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Alternate cryptocurrencies / Announcements (Altcoins) / Re: [ANN][Qtum] Testnet June| A Scalable POS Smart Contract Platform| $15.6M raised
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on: May 15, 2017, 03:22:51 AM
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just want to know the classic proof of stake consensus has a lot of problem
how do you solve it in Qtum ?
thank you
"
POS Attack Vectors
the main attack vectors to the consensus approaches analyzed later in this section are summarized. In general, Denial of Service (DoS) and Sybil attacks against these approaches (performed at the network and/or consensus protocol levels) are possible. A DoS attack is an explicit attempt to disrupt the normal operation of the blockchain network by sending lots of data to its nodes (for example, by sending many transactions of low value so the system cannot process normal transactions). In a Sybil attack the normal operation of the network is subverted by a malicious adversary that creates and controls a many misbehaving nodes (which could appear as belonging to different participants).
Miners' default behaviour in PoW consensus is to immediately announce to the network each new found block. In selfish mining attacks, a misbehaving miner attempts to waste computational resources of other miners, as follows. When the malicious miner finds a valid block he temporarily withholds it and continues mining on top of it, trying to find more blocks before the other miners even find one; and when another miner finds a valid block, the attacker announces the blocks he was withholding. Even if for some researches , this attack vector could be in practice very unlikely, as mentioned in section IV.D, there are cases where miners could be motivated to carry out a slight variant of this attack, where valid blocks are selectively discarded in order to modify the result of a stochastic procedure in which there is much at stake.
In a short-range attack the attacker, controlling certain percentage of the resources used to secure the system (e.g., computational resources or cryptocurrency stake) performs a transaction (e.g., to spend coins or to execute a step of a contract) and then tries to reverse it (e.g., to make a double-spending, that is, successfully spending some of the cryptocurrency coins more than once) as follows. After the attacker submits to the network the transaction he aims to revert, he starts mining a blockchain fork (from the previous block) in which that transaction is not included, without publishing it until that transaction has at least a certain number n of confirmations. If by then the attacker achieved to mine (mint) more than n blocks in his blockchain fork, he publishes it, and being this the longest chain it is accepted as the new valid blockchain by the network; therefore, the transaction in question is reversed.
In a long-range attack the attacker (controlling a certain percentage of the resources used to secure the system) starts mining a blockchain fork from many blocks back or even from the very first (genesis) block; aiming to obtain block rewards and/or to reverse a transaction. This attack would be possible in systems based on PoS consensus, given that although the attacker may only own a small percentage of all coins (at the point of the fork), in his blockchain fork he is able to move his coins freely, which allows him to solve the computational puzzle to mint blocks much more easily, and therefore, to rapidly build a longer blockchain.
A coin-age accumulation attack could be possible in approaches based on PoS where the coin-age is used to compute a measure of nodes' stakes, the total
consumed coin-age determines the valid blockchain, and the coin-age of an unspent transaction output (UTXO) is computed as its value multiplied by the number of blocks elapsed since it was created (e.g., Peercoin as will be seen later in this section). In this case, the attacker would split the coins he owns (a high enough percentage of all coins) into multiple UTXOs and wait until his stake becomes several times the average. Then, after that, the attacker would be able to mint several blocks in a row with a high probability, allowing him to fork the blockchain and reverse transactions (e.g., to make a double-spending).
In PoS consensus the solution to the puzzle necessary to mint a given block depends on the previous block's hash. Then, an attacker (with enough computation resources and stake) minting at height h of the blockchain could try to influence the hash of the current block (by selectively modifying its set of transactions) in a trial and error process until he is able to mint the block at height h+1. This is known as a pre-computation-attack and it could be done recursively in order to build several blocks in a row, to obtain the corresponding block rewards and/or perform a double-spend attack.
"
also Ethereum seems will not switch to fully POS until 2018 or 2019 ?
and their Casper is not ready yet,
why Qtum choose POS from the very beginning?
thank you!
