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AMA Recap of CEO and Co-founder of Chromia, Henrik Hjelte in the @binancenigeria Telegram group on 03/05/2020.

Moh (Binance Angel)🇳🇬,
Please join me to welcome, “CHROMIA CEO & Co-founder, Henrik Hjelte” and “ CMO, Serge lubkin”
Oh, before we proceed, kindly introduce yourselves and tell us a bit about your roles at Chromia u/sergelubkin & u/henrik_hjelte.
Henrik Hjelte,
Ok, I’m Henrik, I’m CEO of ChromaWay that crated the Chromia project. My background is a bit mixed: developer for 30+ years (since 80: s), but I studied other things at university (economics, politics, social sciences philosophy). Life is more than computer you know… I worked with FInance/IT then started a web startup and got to know Alex Mizrahi who worked as a developer….
Web startup didn’t fly, but Alex showed me bitcoin. When I finally read the whitepaper I was blown away, and joined Alex colored-coins project, the first open source protocol to issue tokens. in 2013.
So, we started with open-source tokens (that kickstarted the blockchain industry. Then started company together 2014.
That is a long intro, I’ll shut up now… Thanks….
Serge,
I’m Serge, I’m assisting Henrik today and I work with Chromia marketing team as well as on some business development projects
Moh (Binance Angel)🇳🇬, , Question No 1 :
Kindly describe the CHROMIA project and what it aims to achieve?
Henrik Hjelte,
Chromia is a new public blockchain based on the idea of integrating traditional databases, Relational databases with blockchain security. Chromia is a general purpose blockchain with full smart contract capabilities, just that it is a lot easier to code, even complex applications. You code with an easy to learn new programming language that combines the power of SQL and normal languages but makes it secure in a blockchain context. Up to 1/10 the code-lines vs other blockchains. There is a blog post about it, I’ll share later. On lines of code.
The aim of Chromia is to combine relational databases, which exist in every kind of organization, together using blockchains. We want to provide a platform for our users to develop totally decentralized apps securely. Our goal is for Chromia to be seen as the number one infrastructure for decentralized applications.
https://blog.chromia.com/reasons-for-rell-compactness/
Moh (Binance Angel)🇳🇬,Question No 2:
What inspired the CHROMIA Core team to pick interest in CHROMIA project? what breakthrough have you achieved so far? what are the present challenges you’re facing and how are you planning to overcome them?
Henrik Hjelte,
We started with public blockchains, tokens in 2012, the world’s first stable coin with a bank 2015 (LHV). When coding that solution, peer to peer payments of Euro-tokens, we discovered we need performance reasons to store all data in a database. We needed to quickly know the “balance” of a user, and can’t loop through a blockchain. And slowly the idea grew that we can make the database INTO a blockchain, integrate completely with the transaction mechanism of a database. So, we did it as a private blockchain first (Postchain), used it for some projects, then came up with the idea to make a Public Blockchain based on it.
The motivation is that we felt we needed a better programming model for blockchains. Our CTO Alex has always been thinking of optimal solutions for blockchain technology and has lots of experiences thinking about it. Also: make real-world useful things. For example, we support free-to-play models since users do not need to own “our” token to USE apps, the application itself (often the developer) pays for hosting. And of course, great performance. Also: more knowledge of who runs nodes and risk level. So, it is more suitable for enterprises.
In Chromia the application (at the start the developer) decides Who should be allowed to run its own blockchain (every dapp has its own blockchain). You can also say on a higher level that we want to provide technology to create “Public applications”, a tool
that enables us to create a fairer world.
https://blog.chromia.com/towards-publicly-hosted-applications/
Moh (Binance Angel)🇳🇬, Question No 3 :
Why did you create your own blockchain instead of leveraging on existing and proven base layer protocol?
Henrik Hjelte,
None of the existing protocols are suitable to support large-scale, mainstream applications. We designed Chromia to give our users exactly what they want; fast support, useful features, with an affordable service cost. Other platforms do not have the ability to host data applications in a decentralized and secure way, as Chromia can. Chromia also has its own bespoke programming language that sets it apart from SQL-based platforms. It’s so easy to use, even non-developers can understand it!
The other big difference with Chromia concerns payments. Chromia gives its users freedom from having to pay for each transaction. With Chromia, you have the flexibility to decide how to set fees for your dapp
And when it comes to “proven base layer protocols”: they are just a few years at max. Chromia is built on top of Postgresql, that has been used in enterprises for decades, a really proven technology. And the Java virtual machine on top of that. This is proven tech, at core.
Moh (Binance Angel)🇳🇬, Question No 4 :
What is Postchain?
Henrik Hjelte,
Postchain is an open-source product of ChromaWay for enterprise clients and it’s the core technology on which Chromia is built.
Postchain is a replicated blockchain and database that offers highly resilient distributed database management with distributed control.
Postchain is the only product on the market that combines the immutable consensus of a blockchain and the properties of a real database management system (You know, the tech that built SAP, Facebook, Banks…) …
Postchain allows you to share information between companies and/or individuals in a secure and transparent way.
That is the low-level base of Chromia you can say
Moh (Binance Angel)🇳🇬,
Can you please name some of your clients that are using this service already?
Serge,
You mean products built on Postchain? Also, Stockholm Green Digital Finance, Green Assets Wallet that’s now functioning on Chromia Bootstrap Mainnet.
Big financial institutions
It’s only a beginning of course, but very promising one. https://greenassetswallet.org/news/2019/12/12/launch-of-the-green-assets-wallet
Henrik Hjelte,
We got a lot of attention with the Swedish Land registry; we did a joint project between them and banks and a telco etc on postchain as base.
Then, right now we do a large project with the Inter-American Development bank also about land-registration (processes) in South America.
We had a client, Stockholm Green Digital Finance, that did a system for green bonds (tracking environmental impact. Yes, as Sege says, it was later moved to Chromia…
Which is cool. Also, another external development company did that phase of the project, proving that other can build on our tech,4irelabs from Ukraine is their name. Some companies using the GAW: Blackrock. SEB Bank etc…
Also, we have done more projects, in Australia, asia etc. Oh Daimler too (the Mercedes company) …
Moh (Binance Angel)🇳🇬,
Lots of enterprise clients you’ve got. No wonder I do see the meme “CHR=ETH KILLER”
Serge,
It’s a meme from our supporters. But we believe we can coexist:)
For some niche things eth is good :)
So, no killing :D
Henrik Hjelte,
We want to work with partners too for this, we can’t do all projects ourselves. Also, for Chromia projects, ChromaWay company can help do support maintenance etc. So, it is not competing, it adds value to the ecosystem.
Yeah ETH is good too, for some applications. We are friends with them from colored-coin times.
And colored-coins inspired ETH, and ETH inspires us.
Moh (Binance Angel)🇳🇬, Question No 5 :
Lastly, CHROMIA is already doing very well in terms of business. You just got listed on BINANCE JEX, you are on-boarding new clients and dishing out new features. But what’s next? Is there anything to be excited about?
Henrik Hjelte,
Plans for 2020 are to both release a series of dapps to showcase how fantastic Chromia is, as well as continue to develop the platform. And when it is secure and good enough, we will release the mainnet.
Dapps are now being made by us as well as others. We do a decentralized social network framework called Chromunity, now released to TestNet. It is really cool, users can vote over moderators, and in the future users might even govern the complete application, how it can be updated. This is a great showcase for Chromia and why we use the slogan Power to the Public.
https://testnet.chromunity.com/
Games coming are:
Mines of Dalarnia (by Workinman Interactive). An action game in a mine with blockchain rental of plots and stuff. Already on TestNet and you can take a peek on it at https://www.minesofdalarnia.com
more coming…
Krystopia 2, novas journey. A puzzle game done by Antler Interactive. Could only find trailer though: https://www.youtube.com/watch?v=-G95-Dw3kI4
However, we have even larger ambitions with blockchain gaming…
We are doing A secret demo-project that we do together with Antler to showcase the technical potential of Chromia platform.
Another exciting relase is an indie game Chain of Alliance, done by two external developers. It is a strategy game with full-logic on blockchain. Public release on TestNet on May 22!
More coming in 2020: Other dapps from other companies, one in impact-tech.
That is a serious app, Chromia also works outside gaming and social media for enterprises and startups
And I hope some of you will do something, we want to support dapps on the platform so reach out to us…
Moh (Binance Angel)🇳🇬,
When can we be expecting the mainnet? Any approximate time? I’m sure the community will really excited to have that info
Serge,
It’s now in Bootstap phase, so it’s technically already functioning. MVP will be very soon
Stay tuned;)
Twitter questions Vs answers
Ellkayy,
What’s the unique thing in Chromia that no other blockchain has, that makes you the better option?
Henrik Hjelte,
Unique: Chromia is the only blockchain that also has a real, proper database built-in. And blockchain is about managing data in a shared context. How to best managed data was solved in computer science already. So far, it is the relational algebra model that is used in 100% of all enterprises, and has an 85% market share. Chromia is the only blockchain that use that model and that power.
Ellkayy,
Why Chromia use RELL and not SQL or JavaScript? Can developers with other language knowledge use Chromia?
Serge,
Rell is the only language on the blockchain side. You can combine with anything on client-side, although now client only exists for JS/TS, C# and Java/Kotlin. Rell is a language for relational blockchain programming. It combines the following features:
1 Relational data modeling and queries similar to SQL. People familiar with SQL should feel at home once they learn the new syntax.
2 Normal programming constructs: variables, loops, functions, collections, etc.
3 Constructs which specifically target application backends and, in particular, blockchain-style programming including request routing, authorization, etc.
Rell aims to make programming as convenient and simple as possible. It minimizes boilerplate and repetition. At the same time, as a static type system it can detect and prevent many kinds of defects prior to run-time.
Roshan DV,
I have been monitoring your project for a while but some concerns about it: Your project will build your own core network, so you have more visibility than Ethereum and NEO. These are projects that were born before and which also have a very large community. And what can assure you that your project will guarantee the functionalities that you have defined?
Henrik Hjelte,
What came first? I want to remind that Vitalik was in the colored-coins project, led by our CTO and we had blockchain in production before ETH and NEO etc existed. We are the old dogs…
Large community: We are part of the same community. When developers are fustrated and want to try new tech, they go to us from other blockchains.
Also, we have a large potential: SQL (close to Rell and our tech) is the world top 3 language. Bigger than Java. Bigger than PHP. Only beaten bny HTML and javascript. Soliditiy is not on top 20 list. THere are millions of developers that know SQL. That is potential for community… (source is Stackoverflow annual programming survey).
Paul (Via Manage),
What are the utilities of Chromia and what purpose does the Chromia coin serve?
Serge,
Chromia meta-token called Chroma (CHR). It is used in Chromia to compensate block-producing nodes by fees. In Chromia, fees are paid by dapps, which can in their turn collect fees from users. Chromia provides mechanisms which balance the interests of developers and users. Dapp tokens can be automatically backed with Chroma, providing liquidity and value which is independent of investment into the dapp. Dapp investors can be compensated in Chroma through a profit-sharing contract. For developers, Chromia offers the opportunity to derive income from dapps. This incentivises the creation and maintenance of high quality dapps because better dapps generate more income and create more demand for tokens owned by the developer. The Chromia model is designed to support sustainable circular economies and foster a mutually beneficial relationship between developers, users, and investors.
