– 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.
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.
Altcoin Altcoins Beginners Binance Binance Exchange Bitcoin Bitcoin cash Bitcoin Exchanges Bitcoin Wallet Address Bitcoin Wallets Bitfinex Blockchain BTC Buy bitcoins Changelly Coinomi Cryptocurrency Debit Card Decentralised exchange Desktop Wallet ERC20 ETH Ethereum Exchange Fork Hardware Wallet HD Wallets How to India Ledger Ledger Nano S Localbitcoins Mobile Wallet MyEtherWallet NEO Paper Wallet Privacy Private Key Review Security Trading Trezor Tutorial Wallet Web Wallet

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.
“Private blockchains are valuable to solve efficiency, security and fraud problems within traditional financial institutions, but only incrementally. Private blockchains will not revolutionize the financial system. Public blockchains, however, hold the potential to replace most functions of traditional financial institutions with software, fundamentally reshaping the way the financial system works.” 
Imagine there is a Bitcoin-like system out there that you’d like to use. Perhaps it’s litecoin or ethereum or perhaps it’s something brand new.   Maybe it has a faster block confirmation interval and a richer scripting language. It doesn’t matter.   The point is: you’d like to use it but would rather not have to go through the risk and effort of buying the native tokens for that platform. You have Bitcoins already. Why can’t you use them?
Ardor is a blockchain platform predicated on childchains (sidechains) that use proof of stake (PoS) consensus. It uses the primary chain as a security chain and the childchains for processing transactions to increase scalability. Their design is specifically focused on speed and efficiency through PoS consensus and removing blockchain bloat through pruning.
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.
If one group of nodes continues to use the old software while the other nodes use the new software, a split can occur. For example, Ethereum has hard-forked to "make whole" the investors in The DAO, which had been hacked by exploiting a vulnerability in its code.[31] In this case, the fork resulted in a split creating Ethereum and Ethereum Classic chains. In 2014 the Nxt community was asked to consider a hard fork that would have led to a rollback of the blockchain records to mitigate the effects of a theft of 50 million NXT from a major cryptocurrency exchange. The hard fork proposal was rejected, and some of the funds were recovered after negotiations and ransom payment.[32]
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.
So, there is a kind of centralized authority that decides who has a right to contribute to and to audit the network. What is more – it’s possible to restrict viewing information stored on private blockchains. It might seem that in such conditions, a blockchain is no longer the blockchain as it lacks transparency and decentralization. Well, these remarks are fair, but only when the network is estimated from the outside. Within it, the rules remain the same as for public networks: it is still transparent for all the members.
This is what, at its core, state channels are. Imagine we wanted to play a game of Starcraft and have a smart contract that pays 1 ETH to the winner. It would be ridiculous for each participant to have to write on the main Ethereum network each time a Zergling was killed by a Zealot, or when a Command Center was upgraded to an Orbital Command. The gas cost (Ethereum gas, not Starcraft gas) and time for each transaction would be prohibitive.

Start preparing for STO in a week with a professional blockchain development team. We have real experience in the following platforms: Ethereum, Stellar, Hyperledger, EOS We developed the world’s first platform for real business assets tokenization on Stellar that raised 1,700,000$ ! SheerChain is a custom software development company and a trusted IT outsourcing provider for our clients worldwide. Combinin ... Read more


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.
A company called Blockstream has been focusing on these developments and has announced the release of Sidechain Elements, which is an open-sourced framework for sidechain development. It includes a functioning code and a testing environment for working with sidechains with several components: the core network software to build an initial testing sidechain, eight new features not currently supported by bitcoin, a basic wallet and the code for moving coins between blockchains.
For example, let’s say we have side chain 1 (SC1) and side chain 2 (SC2). A transaction occurs on SC1. A node in SC1 broadcasts the transaction to nodes in the main chain to record this transaction. The same node of SC1 calls a function from SC2 with a proof. The function in the nodes of SC2 verifies the proof on the main chain. The function gets executed.
Smart contracts are immutable pieces of code and their outcomes are irreversible. Hence, formal verification of their code is very important before deploying them. It’s very hard to verify smart contracts in the Ethereum Virtual Machine (EVM). A business can’t afford to deploy faulty but immutable smart contracts and suffer the consequences of their irreversible outcome. This article details the challanges: “Fundamental challenges with public blockchains”.
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.
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?
“We believe that public blockchains with censorship resistance have the potential to disrupt society, when private blockchains are merely a cost-efficiency tool for banking back offices. One can measure its potential in trillions of dollars, the other in billions. But as they are totally orthogonal, both can coexist in the same time, and therefore there is no need to oppose them as we can often see it.” 
×