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206
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Alternate cryptocurrencies / Announcements (Altcoins) / Re: [ANN][Qtum] A Scalable POS Smart Contract Platform| 11156BTC+77081 ETH raised
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on: May 12, 2017, 04:08:52 AM
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Update:Skycoin is finally getting an order book. This took too long. - next exchange upgrade/rewrite skycoin will float against bitcoin The blog is going to be ready tomorrow and we will start migrating content. We are going to announce several partnerships with large mainstream institutions, so have to cleanup a bunch of stuff and will migrate anything relevant to blog. We will put a lot of content on the blog and things we have not revealed yet.- information about coin distribution plans and any loose ends will go on the blog - for the blog we are using hugo for the blog, which takes flat files in markup and generates static html files. So will work over IPFS and eventually CXO. We are doing rewrite and improving the narrative on - http://skycoin.net- it will be easier for people to take a simple message away from the website about long term project goals, what is skycoin, etc - we will test out a new, simpler narrative and see how people react. We will deemphasize the software aspects and infrastructure We need to get the first application for the platform/ecosystem on the website. The blockchain explorer is up at - http://explorer.skycoin.netWe are doing the third generation skycoin wallet and completely redoing the wallet frontend and design, to start multicoin support (for Skycoin, Bitcoin, Ethereum and Qtum). The new wallet will be based upon the design of the Byteballs wallet. We are getting more developers and focusing on improved project management process and expanding the development team further. The CXO standard for immutable data objects and CXO daemon is almost done - http://github.com/skycoin/cxo- Skycoin block and transactions will eventually be stored, synchronized and exchanged over the network as CXO objects. The skycoin blockheaders and the transaction list in the Skycoin blocks will be stored as separate objects, to allow headers first download. Congestion control on the meshnet is done. We have ~4 tickets left before will have something working. It works very well at 2 MB/s per core but needs optimization and there are still bottlenecks in the congestion control. We have a skycoin introduction video in production now. We need to find a good narrative and message. Development Chat:http://skycoin.chatWe have a mattermost server now. Byteballs and Qtum Crowdsales:These are very interesting. Everyone should look at these - http://byteball.org/- https://qtum.orgQtum, will probably replace ethereum because it is simpler and has fewer problems. The UXTO model is much cleaner. They have a lot of previous developers and have already done two previous coins and are the best team I have seen so far.Byteballs is the first coin (besides skycoin) to be able to achieve consensus in a public network, without mining. They have gotten rid of the blockchain and replaced it with a DAG. I think the future is going to be with a variant of this approach. We have been considering this for years, for a Skycoin 2.0. I have not reviewed their code or implementation, but the concept is extremely innovative.
From the skycoin developer: Qtum, will probably replace ethereum because it is simpler and has fewer problems. The UXTO model is much cleaner. They have a lot of previous developers and have already done two previous coins and are the best team I have seen so far.What's the benifit of UTXO based smart contact platform when you compare with Ethereum, Since Ethereum is using account model? from my understanding account model is more easier to build smart contact? while utxo model can parallel process the transactions? thank you |
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Alternate cryptocurrencies / Announcements (Altcoins) / Re: [ANN][XEL] Elastic Project - The Decentralized Supercomputer
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on: May 10, 2017, 03:25:00 PM
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We were on a roll, the impatience of some has pissed of the devs. Yes the alts are on the rise, but it could be a bubble. This isn't a pump and dump project. Look at Decent, all the fud they get and they won't launch until "THEY" say they're ready. So if EK states that the project is not ready for launch, we should listen. He's trying to do something unprecedented in the crypto space.  you have a point, but i think it's still good if people can vote. |
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Alternate cryptocurrencies / Announcements (Altcoins) / Re: [ANN][XEL] Elastic Project - The Decentralized Supercomputer
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on: May 10, 2017, 02:13:28 AM
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SOMN (which the article is about) sounds really interesting. They've done their site out to show the use cases that SOMN will be used for: Essential scientific calculations which constantly require massive computing power are easily run on SONM – social statistics – climate predictions – bioinformatics – aerodynamic calculations – drug development – modeling – meteors trajectory modelling And that's just one small part of it. They talk about deploying game servers, neural network projects. They've certainly got their PR together. All they have is PR. I want to come up with my own coin that will cure cancer, ED, baldness while can be used for any type of gaming. I don't know how, but that's not important. The main thing is PR  That's why you need good PR. They've already had a pre-ICO that sold out and it looks like their ICO will sell out as well. That's the power of good PR. thats the power of scam coins....pre-ico and second ico  def scam Can we have some update on our project Elastic ?