Idemudia Isaac,
Thank you very much u/henrik_hjelte u/sergelubkin
You stated your plans for 2020 is to release series of dApps. What kind of large scale, mainstream decentralized application and $Chromia products do you think is suitable for the Nigerian environment?
Henrik Hjelte,
Actually, this is why we want to work with partners. We cannot know everything, For African market we have seen of course payments/remittances (but it has fallen out of trend). We would love to do real-estate /land-registration but we understand we need a strong local partner (more than a single person, a real company or organization driving).
●CC● | Elrond 🇵🇭,
What plans do you have to building a vibrant global community around Rell? And how would you go about encouraging/incentivising such ‘Rellists’ around the world to build dApps on Chromia? u/henrik_hjelte u/sergelubkin
Henrik Hjelte,
For developers (I am one too, or used to be) you normally need to prove a few things:
\ That the tech is productive (can I do apps faster?)*
\ That it is better (less bugs, more maintainable?)*
Then the community will come. We see that all the time. Look at web development. React.js came, and developers flooded to it. Not because of marketing on Superbowl, but because it was BETTER. Fewer bugs and easier to do complex webapps.
So, at core: people will come when we showcase the productivity gains, and that is what we need to focus on.
●CC● | Elrond 🇵🇭,
Why do you choose to build Chromia token on ERC20 instead of other blockchain such as BEP2, TRC20…or your own chain while ERC20 platform is very slow and have a case of fee? u/henrik_hjelte u/sergelubkin
Serge,
So far Ethereum has the best infrastructure, it’s the oldest and most reliable network for tokens. It also became the industry standard which exchanges utilize. We will transfer 80% of all erc20 tokens to our Chromia blockchain when it’s ready for that.
Koh,
In your whitepaper it says in the upcoming version of ChromiaWallet that it will be able to function as a Dapp browser for public use. Q) Will it be similar to the Dapp browser on Trust Wallet?
Serge,
It’s live already try it http://vault-testnet.chromia.com/
It’s the wallet and a dapp browser
CHROMIA is SOLID,
Your metamorphosis is a laudable one,surviving different FUD, how have you been able to survive this longest bear market and continue building and developing cos many projects have died out in this time period!
Henrik Hjelte,
You need to know we started a company before ETH existed. There was 0 money in blockchain when we started. I did it becuase it was fun, exciting tech and MAYBE someone would be interested in the thing we made “Tokens”…
We were never in the crazy bull-market, manly observed the crazies from the side. We fundraised for CHR in a dip (they called it bear market). ChromaWay the company also make money from enterprises.
Алекс,
What is SSO?
What makes it important for chromias ecosystem?
Why should we users be attracted to it?’
Serge,
Chromia SSO is perhaps the most important UX improvement that Chromia offers the decentralized world. It revolutionizes the way users interact with dapps. Any dapp requires users to sign transactions, that means they need a private key. Control of the private key is control of any and all dapps or assets associated with it. This means that private keys have an especially stringent set of security requirements in a blockchain context — they control real value, and there is no recourse if they are compromised or lost. https://blog.chromia.com/chromia-sso-the-whys-and-the-whats/
Olufemi Joel,
How do you see the Chromia project developing in 3 to 5 years, both on the commercial level and on the evolution of the company? What are the plans for expansion in different regions? Are you going to outsource the team/skills or keep it centralized and set up offices?
Henrik Hjelte,
I take part of the question. On outsource: we were a distributed team from day one, with co-founders from 3 countries (still living there). We are distributed now, Ukraine, Sweden, Vietnam, Croatia, China are “hubs” then we have individuals too. No big plan, just where we found great developers…
Park Lee, u/henrik_hjelte
You claim CHOROMIA have fast support, useful features with an affordable service cost. That fast and the fees are cheap but can you guarantee stability?
What’s the Algorithms which are used by CHROMIA for that fast? And Can you explain it?
Serge,
We use PBFT protocol with some features of DPOS, this plus sidechains parallelism offers almost unlimited speed and scalability. We also use the feature called anchoring to secure all transactions in batches on Bitcoin blockchain.
Mario Boy,
What are you guys trying to achieve as an end goal? The next Ethereum? Or the next enterprise version of Ethereum? Or something different?
Henrik Hjelte,
The end goal… good question. When we started in 2014 there were no other blockchain companies, so we wanted to do the best blockchain technology in order to enable a decentralized world with more fair applications. And that is what we still do. Technology/software that can enable people to make a fairer world
Erven James Sato,
“STAKING” is one of the STRATEGIES to ATTRACT USERS and ACHIEVE MASS ADOPTION
Does your GREAT PROJECT have plan about Staking?
Serge,
Yes, we announced our staking plans couple of months ago https://blog.chromia.com/on-providers-and-stakes/
We are working with our current partners to make it accessible for general public.
Chizoba,
I often see Chromia and ChromaWay being used interchangeably, what is the relationship between the two?
Henrik Hjelte,
ChromaWay the company started Chromia from code done as postchain. This is normal in open-source development, a company that leads development. But Chromia will be a decentalized network, so ChromaWay will not make direct money out of it more than if we have a role as a Provider (and get payed for hosting). ChromaWay can indirectly make money from optional support and maintenance etc. Also, this, perfectly normal in open-source world.
And it also benefits Chromia that there is a market for support.
A market open for competition.
No special treatment for “ChromaWay”
Enajite,
How to start coding on Chromia?
Henrik Hjelte,
Go to https://rell.chromia.com and follow the tutorial. Enjoy the free time you get compared to other blockchain languages…
●CC● | Elrond 🇵🇭,
Chromia process 500 TPS, these is slow compare to other Blockchains, where we can see now 60K TPS if more capacity require, how can that be? u/henrik_hjelte u/sergelubkin
Serge,
Yes, if you need faster speed you can use parallelism by having multiple blockchains for your dapp. Also, by optimization and better architecture sky is the limit.
Delphino.eth ⟠,
Can we consider Chromia an hybrid? For its mixing of Blockchain and a Database?
Henrik Hjelte,
Yes and no. I want to stress that Chromia is a FULL blockchain. It is not only “inspired”. It is a blockchain AND a database.
I tend to think about Hybrid more in the usecases that you might have as a customer. For example, a bank might want to have some data/transactions private (as a private blockchain) and have another half of the application with public data (on Chromia). So that is a hybrid solution, and Chromia ROCKS in that segment since it is the only blockchain that is complete relational database (what the normal world uses anyway for 85% of all applications)
Example area: “open banking”
Steve bush,
How will Chromia I have any empower Investors, Companies, Developers, Platform Users to
deliver impactful solutions and bring value to people all over the world?
Henrik Hjelte,
In order to make blockchain go big, we need to have users. Users need to be able to use apps with ease. Chromia have features like single-sign on (ease of use), but importantly do not require owning tokens to USE apps.
Also, it needs to be easy to make applications. For example, if you are a student in US and came up with an idea, you want to make an application for your school. Let’s call it “thefacebook”. You code something in PHP and MySQL. DID YOU SEE THAT. SQL. SQL.SQL. It is the same tech that Chromia has but no one else in the blockchain business. SQL rules the world if you look outside the crypto bubble. Google the Oracle head-office… 100% of all enterprises use it… Because it is easy and powerful.
And we even improve on SQL with Rell….
So, compare that with a hacky virtual machine that have a few years…. 😊
August,
“Mines of Dalarnia” is a game that has caught my attention a lot, due to its simplicity and quality. But in the time that I have used it I have not been able to differentiate between the Chromia blockchain of this game and that of the competition? What other games do you have next to develop? I would like to give ideas in those games like a Gamers!
Henrik Hjelte,
We thought about in corona time sports club might want to engage more with their fans digitally. And of course, E-Sports is getting a real momentum as the young generation grows up. Now a bit sad that all games are centralized. My daughter will be sad when (at some day?) they will close down roblox… it happens to all centralized apps eventually… that is what we fix. Power to the Public to control apps and their future. I’ll repost again Alex post. Sorry I like it a lot… https://blog.chromia.com/towards-publicly-hosted-applications/
Bisolar,
Good day Chromia team from a Chromia fan
Can you tell us Chromia’s geographical focus at the moment and the proces it follows for it BUSINESS DEVELOPMENT?
What factors do you consider before identifying NEW MARKETS to enter?
Serge,
Chromia will initially focus on community building in China, Korea, US and Europe. The focus of community growth will gradually expand to other markets as the project gains popularity.
Current community growth strategies of Chromia include:
Chromia blockchain incubator creation to welcome more projects to the Chromia blockchain
Host blockchain gaming conferences, workshops, and meetups to engage with potential users.
Provide online and face-to-face tutorials to engage with dapps developers.
Attract blockchain developers through direct and indirect approach via specialized platforms and communities.
Develop our relations with existing and previous corporate clients, and their partnership networks to participate in their blockchain ventures
Launch Node program to encourage system providers to run nodes on the Chromia blockchain.
Staking program for Chroma (CHR) tokens
Active community engagement via social channels.
Future community growth strategies of Chromia after Mainnet launch include:
Partner with more gaming studios, startups and enterprises
Build local communities with Ambassador Programs.
Partner with external incubator and accelerators to provide blockchain expertise and introduce projects to Chromia ecosystem
Continue organizing hackathons around the world to attract more developers.
Emmanuel,
I want to know the current structure of your roadmap? What is the future roadmap of CHROMIA? Is there any key milestone coming???
Henrik Hjelte,
It is easy to do a roadmap; anyone can make a pape plan. But I think they are used in the wrong way. Software is hard, blockchain is even harder because it NEEDS TO BE SECURE. No MVP releases. We cannot even have roadmap deadlines and skimp on quality. Where we are now though is: Rell language finished so much that developers can write apps and see its magic. We have external devs doing dapps. We have the first phase of mainnet. We have a series of releases coming up. We will release mainnet when it is secure enough, and gradual roll out. I think quite soon, development is going great at the moment, a bit quicker than we though.
Ellkayy,
Why doesn’t Chromia transactions use gas? How do you power transactions then?
Serge,
Main feature of gas in Ethereum is to pay for transactions for miners get rewards. In our scenario Providers get rewards from dapp owners. So dapp owner pays for storing their dapp. It’s like Amazon Web Service model. Then dapp owner can monetize it in its own way.
Ellkayy,
Many developers don’t know RELL, just Solidity and SQL. Is this a barrier or threat to Chromia? Why RELL is better?
Henrik Hjelte,
Very few developers know Solidity. Do a search on github. I referred previously to stackoverflow programming language survey results. https://insights.stackoverflow.com/survey/2019#technology
If you know SQL, you learn Rell in a day.
SQL is the top 3 language here. I’d say there are millions that can easily jump to Rell.
Soldity or other blockchains, not on top 20 list even.
Rell is a hipper, nicer version of SQL that is also a “normal” programming language.
Developers like to learn new things, new languages. Otherwise we would be stuck with PHP, the DOMINANT language. Well, is it still? Seems javascript and react.js and node etc is taking over…
Moh (Binance Angel)🇳🇬,
This brings us to the end of the AMA. It’s been a pleasure being with all of you, THANK YOU. Special shout out to u/sergelubkin and u/henrik_hjelte for honouring us with their presence today❤️
Kindly follow CHROMIA on twitter and join the conversation with their community on Telegram
Twitter: https://twitter.com/Chromia
Telegram: https://t.me/hellochromia
Official Chromia Nigeria Community Channel 🇳🇬 : https://t.me/ChromiaNigeria
Website: www.chromia.com
submitted by dam30 to Teamchromia [link] [comments]

