Topic: [ANN] (QTUM) - A Scalable Smart Contract Platform w/ Proof of Stake - page 157. (Read 525459 times)

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!

thank you for the updates.

looking forward to the testnet release.

hope the testnet will release in june!

then we can test the first UTXO based smart contact platform!

this will be big for sure.

First UTXO based smart contact platform
First POS smart contact platform.

Looks like it's a good coin ....
I was very impressed after reading some of their articles. Waiting for more news. Good luck

The Main Network will be released in September, but the Test Network is due for June. What's important is stability testing of the test network, we're giving ourselves 3 months to make sure there's no issues.

yea, I think you have enough sent your thought to investors about the matters.
I understand your thoughts but I don't think he's representing all the team.
If it is not difficult, you'd better sue him
Each member of the team is an important people of the family like you.
And now It is an important time to prepare for the future. So do you, too.
If you have nothing to say, I wish you would stop it. Thank you.

I've got nothing else to say, thanks. Just direct any questions elsewhere because I don't check this thread. This is the first time in probably months.

I know what you're talking about. It is the end that you want say? or what is you want? I think you don't have anything else to say here.

Yes he did, he partnered with Bobsurplus secretly and they even used the "Bay west toilet paper logo" from day one to mock me and they used fake profiles to discredit and harm my rep. I got sent pdfs in secret(they had a mole in the group), was shown fake profiles that got hacked by some people proving the propaganda campaign. It was seriously a rabbit hole. To this day, it still kind of humbles me. Their modus operandi was similar to JTRIG. Man, to be honest I don't mean to bring up the past but its true(I don't live in the past, every once in a while I'm candid). I don't think buying into your ICO is illegal per se but the website they set up was wrong because they lied about the funds release schedule and mocked me knowing that when I said something the project would crash. So that would constitute as fraud but extremely hard to prosecute. To add insult to injury, Bob would come by every few months to make fun of the investors he stole from. So Dai is lower than dirt to me. I tried to pursuade him to help and he was very blahzay and eventually just ignored me even when I tried to be NICE when it was eating me inside. I'm certain Qtum was pumped. Knowing that last time Dai partnered with Chinese exchanges like BTER who stole funds from users on so many occasions(millions they still owe me almost 3 btc). Qtum funded in "90 minutes" what does that tell you? Lol... and that was while Gleb was bombarding this thread. No way they funded what they claimed unless his rich chinese friends wanted free coins or something. Same Modus Operandi with just bigger numbers.

We all think Dai sold his Bitbay because he admitted it on the slack when I confronted him saying it "wasn't worth anything". But it was worth something to investors who didn't want to be dumped on. It shows how much contempt this dude had for us(he certainly didn't tell me while he was dumping). If you ask Dai directly I doubt he will give you a straight answer that is cogent.


Ironically, I'm not saying Qtum won't be a success. They very well may put contracts in UTXO which is in fact a better way to do it. I've often chastised Ethereum for bloating up the blockchain and it is true in fact, I think I might have even talked to Dai about this idea in the past that it is cleaner to do it that way. You just pay a hash, send a payload and sandbox it. It's not actually that hard. Ethereum is over-engineered in my opinion and will have 10x the scaling issue as Bitcoin or even Qtum and to be honest Ethereum is much more greedy and potentially have back door deals that would shock us.

I'm not here to take away from anyone's efforts, I've got better things to do like CODE. But let investors never forget this guy did leave with investors funds that he didn't work for, dumped his coins etc. There is NO FREE LUNCH in life. God knows how many times some CEO bankrupts his own business keeps investors funds and never sees bars (possibly Trump for example? haha). White collar crime isn't taken seriously which is why everyone wants to destroy wall street. Sadly, if investors don't get smarter, the process will repeat itself. So take this text for what its worth. BitBay has made tremendous progress and of course the peg will finish.

But maybe the guy is right, investors don't care who this guy is, they just want to make money. Still, I would never invest regardless even if they crapped gold bars. But thats my personal opinion perhaps many investors simply don't care. The ones that do, will listen carefully.

Newsletter Update:







Qtum Development Updates


Changes made through this week to the core wallet:

Bugs fixed:

* [Wallet] Fixed a bug where sendtocontract and sendtoaddress did not track their inputs properly and could try to spend already spent inputs.
* [Consensus/EVM] Fixed a bug where the vin SigScript would sometimes be empty for an AAL created gas refund

Work completed:

* [Consensus/PoS] Added Coinbase and Coinstake rules for PoS
* [Wallet/PoS] Added internal block creation for PoS that properly handles new EVM block header fields
* [Testing/EVM] Added more automated tests for new EVM block header fields
* [Consensus/EVM] Changed the method used to validate AAL created transactions to ensure that their order in the block and exact values are all consensus-critical
* [Consensus/PoS] Added most of the PoSv3 base consensus rules from validation.cpp

Ongoing in-progress work:

* [Consensus/PoS] Working on adding the remaining PoSv3 consensus rules from net_processing.cpp
* [Consensus] Working on initial DGP framework implementation



Community







Xiaolong, Patrick, and John educated students at Fudan's MBA Blockchain Association event this past Wednesday. At this event, the Qtum team introduced students to Bitcoin, its history, and economic incentives.








