamoto's original paper, but were eventually popularized as a single word, blockchain, by 2016. The term blockchain 2.0 refers to new applications of the distributed blockchain database, first emerging in 2014.[13] The Economist described one implementation of this second-generation programmable blockchain as coming with "a programming language that allows users to write more sophisticated smart contracts, thus creating invoices that pay themselves when a shipment arrives or share certificates which automatically send their owners dividends if profits reach a certain level."[1]
The public blockchain is open to anyone who wants to deploy smart contracts and have their executions performed by public mining nodes. Bitcoin is one of the largest public blockchain networks today. As such, there is limited privacy in the public blockchain. Mining nodes in the public blockchain requires a substantial amount of computational power to maintain the distributed ledger at a large scale. In the Ethereum public blockchain, smart contract codes can be viewed openly.
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.

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.
Instead, what if the game was played in its own “channel”? Each time a player made a move, the state of the game is signed by each player. After an epic battle where the Protoss player takes out the remaining Zerg forces and forces a gg, the final state of the game (Protoss wins) is sent to a smart contract on the main chain. This neutral smart contract, known as a Judge, waits a while to see if the Zerg player disputes the outcome. If the Zerg player doesn’t, the Protoss player is paid the 1 ETH.
Blockchain Council is an authoritative group of subject experts and enthusiasts who are evangelizing the Blockchain Research and Development, Use Cases and Products and Knowledge for the better world. Blockchain council creates an environment and raise awareness among businesses, enterprises, developers, and society by educating them in the Blockchain space. We are a private de-facto organization working individually and proliferating Blockchain technology globally.    
Saying that, Interoperability has been the missing link in conquering the obstacles faced by both private and public blockchains by empowering them to interact and exchange values across platforms seamlessly. Developers use of the Gallactic blockchain technology, that allow for private and public blockchains within its eco-system, will drive the potential to combine both public and private blockchains with innovative new solutions, designed to accomplish cross-chain exchange and greater compatibility is the way forward for all parties and their concerns.