/r/Monero - Newcomers Please Read. Everything You Need To Know.

What is Monero (XMR)?
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Poloniex
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Livecoin
BTER
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BTER
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Bithumb
Where can I find a good mining pool?
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What miner should I use?
CPU:
XMR-Stak (Windows-Linux)
CpuMiner by tpruvot (Windows, Linux)
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XMR-stak (AMD)
Ccminer (nVidia) by KlausT, psychocrypt, and fireice-uk
Claymore's CryptoNote GPU Miner (AMD)
If you are a Windows user, click here.
Can I use a proxy for mining?
You can use XMR Proxy. If you want to monitor your rigs you can use Monero Mining Monitor.
How can I setup a local wallet while running node with little bandwidth?
You can use GUI, as a remote node as it uses very little bandwidth. Go to settings tab and change: "localhost:18089" to "node.moneroworld.com:18089". If you are still having problems, then just use our Monero Web-Wallet.
Can I run Monero through Tor or I2P?
Guide to use Monero with Tor correctly
Monero Safety Through Tor
Monero I2P
My vendor only accepts bitcoin but I only have Monero, and I know bitcoin is not private/anonymous. What should I do?
Use XMR.TO, but you should also educate them about bitcoins lack of privacy. Tell them to visit this post.
How long does it take to sync to the blockchain?
It can take from a few hours (using SSD drive) or even 24 hours, depending on hard drive and connection speed.
How do I generate a QR-code for a Monero address?
How to generate a QR code for a Monero address
Moneroqrcode.com for a personalized code
Guide to check balance
List of scams: (Always do a background check / research for anything outside of official releases.)
Did you know over 50 high profile artists accept Monero on their online stores? Check out Project Coral Reef
Are there any other sub-reddits that specialize in certain parts of Monero or just related to Monero?
Yes, there are a few. However, please keep in mind that this sub-reddit (/Monero) is the official Monero sub-reddit.
/xmrtrader - Trading, and investing related discussions & inquires.
/MoneroMining - Mining related discussions & inquires.
/MoneroCommunity for those who want to help grow the community.
/moonero for shitposts and memes.
/MoneroMarket for buying and selling wares for Monero.
/MoneroSupport for, you guessed it, Monero support.
Want to get involved? Click here for a list of sources.
How can I participate in the Monero community?
We welcome everyone to join us and help out. Check the "Community Info" section on our subreddit for our website, forum, stack exchange, github, twitter, and facebook. Anyway, we hope you stick around beyond the hype. Monero has a lot going for it, and we hope you agree! We really need your help, since this project is entirely driven by the community!
Nun vi spertis liberecon.
submitted by cryptonaire- to Monero [link] [comments]

Information and FAQ

Welcome to the official IOTA subreddit.
If you are new you can find lots of information here, in the sidebar and please use the search button to see if your questions have been asked before. Please focus discussion on IOTA technology, ecosystem announcements, project development, apps, etc. Please direct help questions to /IOTASupport, and price discussions and market talk to /IOTAmarkets.
Before getting started it is recommended to read the IOTA_Whitepaper.pdf. I also suggest watching these videos first to gain a better understanding.
IOTA BREAKDOWN: The Tangle Vs. Blockchain Explained
IOTA tutorial 1: What is IOTA and some terminology explained

Information

Firstly, what is IOTA?