It's basically quite simple: - We will have a voting. - We will have the options: :Lite-Wallet with basic coin transfer functions :Wait for Full-Wallet And eventually a third option which would mean: :Minimum-Viable-Product-Option But regarding the last option it's still undecided if doable and supported by EK. Thank you for the info. Simple and informative as always ! wait for full wallet! Software Development looks like a life cycle. There is no best time. Look like to bitcoin, we are still using bitcoin with 0.X version. It is still experimantal, nobody think about that, but bitcoin is not version 1.0 yet. Did i explain? So we can use too lite wallet for contribute to Community. We are behind of the door, we need to reach more people.. lets start to vote for lite wallet & mainnet you have a good point. i think we need to release the lite wallet first. |
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Alternate cryptocurrencies / Announcements (Altcoins) / Re: [ANN][Qtum] A Scalable POS Smart Contract Platform| 11156BTC+77081 ETH raised
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on: May 08, 2017, 02:23:09 PM
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This will be a good opportunity for chinese investors but for the westerners i think you need to hold on to your saddles before jumping in. it has a good potential to be big, the transparency issue is still at question, numbers with signature in it can only prove so little.
how much transparency you get from ETH? and also from satoshi? it's a bubble time now.  only things matter right now, i hope Qtum get 100k people in their community in china. then i will buy a lot. I know your a Qtum fanatic and The ETH address presented is still not clear if it is from the Qtum ICO, back read a little pages. and the one asking how many chinese pump the token. Not so many it was over inflated token. that is why its too risky to buy it when it hit the exchange majority of the token is on the chinese hands and they are waiting to dump it to unsuspecting westerners. i think these Chinese people will pump it like Ethereum.  why you worry about this? |
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Alternate cryptocurrencies / Announcements (Altcoins) / Re: [ANN][XEL] Elastic Project - The Decentralized Supercomputer
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on: May 08, 2017, 09:05:50 AM
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Making the launch before we even have a stable MVP with important working functionalities this project is aiming for is a HUGE mistake.
It does not have to be 100% perfect with all the future functionalities we wish to have for the system (perhaps that would be utopia), BUT, it needs to have enough meat to be worth something substantial when entering the market.
Elastic is not the first to reach the market (other projects are there before us), it has no deep pockets as some projects have after raising millions in the ico (we need to open a foundation and collect some donations for this), the ONLY thing that we can have as an advantage today is to release something that actually works (even if it has only some of the functions working at launch) - a lite wallet will completely miss this point.
And again, after we have such product to launch we need to have a ready website with minimal info (what we have is not even close to being good enough).
I understand that some of the people who invested want to join the boiling market to take a piece of that huge pie, but we need to stay patient enough to do this smart, otherwise we will be flushing this amazing project to the drains.
Give EK the credit he deserves - he delivered so much so far, let him take us to the point where we can launch it well with at least some of the needed features with a stable system - I can promise you all that this will draw much more positive attention also to future devs to join.
(side note: for those who prefer to make a fast launch of a coin with no functionality so they can buy cheap coins before the system can gain greater value - don't cripple this project for your own wishes for personal gains).
let people vote for this? |
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Alternate cryptocurrencies / Announcements (Altcoins) / Re: [ANN][Qtum] A Scalable POS Smart Contract Platform| 11156BTC+77081 ETH raised
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on: May 08, 2017, 09:03:00 AM
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from Qtum news letter :
Qtum Development Updates
Changes made through this week to the core wallet:
Bugs fixed:
* [Misc] Fixed a bug where Qtum would fail in some cases on OSX
* [RPC] Fixed a potential upstream bug where decodescript would sometimes cause a segfault and crash
* [Consensus/EVM] Fixed a bug where some EVM fields in the block header were not fully validated
Work completed:
* [Testing/RPC] Added automated tests for contract related RPC calls
* [Wallet/PoS] Added automatic PoS staking support
* [Wallet/PoS] Added "reserve balance" support, to opt-out a set amount of coins from being staked
* [Wallet/GUI] Added staking information to the Qt GUI
* [Testing/AAL] Added automated tests to verify the logic and edge cases for condensing transactions in the AAL
* [Testing/Misc] Changed Python QA tests to support new block header changes
* [Wallet/PoW] Added automatic PoW mining support (to be used only initially before release)
Ongoing in-progress work:
* [Consensus/EVM] Fixing a bug where a transaction could enter an out of gas state due to other gas consuming transactions in the block
Design work:
* [Consensus] Primary design work complete, initial implementation has begun. More details will be released later in a long-form article or blog post
* [Consensus/PoS] Secondary design work mostly complete. More details will be released later in a long-form article or blog post
Brett Fincaryk, the Community Manager for the Qtum Foundation, spoke at Mexico's local blockchain meetup educating the community about the Qtum project and our progress so far.
Join the Qtum Forum
We launched the Qtum forum where we will publish official Qtum updates and engage with the community. The Dev Team will be taking part; so, you can ask questions about how you can get started developing on Qtum once the testnet is live.
JOIN NOW
Recent News
Patrick Dai, co-founder of the Qtum Project, was recently recognized as a Fellow of Singapore University of Social Sciences for his expertise and experience in blockchain technology. We are happy that Patrick is a part of our team and proud of this recent accomplishment.
-Qtum
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