@gendal I am discussing private chains with prospects, so my interest is not superficial and theoretical. I see the benefits for the organization in using the private chain as another form of internal database, with better security properties. It can also be used where a service bus product would be today, to facilitate integration, conformance, monitoring, audit. Private chain can also, via a two way peg, be connected to the main chain, achieving a form of public/private network divide that routers created for us in the early stages of the Internet development. Anything else on the benefits side that I missed?
This is justified by observing that, in our pre-sidechain world, miners always want things to be correct. In theory, the incentives of miners and investors are very strongly aligned: both are compensated most when the exchange rate is highest. And, in practice, we do not see large reorganizations (where miners can “steal”, by first depositing BTC to major exchanges, then selling that BTC for fiat (which they withdraw), and finally rewriting the last 3 or 4 days of chain history, to un-confirm the original deposits). These reorgs would devastate the exchange rate, as they would cast doubt on the entire Bitcoin experiment. The thesis of Drivechain is that sidechain-theft would also devastate the exchange rate, as it would cast doubt on the entire sidechain experiment (which would itself cast doubt on the Bitcoin experiment, given the anti-competitive power of sidechains).
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.
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." 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, 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." 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."
The ethereum-based app builder has a dedicated team of experts looking at all varieties of fiat cash on distributed ledgers, and it's working with UnionBank of the Philippines to create a low-cost tokenized fiat solution for rural banking. In time, this could be extended to cover a larger network of banks and perhaps even the central bank, ConsenSys says.
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.
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.
Bitcoin and other cryptocurrencies currently secure their blockchain by requiring new entries to include a proof of work. To prolong the blockchain, bitcoin uses Hashcash puzzles. While Hashcash was designed in 1997 by Adam Back, the original idea was first proposed by Cynthia Dwork and Moni Naor and Eli Ponyatovski in their 1992 paper "Pricing via Processing or Combatting Junk Mail".
Blockchains that are private or permissioned work similarly to public blockchains but with access controls that restrict those that can join the network, meaning it operates like a centralised database system of today that limits access to certain users. Private Blockchains have one or multiple entities that control the network, leading to the reliance on third-parties to transact. A well-known example would be Hyperledger.