IOTA is an open-source distributed ledger protocol launched in 2015 that goes 'beyond blockchain' through its core invention of the blockless ‘Tangle’. The IOTA Tangle is a quantum-resistant Directed Acyclic Graph (DAG), whose digital currency 'iota' has a fixed money supply with zero inflationary cost.
IOTA uniquely offers zero-fee transactions & no fixed limit on how many transactions can be confirmed per second. Scaling limitations have been removed, since throughput grows in conjunction with activity; the more activity, the more transactions can be processed & the faster the network. Further, unlike blockchain architecture, IOTA has no separation between users and validators (miners / stakers); rather, validation is an intrinsic property of using the ledger, thus avoiding centralization.
IOTA is focused on being useful for the emerging machine-to-machine (m2m) economy of the Internet-of-Things (IoT), data integrity, micro-/nano- payments, and other applications where a scalable decentralized system is warranted.
More information can be found here.

Seeds

A seed is a unique identifier that can be described as a combined username and password that grants you access to your IOTA.
Your seed is used to generate the addresses and private keys you will use to store and send IOTA, so this should be kept private and not shared with anyone. If anyone obtains your seed, they can generate the private keys associated with your addresses and access your IOTA.

Non reusable addresses

Contrary to traditional blockchain based systems such as Bitcoin, where your wallet addresses can be reused, IOTA's addresses should only be used once (for outgoing transfers). That means there is no limit to the number of transactions an address can receive, but as soon as you've used funds from that address to make a transaction, this address should not be used anymore.
Why?
When an address is used to make an outgoing transaction, a random 50% of the private key of that particular address is revealed in the transaction signature, which effectively reduces the security of the key. A typical IOTA private key of 81-trits has 2781 possible combinations ( 8.7 x 10115 ) but after a single use, this number drops to around 2754 ( 2 x 1077 ), which coincidentally is close to the number of combinations of a 256-bit Bitcoin private key. Hence, after a single use an IOTA private key has about the same level of security as that of Bitcoin and is basically impractical to brute-force using modern technology. However, after a second use, another random 50% of the private key is revealed and the number of combinations that an attacker has to guess decreases very sharply to approximately 1.554 (~3 billion) which makes brute-forcing trivial even with an average computer.
Note: your seed is never revealed at at time; only private keys specific to each address.
The current light wallet prevents address reuse automatically for you by doing 2 things:
  1. Whenever you make an outgoing transaction from an address that does not consume its entire balance (e.g. address holds 10 Mi but you send only 5 Mi), the wallet automatically creates a new address and sends the change (5 Mi) to the new address.
  2. The wallet prevents you from performing a second outgoing transaction using the same address (it will display a “Private key reuse detected!” error).
This piggy bank diagram can help visualize non reusable addresses. imgur link
[Insert new Safe analogy].

Address Index

When a new address is generated it is calculated from the combination of a seed + Address Index, where the Address Index can be any positive Integer (including "0"). The wallet usually starts from Address Index 0, but it will skip any Address Index where it sees that the corresponding address has already been attached to the tangle.

Private Keys

Private keys are derived from a seeds key index. From that private key you then generate an address. The key index starting at 0, can be incremented to get a new private key, and thus address.
It is important to keep in mind that all security-sensitive functions are implemented client side. What this means is that you can generate private keys and addresses securely in the browser, or on an offline computer. All libraries provide this functionality.
IOTA uses winternitz one-time signatures, as such you should ensure that you know which private key (and which address) has already been used in order to not reuse it. Subsequently reusing private keys can lead to the loss of funds (an attacker is able to forge the signature after continuous reuse).
Exchanges are advised to store seeds, not private keys.

FAQ

Buying IOTA

How do I to buy IOTA?

Currently not all exchanges support IOTA and those that do may not support the option to buy with fiat currencies.
Visit this website for a Guide: How to buy IOTA
or Click Here for a detailed guide made by 450LbsGorilla

Cheapest way to buy IOTA?

You can track the current cheapest way to buy IOTA at IOTA Prices.
It tells you where & how to get the most IOTA for your money right now. There's an overview of the exchanges available to you and a buying guide to help you along.
IOTAPrices.com monitors all major fiat exchanges for their BTC & ETH rates and combines them with current IOTA rates from IOTA exchanges for easy comparison. Rates are taken directly from each exchange's official websocket. For fiat exchanges or exchanges that don't offer websockets, rates are refreshed every 60 seconds.

What is MIOTA?

MIOTA is a unit of IOTA, 1 Mega IOTA or 1 Mi. It is equivalent to 1,000,000 IOTA and is the unit which is currently exchanged.
We can use the metric prefixes when describing IOTA e.g 2,500,000,000 i is equivalent to 2.5 Gi.
Note: some exchanges will display IOTA when they mean MIOTA.

Can I mine IOTA?

No you can not mine IOTA, all the supply of IOTA exist now and no more can be made.
If you want to send IOTA, your 'fee' is you have to verify 2 other transactions, thereby acting like a minenode.

Storing IOTA

Where should I store IOTA?

It is not recommended to store large amounts of IOTA on the exchange as you will not have access to the private keys of the addresses generated.

Wallets

GUI Desktop (Full Node + Light Node)
Version = 2.5.6
Download: GUI v2.5.6
Guide: Download/Login Guide
Nodes: Status
Headless IRI (Full Node)
Version = 1.4.1.4
Download: Mainnet v1.4.1.4
Guide:
Find Neighbours: /nodesharing
UCL Desktop/Android/iOS (Light Node)
Version = Private Alpha Testing
Website: iota-ucl (Medium)
Android (Light Node)
Version = Beta
Download: Google Play
iOS (Light Node)
Version = Beta Testing
Website: https://iota.tools/wallet
Paper Wallet
Version = v1.3.6
Repo: GitHub
Seed Vault
Version = v1.0.2
Repo: GitHub7

What is a seed?

A seed is a unique identifier that can be described as a combined username and password that grants you access to your wallet.
Your seed is used to generate the addresses linked to your account and so this should be kept private and not shared with anyone. If anyone obtains your seed, they can login and access your IOTA.

How do I generate a seed?

You must generate a random 81 character seed using only A-Z and the number 9.
It is recommended to use offline methods to generate a seed, and not recommended to use any non community verified techniques. To generate a seed you could:

On a Linux Terminal

use the following command:
 cat /dev/urandom |tr -dc A-Z9|head -c${1:-81} 

On a Mac Terminal

use the following command:
 cat /dev/urandom |LC_ALL=C tr -dc 'A-Z9' | fold -w 81 | head -n 1 

With KeePass on PC

A helpful guide for generating a secure seed on KeePass can be found here.

With a dice

Dice roll template

Is my seed secure?

  1. All seeds should be 81 characters in random order composed of A-Z and 9.
  2. Do not give your seed to anyone, and don’t keep it saved in a plain text document.
  3. Don’t input your seed into any websites that you don’t trust.
Is Someone Going To Guess My IOTA Seed?
What are the odds of someone guessing your seed?
  • IOTA seed = 81 characters long, and you can use A-Z, 9
  • Giving 2781 = 8.7x10115 possible combinations for IOTA seeds
  • Now let's say you have a "super computer" letting you generate and read every address associated with 1 trillion different seeds per second.
  • 8.7x10115 seeds / 1x1012 generated per second = 8.7x10103 seconds = 2.8x1096 years to process all IOTA seeds.

Why does balance appear to be 0 after a snapshot?

When a snapshot happens, all transactions are being deleted from the Tangle, leaving only the record of how many IOTA are owned by each address. However, the next time the wallet scans the Tangle to look for used addresses, the transactions will be gone because of the snapshot and the wallet will not know anymore that an address belongs to it. This is the reason for the need to regenerate addresses, so that the wallet can check the balance of each address. The more transactions were made before a snapshot, the further away the balance moves from address index 0 and the more addresses have to be (re-) generated after the snapshot.

What happens if you reuse an address?

It is important to understand that only outgoing transactions reveal the private key and incoming transactions do not. If you somehow manage to receive iotas using an address after having used it previously to send iotas—let's say your friend sends iotas to an old address of yours—these iotas may be at risk.
Recall that after a single use an iota address still has the equivalent of 256-bit security (like Bitcoin) so technically, the iotas will still be safe if you do not try to send them out. However, you would want to move these iotas out eventually and the moment you try to send them out, your private key will be revealed a second time and it now becomes feasible for an attacker to brute-force the private key. If someone is monitoring your address and spots a second use, they can easily crack the key and then use it to make a second transaction that will compete with yours. It then becomes a race to see whose transaction gets confirmed first.
Note: The current wallet prevents you from reusing an address to make a second transaction so any iotas you receive with a 'used' address will be stuck. This is a feature of wallet and has nothing to do with the fundamental workings of IOTA.

Sending IOTA

What does attach to the tangle mean?

