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November 26, 2015, 03:46:23 PM |
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article written on quora by NotsoFast Crypto. link:https://www.quora.com/Bitcoin/What-is-the-fastest-blockchain/answer/Notsofast-Crypto
The fastest blockchains, which offer confirmed and re-spendable transactions in 1-5 seconds, are:
DASH using its InstantX protocol, which uses somewhat centralized Masternodes to "pre-confirm" a transaction;
VanillaCoin using its ZeroTime protocol, which uses a secondary process on the whole VNL network to "pre-confirm" a transaction, unless that transaction is attacked, in which case it is verified and resolved normally.
When referencing the speed of a blockchain, we're almost always talking about the time it takes for the blockchain's miners to find, process, and distribute the next block in the chain. Most blockchains are built with a target spacing between blocks, so that even if there's a shock to the network-- such as a major internet outage forcing many mining nodes offline, or a massive amount of new mining power suddenly jumping on the network-- there's a hard-coded mechanism to preserve the regularity of block issue.
But for practical uses, target spacing isn't enough. You need to know your transaction is confirmed multiple times over in order to reduce to virtual impossibility the chance that a bad actor could attack the network and revise the current consensus blockchain to his benefit. This is why the Bitcoin blockchain recommends at least two, and as many as six, confirmations on a transaction, meaning your transaction is two to six blocks deep in the immutable transaction record: it gets exponentially harder and more expensive to attack each older block. After six confirmed blocks in the Bitcoin network, the integrity of your transaction is guaranteed.
We use many soft solutions to speed this up. Some third parties, like Coinbase, will reduce the amount of confirmations they require from six in order to allow you to spend or send a small amount of bitcoin more quickly. They do so at acceptable risk to their own reserves: if somehow those smaller transactions are successfully attacked, it's a trivial matter to reimburse their users. However, soft solutions only speed up the network in certain practical cases, by accepting additional risk. They don't fundamentally improve the speed of any given blockchain.
But developers have been working on improving on blockchain technology to fundamentally increase the speed of guaranteed transactions. So to finally answer the question of which blockchain is the fastest, let's look at two cryptocurrencies which have implemented technology bringing practical, unassailably confirmed, re-spendable transaction times to between 1 and 5 seconds.
DASH InstantX technology (InstantX)
The whitepaper linked above shows how DASH (formerly Darkcoin) achieves fully confirmed transactions in a few seconds using its InstantX protocol.
InstantX is achieved using two DASH innovations: a special network of higher-order nodes called Masternodes, and an additional decentralized function of those nodes called transaction locking.
A Masternode (MN) is incentivized both with collateral and additional shares in every proof-of-work reward: a DASH MN must put up 1000 DASH as collateral and securely host its MN software. In return each MN receives an equal share of 20% of every proof-of-work block, no matter who mined it. MNs perform additional functions within the DASH network, one of which is transaction locking.
Briefly, transaction locking allows a pesudorandom subset of deterministically elected masternodes to very quickly form a proxy "early consensus" on a transaction even before the normal proof-of-work consensus verifies it in the next block. Any attack on this consensus (by trying to send those same DASH to a different address in a double-spend attempt) is rejected by the MN network until proof-of-work verifies everything. The end result: an almost instantaneous, fully-confirmed, fully-guaranteed transaction of DASH.
(See the above whitepaper for a more detailed description of the InstantX process, and an account of how it's safe from standard attacks on a blockchain.)
It's important to note that the number of MNs must remain high and distributed in order to prevent collusion attacks on the DASH network. Since MNs are a form of centralization-- not unlike major Bitcoin mining pools-- all services deriving from the MN protocol aren't considered to be the final improvement on instant transactions within a decentralized blockchain network.
VanillaCoin ZeroTime protocol (Page on vanillacoin.net)
The above whitepaper shows how VanillaCoin (VNL) achieves near-instantaneous, fully-confirmed transactions using its ZeroTime protocol. VanillaCoin's developer specifically references DASH's InstantX at the beginning of his whitepaper, citing the specific improvements he's made over InstantX to achieve this transaction speed on the fully decentralized VNL network.
The ZeroTime protocol is similar in some ways to InstantX in that it uses a secondary process within the existing network to achieve consensus on a transaction by locking it, rejecting conflicting transactions prior to actual blockchain confirmation, then releasing the lock. Though this process is more complex than a regular speed transaction, it's completed in 372 milliseconds. ZeroTime's main mechanism for protecting against attacks is to simply cancel out conflicting transactions for inclusion in the next regular proof-of-work or proof-of-stake block: an attack or attempted double-spend will at best only ever succeed in slowing a ZeroTime transaction down to the next issue of a VNL proof-of-work or proof-of-stake block.
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