In addition, Patrick and John lectured master's and undergraduate students earlier that Wednesday on blockchain technology and Qtum in an International Finance class at Fudan University.



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.


https://forum.qtum.org/



Recent News:









"Another example of China’s unique take on the blockchain resulting in interesting technological vectors is the Qtum project. Qtum, pronounced "Quantum", is a turing-complete smart contract blockchain, combining its own version of the Ethereum Virtual Machine with a Bitcoin blockchain. The result is a blockchain stack, able to execute ethereum-like smart contracts in mobile environments such as Smartphones, Tablets and IoT devices, which the company’s leadership recognized as the most necessary feature for corporate and government blockchain adoption.

Furthermore, Qtum plans to incorporate a smart contract template hub in its service, which will make it easy to write financial applications which adhere to commercial rules and regulations and which utilize digital identities."

No point in arguing with him man, his mind is made up as he is set on protecting his little 900 qtum investment and is ignorant of anything else.  It's obvious to anyone with a brain that you're more knowledgeable in this space than he will ever be.  I bought some tokens in the qtum ICO on a whim, without looking too deep in the Bitbay thing.  Had I known, I probably would have reconsidered. 

Would you say that Dai created the Bitpay project originally with the intention to scam though? It seems to me that this was a case of an arrangement gone bad, and Dai grabbing whatever he could get his hands on (regardless of whether he was entitled to it) and running for the door when he realized that the building was on fire.  Pumping the ICO reimbursing himself is shady as hell, but with the lack of regulation in the crypto market was it legally wrong?  Technically ICO funds are supposed to be at the disposal of the founding team, and he is apart of that team.  In any case i'm not sure that Qtum was even pumped.  The speed at which they raised the funds looked shady at first, but when you consider that TKN ICOd after and raised the same amount of money in under 30 minutes, then they could have easily reached 15m without any pump.  I think it's more of a sign that we're entering a bubble and people are eager to throw $ around.

I feel for what happened to you man.  You got put in a crappy situation by some shitty individuals who took advantage of your good nature and talent.  It looks like you've put in an incredible amount of work as the solo developer and I hope your project pans out to be a great success.  It sucks though if Dai still holds 10% of all bay like you say then him profiting off your blood & sweat is definitely a double edge sword. 

New article mentioning the Qtum project at TheVerge


















By tanvirzafar  on May 11, 2017 07:14 am 
 


For Western audiences, especially crypto enthusiasts, China and the Blockchain may seem like slightly strange bedfellows. Thinking about anonymous Bitcoin hero, Satoshi Nakamoto and his colorfully diverse followership, the People’s Republic’s central planners are not the first to come to one's mind. In light of this, Beijing’s decision from earlier this year to include Blockchain technologies in the Communist Government’s upcoming 5 year plan, might have struck many as surreal.

On the ground however, the numbers tell a much less ambiguous story. With $10 Billion flooding the country’s fintech sector alone, China moved in 2016 to the third place globally in Blockchain investments. The PBC, China’s Central Bank, is actively endorsing this tendency and is investing "significant resources" in the technology while encouraging the Republic’s financial sector to investigate blockchains with the goal of increasing transparency and countering fraud.

Better known for their tendency towards pragmatism and efficiency than for their love for decentralization and libertarian ideals, China’s economic stewardship has reasons of its own to pursue a leading role in the crypto industry. Namely, China simply believes that blockchains are a reasonable method to digitize trade. This cautious and down-to-earth attitude of the country’s leadership seems to have its impact on the local entrepreneurial scene. Leading Chinese blockchain projects put much less emphasis on the somewhat revolutionary rhetoric we are used to from their Western colleagues, and don’t shy away from making their platforms suitable for a world in which government regulations and know-your-customer rules are a given fact.

One company, Metaverse, has made this Zeitgeist into its official mission statement. Proposing a blockchain environment in which people, organizations, and governments can transact with each other, using digital identities and verifying agents, Metaverse chooses a tone very different from most projects of its kind.

In an interview from late 2016, the company’s CEO and founder, Eric GU, stated that "at Metaverse, we don’t believe that the blockchain will get rid of middlemen. [...] Ultimately, we should respect them. Many blockchain projects want to get rid of middlemen. Metaverse celebrates them, governments, organizations, people, professionals. They have a critical role to play in identity and reputation."