The process of making an transaction can be divided into two main steps:
  1. The local signing of a transaction, for which your seed is required.
  2. Taking the prepared transaction data, choosing two transactions from the tangle and doing the POW. This step is also called “attaching”.
The following analogy makes it easier to understand:
Step one is like writing a letter. You take a piece of paper, write some information on it, sign it at the bottom with your signature to authenticate that it was indeed you who wrote it, put it in an envelope and then write the recipient's address on it.
Step two: In order to attach our “letter” (transaction), we go to the tangle, pick randomly two of the newest “letters” and tie a connection between our “letter” and each of the “letters” we choose to reference.
The “Attach address” function in the wallet is actually doing nothing else than making an 0 value transaction to the address that is being attached.

Why is my transaction pending?

IOTA's current Tangle implementation (IOTA is in constant development, so this may change in the future) has a confirmation rate that is ~66% at first attempt.
So, if a transaction does not confirm within 1 hour, it is necessary to "reattach" (also known as "replay") the transaction one time. Doing so one time increases probability of confirmation from ~66% to ~89%.
Repeating the process a second time increases the probability from ~89% to ~99.9%.

How do I reattach a transaction.

Reattaching a transaction is different depending on where you send your transaction from. To reattach using the GUI Desktop wallet follow these steps:
  1. Click 'History'.
  2. Click 'Show Bundle' on the 'pending' transaction.
  3. Click 'Reattach'.
  4. Click 'Rebroadcast'. (optional, usually not required)
  5. Wait 1 Hour.
  6. If still 'pending', repeat steps 1-5 once more.

Does the private key get revealed each time you reattach a transaction?

When you use the reattach function in the desktop wallet, a new transaction will be created but it will have the same signature as the original transaction and hence, your private key will not revealed a second time.

What happens to pending transactions after a snapshot?

IOTA Network and Nodes

What incentives are there for running a full node?

IOTA is made for m2m economy, once wide spread adoption by businesses and the IOT, there will be a lot of investment by these businesses to support the IOTA network. In the meantime if you would like to help the network and speed up p2p transactions at your own cost, you can support the IOTA network by setting up a Full Node.
Running a full node also means you don't have to trust a 3rd party light node provider. By running a full node you get to take advantage of new features that might not be installed on 3rd party nodes.

How to set up a full node?

To set up a full node you will need to follow these steps:
  1. Download the full node software: either GUI, or headless CLI for lower system requirements and better performance.
  2. Get a static IP for your node.
  3. Join the network by adding 7-9 neighbours.
  4. Keep your full node up and running as much as possible.
A detailed user guide on how to set up a VTS IOTA Full Node from scratch can be found here.

How do I get a static IP?

To learn how to setup a hostname (~static IP) so you can use the newest IOTA versions that have no automated peer discovery please follow this guide.

How do I find a neighbour?

Are you a single IOTA full node looking for a partner? You can look for partners in these place:

Resources

You can find a wiki I have been making here.
More to come...
If you have any contributions or spot a mistake or clarification, please PM me or leave a comment.
submitted by Boltzmanns_Constant to Iota [link] [comments]

Agreement with Satoshi – On the Formalization of Nakamoto Consensus

Cryptology ePrint Archive: Report 2018/400
Date: 2018-05-01
Author(s): Nicholas Stifter, Aljosha Judmayer, Philipp Schindler, Alexei Zamyatin, Edgar Weippl

Link to Paper


Abstract
The term Nakamoto consensus is generally used to refer to Bitcoin's novel consensus mechanism, by which agreement on its underlying transaction ledger is reached. It is argued that this agreement protocol represents the core innovation behind Bitcoin, because it promises to facilitate the decentralization of trusted third parties. Specifically, Nakamoto consensus seeks to enable mutually distrusting entities with weak pseudonymous identities to reach eventual agreement while the set of participants may change over time. When the Bitcoin white paper was published in late 2008, it lacked a formal analysis of the protocol and the guarantees it claimed to provide. It would take the scientific community several years before first steps towards such a formalization of the Bitcoin protocol and Nakamoto consensus were presented. However, since then the number of works addressing this topic has grown substantially, providing many new and valuable insights. Herein, we present a coherent picture of advancements towards the formalization of Nakamoto consensus, as well as a contextualization in respect to previous research on the agreement problem and fault tolerant distributed computing. Thereby, we outline how Bitcoin's consensus mechanism sets itself apart from previous approaches and where it can provide new impulses and directions to the scientific community. Understanding the core properties and characteristics of Nakamoto consensus is of key importance, not only for assessing the security and reliability of various blockchain systems that are based on the fundamentals of this scheme, but also for designing future systems that aim to fulfill comparable goals.

References
[AAC+05] Amitanand S Aiyer, Lorenzo Alvisi, Allen Clement, Mike Dahlin, Jean-Philippe Martin, and Carl Porth. Bar fault tolerance for cooperative services. In ACM SIGOPS operating systems review, volume 39, pages 45–58. ACM, 2005.
[ABSFG08] Eduardo A Alchieri, Alysson Neves Bessani, Joni Silva Fraga, and Fab´ıola Greve. Byzantine consensus with unknown participants. In Proceedings of the 12th International Conference on Principles of Distributed Systems, pages 22–40. SpringerVerlag, 2008.
[AFJ06] Dana Angluin, Michael J Fischer, and Hong Jiang. Stabilizing consensus in mobile networks. In Distributed Computing in Sensor Systems, pages 37–50. Springer, 2006.
[AJK05] James Aspnes, Collin Jackson, and Arvind Krishnamurthy. Exposing computationally-challenged byzantine impostors. Department of Computer Science, Yale University, New Haven, CT, Tech. Rep, 2005.
[AMN+16] Ittai Abraham, Dahlia Malkhi, Kartik Nayak, Ling Ren, and Alexander Spiegelman. Solidus: An incentive-compatible cryptocurrency based on permissionless byzantine consensus. https://arxiv.org/abs/1612.02916, Dec 2016. Accessed: 2017-02-06.
[AS98] Yair Amir and Jonathan Stanton. The spread wide area group communication system. Technical report, TR CNDS-98-4, The Center for Networking and Distributed Systems, The Johns Hopkins University, 1998.
[Bag00] Walter Bagehot. The english constitution, volume 3. Kegan Paul, Trench, Trubner, 1900. ¨
[Ban98] Bela Ban. Design and implementation of a reliable group communication toolkit for java, 1998.
[BBRTP07] Roberto Baldoni, Marin Bertier, Michel Raynal, and Sara Tucci-Piergiovanni. Looking for a definition of dynamic distributed systems. In International Conference on Parallel Computing Technologies, pages 1–14. Springer, 2007.
[Bit] Bitcoin community. Bitcoin-core source code. https://github.com/bitcoin/bitcoin. Accessed: 2015-06-30.
[BJ87] Ken Birman and Thomas Joseph. Exploiting virtual synchrony in distributed systems. volume 21. ACM, 1987.
[BMC+15] Joseph Bonneau, Andrew Miller, Jeremy Clark, Arvind Narayanan, Joshua A Kroll, and Edward W Felten. Sok: Research perspectives and challenges for bitcoin and cryptocurrencies. In IEEE Symposium on Security and Privacy, 2015.
[BO83] Michael Ben-Or. Another advantage of free choice (extended abstract): Completely asynchronous agreement protocols. In Proceedings of the second annual ACM symposium on Principles of distributed computing, pages 27–30. ACM, 1983.
[BPS16a] Iddo Bentov, Rafael Pass, and Elaine Shi. The sleepy model of consensus. https://eprint.iacr.org/2016/918.pdf, 2016. Accessed: 2016-11-08.
[BPS16b] Iddo Bentov, Rafael Pass, and Elaine Shi. Snow white: Provably secure proofs of stake. https://eprint.iacr.org/2016/919.pdf, 2016. Accessed: 2016-11-08.
[BR09] Franc¸ois Bonnet and Michel Raynal. The price of anonymity: Optimal consensus despite asynchrony, crash and anonymity. In Proceedings of the 23rd international conference on Distributed computing, pages 341–355. Springer-Verlag, 2009.
[Bre00] EA Brewer. Towards robust distributed systems. abstract. In Proceedings of the Nineteenth Annual ACM Symposium on Principles of Distributed Computing, page 7, 2000.
[BSAB+17] Shehar Bano, Alberto Sonnino, Mustafa Al-Bassam, Sarah Azouvi, Patrick McCorry, Sarah Meiklejohn, and George Danezis. Consensus in the age of blockchains. arXiv:1711.03936, 2017. Accessed:2017-12-11.
[BT16] Zohir Bouzid and Corentin Travers. Anonymity-preserving failure detectors. In International Symposium on Distributed Computing, pages 173–186. Springer, 2016.
[Can00] Ran Canetti. Security and composition of multiparty cryptographic protocols. Journal of CRYPTOLOGY, 13(1):143–202, 2000.
[Can01] Ran Canetti. Universally composable security: A new paradigm for cryptographic protocols. In Foundations of Computer Science, 2001. Proceedings. 42nd IEEE Symposium on, pages 136–145. IEEE, 2001.
[CFN90] David Chaum, Amos Fiat, and Moni Naor. Untraceable electronic cash. In Proceedings on Advances in cryptology, pages 319–327. Springer-Verlag New York, Inc., 1990.
[CGR07] Tushar D Chandra, Robert Griesemer, and Joshua Redstone. Paxos made live: an engineering perspective. In Proceedings of the twenty-sixth annual ACM symposium on Principles of distributed computing, pages 398–407. ACM, 2007.
[CGR11] Christian Cachin, Rachid Guerraoui, and Luis Rodrigues. Introduction to reliable and secure distributed programming. Springer Science & Business Media, 2011.
[CKS00] Christian Cachin, Klaus Kursawe, and Victor Shoup. Random oracles in constantinople: Practical asynchronous byzantine agreement using cryptography. In Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing, pages 123–132. ACM, 2000.
[CL+99] Miguel Castro, Barbara Liskov, et al. Practical byzantine fault tolerance. In OSDI, volume 99, pages 173–186, 1999.
[CL02] Miguel Castro and Barbara Liskov. Practical byzantine fault tolerance and proactive recovery. ACM Transactions on Computer Systems (TOCS), 20(4):398–461, 2002.
[CNV04] Miguel Correia, Nuno Ferreira Neves, and Paulo Verissimo. How to tolerate half less one byzantine nodes in practical distributed systems. In Reliable Distributed Systems, 2004. Proceedings of the 23rd IEEE International Symposium on, pages 174–183. IEEE, 2004.
[Coo09] J. L. Coolidge. The gambler’s ruin. Annals of Mathematics, 10(4):181–192, 1909.
[Cri91] Flaviu Cristian. Reaching agreement on processor-group membrship in synchronous distributed systems. Distributed Computing, 4(4):175–187, 1991.
[CT96] Tushar Deepak Chandra and Sam Toueg. Unreliable failure detectors for reliable distributed systems. volume 43, pages 225–267. ACM, 1996.
[CV17] Christian Cachin and Marko Vukolic. Blockchain con- ´sensus protocols in the wild. arXiv:1707.01873, 2017. Accessed:2017-09-26.
[CVL10] Miguel Correia, Giuliana S Veronese, and Lau Cheuk Lung. Asynchronous byzantine consensus with 2f+ 1 processes. In Proceedings of the 2010 ACM symposium on applied computing, pages 475–480. ACM, 2010.
[CVNV11] Miguel Correia, Giuliana Santos Veronese, Nuno Ferreira Neves, and Paulo Verissimo. Byzantine consensus in asynchronous message-passing systems: a survey. volume 2, pages 141–161. Inderscience Publishers, 2011.
[CWA+09] Allen Clement, Edmund L Wong, Lorenzo Alvisi, Michael Dahlin, and Mirco Marchetti. Making byzantine fault tolerant systems tolerate byzantine faults. In NSDI, volume 9, pages 153–168, 2009.
[DDS87] Danny Dolev, Cynthia Dwork, and Larry Stockmeyer. On the minimal synchronism needed for distributed consensus. volume 34, pages 77–97. ACM, 1987.
[Dei] Wei Dei. b-money. http://www.weidai.com/bmoney.txt. Accessed on 03/03/2017.
[DGFGK10] Carole Delporte-Gallet, Hugues Fauconnier, Rachid Guerraoui, and Anne-Marie Kermarrec. Brief announcement: Byzantine agreement with homonyms. In Proceedings of the twentysecond annual ACM symposium on Parallelism in algorithms and architectures, pages 74–75. ACM, 2010.
[DGG02] Assia Doudou, Benoˆıt Garbinato, and Rachid Guerraoui. Encapsulating failure detection: From crash to byzantine failures. In International Conference on Reliable Software Technologies, pages 24–50. Springer, 2002.
[DGKR17] Bernardo David, Peter Gazi, Aggelos Kiayias, and Alexan- ˇder Russell. Ouroboros praos: An adaptively-secure, semisynchronous proof-of-stake protocol. Cryptology ePrint Archive, Report 2017/573, 2017. Accessed: 2017-06-29.
[DLP+86] Danny Dolev, Nancy A Lynch, Shlomit S Pinter, Eugene W Stark, and William E Weihl. Reaching approximate agreement in the presence of faults. volume 33, pages 499–516. ACM, 1986.
[DLS88] Cynthia Dwork, Nancy Lynch, and Larry Stockmeyer. Consensus in the presence of partial synchrony. volume 35, pages 288–323. ACM, 1988.
[DN92] Cynthia Dwork and Moni Naor. Pricing via processing or combatting junk mail. In Annual International Cryptology Conference, pages 139–147. Springer, 1992.
[Dol81] Danny Dolev. Unanimity in an unknown and unreliable environment. In Foundations of Computer Science, 1981. SFCS’81. 22nd Annual Symposium on, pages 159–168. IEEE, 1981.
[Dou02] John R Douceur. The sybil attack. In International Workshop on Peer-to-Peer Systems, pages 251–260. Springer, 2002.
[DSU04] Xavier Defago, Andr ´ e Schiper, and P ´ eter Urb ´ an. Total order ´ broadcast and multicast algorithms: Taxonomy and survey. ACM Computing Surveys (CSUR), 36(4):372–421, 2004.
[DW13] Christian Decker and Roger Wattenhofer. Information propagation in the bitcoin network. In Peer-to-Peer Computing (P2P), 2013 IEEE Thirteenth International Conference on, pages 1–10. IEEE, 2013.
[EGSvR16] Ittay Eyal, Adem Efe Gencer, Emin Gun Sirer, and Robbert van Renesse. Bitcoin-ng: A scalable blockchain protocol. In 13th USENIX Security Symposium on Networked Systems Design and Implementation (NSDI’16). USENIX Association, Mar 2016.
[ES14] Ittay Eyal and Emin Gun Sirer. Majority is not enough: Bitcoin ¨ mining is vulnerable. In Financial Cryptography and Data Security, pages 436–454. Springer, 2014.
[Fin04] Hal Finney. Reusable proofs of work (rpow). http://web.archive.org/web/20071222072154/http://rpow.net/, 2004. Accessed: 2016-04-31.
[Fis83] Michael J Fischer. The consensus problem in unreliable distributed systems (a brief survey). In International Conference on Fundamentals of Computation Theory, pages 127–140. Springer, 1983.
[FL82] Michael J FISCHER and Nancy A LYNCH. A lower bound for the time to assure interactive consistency. volume 14, Jun 1982.
[FLP85] Michael J Fischer, Nancy A Lynch, and Michael S Paterson. Impossibility of distributed consensus with one faulty process. volume 32, pages 374–382. ACM, 1985.
[Fuz08] Rachele Fuzzati. A formal approach to fault tolerant distributed consensus. PhD thesis, EPFL, 2008.
[GHM+17] Yossi Gilad, Rotem Hemo, Silvio Micali, Georgios Vlachos, and Nickolai Zeldovich. Algorand: Scaling byzantine agreements for cryptocurrencies. Cryptology ePrint Archive, Report 2017/454, 2017. Accessed: 2017-06-29.
[GKL15] Juan Garay, Aggelos Kiayias, and Nikos Leonardos. The bitcoin backbone protocol: Analysis and applications. In Advances in Cryptology-EUROCRYPT 2015, pages 281–310. Springer, 2015.
[GKL16] Juan A. Garay, Aggelos Kiayias, and Nikos Leonardos. The bitcoin backbone protocol with chains of variable difficulty. http://eprint.iacr.org/2016/1048.pdf, 2016. Accessed: 2017-02-06.
[GKP17] Juan A. Garay, Aggelos Kiayias, and Giorgos Panagiotakos. Proofs of work for blockchain protocols. Cryptology ePrint Archive, Report 2017/775, 2017. http://eprint.iacr.org/2017/775.
[GKQV10] Rachid Guerraoui, Nikola Knezevi ˇ c, Vivien Qu ´ ema, and Marko ´ Vukolic. The next 700 bft protocols. In ´ Proceedings of the 5th European conference on Computer systems, pages 363–376. ACM, 2010.
[GKTZ12] Adam Groce, Jonathan Katz, Aishwarya Thiruvengadam, and Vassilis Zikas. Byzantine agreement with a rational adversary. pages 561–572. Springer, 2012.
[GKW+16] Arthur Gervais, Ghassan O Karame, Karl Wust, Vasileios ¨ Glykantzis, Hubert Ritzdorf, and Srdjan Capkun. On the security and performance of proof of work blockchains. https://eprint.iacr.org/2016/555.pdf, 2016. Accessed: 2016-08-10.