While western projects struggle to make peace between their adherence to absolute decentralization and anonymity and the need to interface with a global economy, requiring regulatory checks and balances, their Chinese competitors are much more interested in making the blockchain business ready as soon as possible. This attitude, albeit less trendy among the community followership, has recently generated a great deal of interest among global institutional investors and very often dictates the problems these teams try to solve.

The Antshares project’s goal, for example, is to allow for the digitalization of real-world financial assets, such as shares and securities. The idea behind Antshares is not to create yet another crypto market for tokens, essentially devoid of any real-world backing, but rather to create a cryptographic platform on which shares, bonds and other highly regulated securities, backed by corporate profits and liabilities, can be traded.

This, very often, also has technological implications. Antshares chose the dBFT consensus mechanism for its blockchain, making it so that the system is secured against potential forking events and allows for transaction volumes comparable to those of centralized clearing systems such as Visa and the like - A choice until now made only by highly institutionalized western projects such as hyperledger.

Another example of China’s unique take on the blockchain resulting in interesting technological vectors is the Qtum project. Qtum, pronounced "Quantum", is a turing-complete smart contract blockchain, combining its own version of the Ethereum Virtual Machine with a Bitcoin blockchain. The result is a blockchain stack, able to execute ethereum-like smart contracts in mobile environments such as Smartphones, Tablets and IoT devices, which the company’s leadership recognized as the most necessary feature for corporate and government blockchain adoption.

Furthermore, Qtum plans to incorporate a smart contract template hub in its service, which will make it easy to write financial applications which adhere to commercial rules and regulations and which utilize digital identities.

In the light of this, the People’s Bank of China Vice Governor Fan Yifei’s statement, urging central banks across the globe to "lead on digital currency development", should come as no surprise. "The conditions are ripe for digital currencies" Fan wrote in a guest article for Bloomberg, claiming that cryptocurrencies "can reduce operating costs, increase efficiency and enable a wide range of new applications."

In his article, Fan also claimed that government regulation can remedy many of the current shortcomings of cryptocurrencies, such as unstable value, weak credibility and lack of acceptance. A cryptographic legal tender, argues Fan, holds the potential of combining the advantages of current and alternative currency systems.

If this attitude will remain in place, would the dynamics of decentralized crypto-markets conflict with the PRC’s view of things, remains to be shown. With this kind of institutional backing, however, China will be, and already is, a safe haven for many blockchain projects escaping the saturated western markets.

Right! I think there are guys nothing to do . haha, No one interests in them

But Qtum team have always proved worth throughout Dev work, PwC, Whitepaper, etc

I look forward to the future of Qtum

Unfortunately, ICO is over and we can buy Qtum in September in Crypto exchanges
 
https://qtumnexus.slack.com/  This is Qtum slack channel

Good luck to you

Qtum will be one of the most biggest cryto in the world !

What? That is total nonsense. My software I've been working in for 3+ years, it's over 50000 lines of totally original code, is still the only software in the world with a full UI for smart contracts and of course it works. Have you ever even downloaded it!? It has a free coin faucet you can take. It's got 100s of little features. Of course it works! When is the last time you tested it 2 years ago?! Lmao. You realize I'm the only.coder? I would like to see you make something like this.  Seeing is believing watch it being used on YouTube

BitBay Tutorials: http://www.youtube.com/playlist?list=PLILfNPSQCo6yjFiwXY6-C-ikIDs6v2nHU

And of course I'm adding the rolling peg. Everything I say I'm gonna do I always do. That's why we have decentralized markets and they have been working for almost 2 years. I code until my fingers are sore. Unbelievable nonsense. I know exactly how to implement it I just want to finish the other templates first so there is nothing left to do on the roadmap. That's the whole point why it's so fucked up that Dai and Bob tried to hurt my rep, they steal money off my name and then leave the project. If you put yourself in my shoes you wouldn't even have been able to handle it.

From where to buy qtum .... ?
And what is the price ?..
Is their any slack channel ?

seems Qtum start to response your questions man, check it





but also i still want to know about the development work.

i think later, when Qtum release the testnet people will start to troll Qtum copy bitcoin and Ethereum. 

This is crypto! Most people here know the risks and don't need your 'friendly' warnings thank you.

i think you have a good point.

let's expect all the trolls come back soon and welcome them.

people will start troll Qtum again, Since Qtum will release testnet in june.

be ready for this! 

i think people in china know this, but they do not care.
why people care who is satoshi?
people only care the software, and people in china think you are scammer,
because you promised peg in bitbay, but you never finish it and it's not working.
also i think if you have any ideas or opinions, you can post on bitbay thread.