[GL02] Seth Gilbert and Nancy Lynch. Brewer’s conjecture and the feasibility of consistent, available, partition-tolerant web services. volume 33, pages 51–59. ACM, 2002.
[GRKC15] Arthur Gervais, Hubert Ritzdorf, Ghassan O Karame, and Srdjan Capkun. Tampering with the delivery of blocks and transactions in bitcoin. In Proceedings of the 22nd ACM SIGSAC Conference on Computer and Communications Security, pages 692–705. ACM, 2015.
[Her88] Maurice P Herlihy. Impossibility and universality results for wait-free synchronization. In Proceedings of the seventh annual ACM Symposium on Principles of distributed computing, pages 276–290. ACM, 1988.
[Her91] Maurice Herlihy. Wait-free synchronization. ACM Transactions on Programming Languages and Systems (TOPLAS), 13(1):124–149, 1991.
[HKZG15] Ethan Heilman, Alison Kendler, Aviv Zohar, and Sharon Goldberg. Eclipse attacks on bitcoin’s peer-to-peer network. In 24th USENIX Security Symposium (USENIX Security 15), pages 129–144, 2015.
[Hoe07] Jaap-Henk Hoepman. Distributed double spending prevention. In Security Protocols Workshop, pages 152–165. Springer, 2007.
[HT94] Vassos Hadzilacos and Sam Toueg. A modular approach to fault-tolerant broadcasts and related problems. Cornell University Technical Report 94-1425, 1994.
[IT08] Hideaki Ishii and Roberto Tempo. Las vegas randomized algorithms in distributed consensus problems. In 2008 American Control Conference, pages 2579–2584. IEEE, 2008.
[JB99] Ari Juels and John G Brainard. Client puzzles: A cryptographic countermeasure against connection depletion attacks. In NDSS, volume 99, pages 151–165, 1999.
[KMMS01] Kim Potter Kihlstrom, Louise E Moser, and P Michael MelliarSmith. The securering group communication system. ACM Transactions on Information and System Security (TISSEC), 4(4):371–406, 2001.
[KMMS03] Kim Potter Kihlstrom, Louise E Moser, and P Michael MelliarSmith. Byzantine fault detectors for solving consensus. volume 46, pages 16–35. Br Computer Soc, 2003.
[KMTZ13] Jonathan Katz, Ueli Maurer, Bjorn Tackmann, and Vassilis ¨ Zikas. Universally composable synchronous computation. In TCC, volume 7785, pages 477–498. Springer, 2013.
[KP15] Aggelos Kiayias and Giorgos Panagiotakos. Speed-security tradeoff s in blockchain protocols. https://eprint.iacr.org/2015/1019.pdf, Oct 2015. Accessed: 2016-10-17.
[KP16] Aggelos Kiayias and Giorgos Panagiotakos. On trees, chains and fast transactions in the blockchain. http://eprint.iacr.org/2016/545.pdf, 2016. Accessed: 2017-02-06.
[KRDO16] Aggelos Kiayias, Alexander Russell, Bernardo David, and Roman Oliynykov. Ouroboros: A provably secure proof-of-stake blockchain protocol. https://pdfs.semanticscholar.org/1c14/549f7ba7d6a000d79a7d12255eb11113e6fa.pdf, 2016. Accessed: 2017-02-20.
[Lam84] Leslie Lamport. Using time instead of timeout for fault-tolerant distributed systems. volume 6, pages 254–280. ACM, 1984.
[Lam98] Leslie Lamport. The part-time parliament. volume 16, pages 133–169. ACM, 1998.
[LCW+06] Harry C Li, Allen Clement, Edmund L Wong, Jeff Napper, Indrajit Roy, Lorenzo Alvisi, and Michael Dahlin. Bar gossip. In Proceedings of the 7th symposium on Operating systems design and implementation, pages 191–204. USENIX Association, 2006.
[LSM06] Brian Neil Levine, Clay Shields, and N Boris Margolin. A survey of solutions to the sybil attack. University of Massachusetts Amherst, Amherst, MA, 7, 2006.
[LSP82] Leslie Lamport, Robert Shostak, and Marshall Pease. The byzantine generals problem. volume 4, pages 382–401. ACM, 1982.
[LSZ15] Yoad Lewenberg, Yonatan Sompolinsky, and Aviv Zohar. Inclusive block chain protocols. In Financial Cryptography and Data Security, pages 528–547. Springer, 2015.
[LTKS15] Loi Luu, Jason Teutsch, Raghav Kulkarni, and Prateek Saxena. Demystifying incentives in the consensus computer. In Proceedings of the 22nd ACM SIGSAC Conference on Computer and Communications Security, pages 706–719. ACM, 2015.
[Lyn96] Nancy A Lynch. Distributed algorithms. Morgan Kaufmann, 1996.
[Mic16] Silvio Micali. Algorand: The efficient and democratic ledger. http://arxiv.org/abs/1607.01341, 2016. Accessed: 2017-02-09.
[Mic17] Silvio Micali. Byzantine agreement, made trivial. https://people.csail.mit.edu/silvio/SelectedApr 2017. Accessed:2018-02-21.
[MJ14] A Miller and LaViola JJ. Anonymous byzantine consensus from moderately-hard puzzles: A model for bitcoin. https://socrates1024.s3.amazonaws.com/consensus.pdf, 2014. Accessed: 2016-03-09.
[MMRT03] Dahlia Malkhi, Michael Merritt, Michael K Reiter, and Gadi Taubenfeld. Objects shared by byzantine processes. volume 16, pages 37–48. Springer, 2003.
[MPR01] Hugo Miranda, Alexandre Pinto, and Luıs Rodrigues. Appia, a flexible protocol kernel supporting multiple coordinated channels. In Distributed Computing Systems, 2001. 21st International Conference on., pages 707–710. IEEE, 2001.
[MR97] Dahlia Malkhi and Michael Reiter. Unreliable intrusion detection in distributed computations. In Computer Security Foundations Workshop, 1997. Proceedings., 10th, pages 116–124. IEEE, 1997.
[MRT00] Achour Mostefaoui, Michel Raynal, and Fred´ eric Tronel. From ´ binary consensus to multivalued consensus in asynchronous message-passing systems. Information Processing Letters, 73(5-6):207–212, 2000.
[MXC+16] Andrew Miller, Yu Xia, Kyle Croman, Elaine Shi, and Dawn Song. The honey badger of bft protocols. https://eprint.iacr.org/2016/199.pdf, 2016. Accessed: 2017-01-10.
[Nak08a] Satoshi Nakamoto. Bitcoin: A peer-to-peer electronic cash system. https://bitcoin.org/bitcoin.pdf, Dec 2008. Accessed: 2015-07-01.
[Nak08b] Satoshi Nakamoto. Bitcoin p2p e-cash paper, 2008.
[Nar16] Narayanan, Arvind and Bonneau, Joseph and Felten, Edward and Miller, Andrew and Goldfeder, Steven. Bitcoin and cryptocurrency technologies. https://d28rh4a8wq0iu5.cloudfront.net/bitcointech/readings/princeton bitcoin book.pdf?a=1, 2016. Accessed: 2016-03-29.
[Nei94] Gil Neiger. Distributed consensus revisited. Information processing letters, 49(4):195–201, 1994.
[NG16] Christopher Natoli and Vincent Gramoli. The blockchain anomaly. In Network Computing and Applications (NCA), 2016 IEEE 15th International Symposium on, pages 310–317. IEEE, 2016.
[NKMS16] Kartik Nayak, Srijan Kumar, Andrew Miller, and Elaine Shi. Stubborn mining: Generalizing selfish mining and combining with an eclipse attack. In 1st IEEE European Symposium on Security and Privacy, 2016. IEEE, 2016.
[PS16a] Rafael Pass and Elaine Shi. Fruitchains: A fair blockchain. http://eprint.iacr.org/2016/916.pdf, 2016. Accessed: 2016-11-08.
[PS16b] Rafael Pass and Elaine Shi. Hybrid consensus: Scalable permissionless consensus. https://eprint.iacr.org/2016/917.pdf, Sep 2016. Accessed: 2016-10-17.
[PS17] Rafael Pass and Elaine Shi. Thunderella: Blockchains with optimistic instant confirmation. Cryptology ePrint Archive, Report 2017/913, 2017. Accessed:2017-09-26.
[PSL80] Marshall Pease, Robert Shostak, and Leslie Lamport. Reaching agreement in the presence of faults. volume 27, pages 228–234. ACM, 1980.
[PSs16] Rafael Pass, Lior Seeman, and abhi shelat. Analysis of the blockchain protocol in asynchronous networks. http://eprint.iacr.org/2016/454.pdf, 2016. Accessed: 2016-08-01.
[Rab83] Michael O Rabin. Randomized byzantine generals. In Foundations of Computer Science, 1983., 24th Annual Symposium on, pages 403–409. IEEE, 1983.
[Rei96] Michael K Reiter. A secure group membership protocol. volume 22, page 31, 1996.
[Ric93] Aleta M Ricciardi. The group membership problem in asynchronous systems. PhD thesis, Cornell University, 1993.
[Ros14] M. Rosenfeld. Analysis of hashrate-based double spending. http://arxiv.org/abs/1402.2009, 2014. Accessed: 2016-03-09.
[RSW96] Ronald L Rivest, Adi Shamir, and David A Wagner. Time-lock puzzles and timed-release crypto. 1996.
[Sch90] Fred B Schneider. Implementing fault-tolerant services using the state machine approach: A tutorial. volume 22, pages 299–319. ACM, 1990.
[SLZ16] Yonatan Sompolinsky, Yoad Lewenberg, and Aviv Zohar. Spectre: A fast and scalable cryptocurrency protocol. Cryptology ePrint Archive, Report 2016/1159, 2016. Accessed: 2017-02-20.
[SSZ15] Ayelet Sapirshtein, Yonatan Sompolinsky, and Aviv Zohar. Optimal selfish mining strategies in bitcoin. http://arxiv.org/pdf/1507.06183.pdf, 2015. Accessed: 2016-08-22.
[SW16] David Stolz and Roger Wattenhofer. Byzantine agreement with median validity. In LIPIcs-Leibniz International Proceedings in Informatics, volume 46. Schloss Dagstuhl-Leibniz-Zentrum fuer Informatik, 2016.
[Swa15] Tim Swanson. Consensus-as-a-service: a brief report on the emergence of permissioned, distributed ledger systems. http://www.ofnumbers.com/wp-content/uploads/2015/04/Permissioned-distributed-ledgers.pdf, Apr 2015. Accessed: 2017-10-03.
[SZ13] Yonatan Sompolinsky and Aviv Zohar. Accelerating bitcoin’s transaction processing. fast money grows on trees, not chains, 2013.
[SZ16] Yonatan Sompolinsky and Aviv Zohar. Bitcoin’s security model revisited. http://arxiv.org/pdf/1605.09193, 2016. Accessed: 2016-07-04.
[Sza14] Nick Szabo. The dawn of trustworthy computing. http://unenumerated.blogspot.co.at/2014/12/the-dawn-of-trustworthy-computing.html, 2014. Accessed: 2017-12-01.
[TS16] Florian Tschorsch and Bjorn Scheuermann. Bitcoin and ¨ beyond: A technical survey on decentralized digital currencies. In IEEE Communications Surveys Tutorials, volume PP, pages 1–1, 2016.
[VCB+13] Giuliana Santos Veronese, Miguel Correia, Alysson Neves Bessani, Lau Cheuk Lung, and Paulo Verissimo. Efficient byzantine fault-tolerance. volume 62, pages 16–30. IEEE, 2013.
[Ver03] Paulo Ver´ıssimo. Uncertainty and predictability: Can they be reconciled? In Future Directions in Distributed Computing, pages 108–113. Springer, 2003.
[Vuk15] Marko Vukolic. The quest for scalable blockchain fabric: ´ Proof-of-work vs. bft replication. In International Workshop on Open Problems in Network Security, pages 112–125. Springer, 2015.
[Vuk16] Marko Vukolic. Eventually returning to strong consistency. https://pdfs.semanticscholar.org/a6a1/b70305b27c556aac779fb65429db9c2e1ef2.pdf, 2016. Accessed: 2016-08-10.
[XWS+17] Xiwei Xu, Ingo Weber, Mark Staples, Liming Zhu, Jan Bosch, Len Bass, Cesare Pautasso, and Paul Rimba. A taxonomy of blockchain-based systems for architecture design. In Software Architecture (ICSA), 2017 IEEE International Conference on , pages 243–252. IEEE, 2017.
[YHKC+16] Jesse Yli-Huumo, Deokyoon Ko, Sujin Choi, Sooyong Park, and Kari Smolander. Where is current research on blockchain technology? – a systematic review. volume 11, page e0163477. Public Library of Science, 2016.
[ZP17] Ren Zhang and Bart Preneel. On the necessity of a prescribed block validity consensus: Analyzing bitcoin unlimited mining protocol. http://eprint.iacr.org/2017/686, 2017. Accessed: 2017-07-20.
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An Analysis of Attacks on Blockchain Consensus

arXiv:1610.07985
Date: 2016-11-20
Author(s): George Bissias, Brian Neil Levine, A. Pinar Ozisik, Gavin Andresen

Link to Paper


Abstract
We present and validate a novel mathematical model of the blockchain mining process and use it to conduct an economic evaluation of the double-spend attack, which is fundamental to all blockchain systems. Our analysis focuses on the value of transactions that can be secured under a conventional double-spend attack, both with and without a concurrent eclipse attack. Our model quantifies the importance of several factors that determine the attack's success, including confirmation depth, attacker mining power, and any confirmation deadline set by the merchant. In general, the security of a transaction against a double-spend attack increases roughly logarithmically with the depth of the block, made easier by the increasing sum of coin turned-over (between individuals) in the blocks, but more difficult by the increasing proof of work required. In recent blockchain data, we observed a median block turnover value of 6 BTC. Based on this value, a merchant requiring a single confirmation is protected against only attackers that can increase the current mining power by 1% or less. However, similar analysis shows that a merchant that requires a much longer 72 confirmations (~12 hours) will eliminate all potential profit for any double-spend attacker adding mining power less than 40% of the current mining power.

References
  1. Back, A., Corallo, M., Dashjr, L., Mark, F., Maxwell, G., Miller, A., Poelstra, A., Timón, J., Wuille, P.: Enabling Blockchain Innovations with Pegged Sidechains. http://www.opensciencereview.com/papers/123/enablingblockchain-innovations-with-pegged-sidechains (October 2014)
  2. Bissias, G., Ozisik, A.P., Levine, B.N., Liberatore, M.: Sybil-Resistant Mixing for Bitcoin. In: Proc. ACM Workshop on Privacy in the Electronic Society (November 2014), http://forensics.umass.edu/pubs/bissias.wpes.2014.pdf
  3. Confirmation. https://en.bitcoin.it/wiki/Confirmation (February 2015)
  4. Bonneau, J., Miller, A., Clark, J., Narayanan, A., Kroll, J., Felten, E.: Sok: Research perspectives and challenges for bitcoin and cryptocurrencies. In: IEEE S&P. pp. 104–121 (May 2015), http://doi.org/10.1109/SP.2015.14
  5. Bonneau, J.: How long does it take for a bitcoin transaction to be confirmed? https://coincenter.org/2015/11/what-does-it-mean-for-a-bitcoin-transactionto-be-confirmed/ (November 2015)
  6. Croman, K., et al.: On Scaling Decentralized Blockchains . In: Workshop on Bitcoin and Blockchain Research (Feb 2016)
  7. Douceur, J.: The Sybil Attack. In: Proc. Intl Wkshp on Peer-to-Peer Systems (IPTPS) (Mar 2002)
  8. Ethereum Homestead Documentation. http://ethdocs.org/en/latest/
  9. Eyal, I., Sirer, E.G.: Majority Is Not Enough: Bitcoin Mining Is Vulnerable. Financial Cryptography pp. 436–454 (2014), http://doi.org/10.1007/978-3-662-45472-5_28
  10. Fischer, M., Lynch, N., Paterson, M.: Impossibility of distributed consensus with one faulty process. JACM 32(2), 374–382 (1985)
  11. Gervais, A., O. Karame, G., Wust, K., Glykantzis, V., Ritzdorf, H., Capkun, S.: On the Security and Performance of Proof of Work Blockchains. https://eprint.iacr.org/2016/555 (2016)
  12. Heilman, E., Alshenibr, L., Baldimtsi, F., Scafuro, A., Goldberg, S.: Tumblebit: An untrusted bitcoin-compatible anonymous payment hub. Cryptology ePrint Archive, Report 2016/575 (2016), http://eprint.iacr.org/2016/575
  13. Heilman, E., Kendler, A., Zohar, A., Goldberg, S.: Eclipse Attacks on Bitcoin’s Peer-to-peer Network. In: USENIX Security (2015)
  14. Litecoin. http://litecoin.org/
  15. Meiklejohn, S., Pomarole, M., Jordan, G., Levchenko, K., McCoy, D., Voelker, G., Savage, S.: A Fistful of Bitcoins: Characterizing Payments Among Men with No Names. In: Proc. ACM IMC. pp. 127–140 (2013), http://doi.acm.org/10.1145/2504730.2504747
  16. Nakamoto, S.: Bitcoin: A Peer-to-Peer Electronic Cash System. https://bitcoin.org/bitcoin.pdf (May 2009)
  17. Pagnia, H., Vogt, H., Gaertner, F.: Fair Exchange. The Computer Journal, vol. 46, num. 1, p. 55, 2003. 46(1), 55–78 (2003)
  18. Poon, J., Dryja, T.: The Bitcoin Lightning Network: Scalable Off-Chain Instant Payments. http://www.lightning.network/lightning-network-paper.pdf (November 2015)
  19. Ron, D., Shamir, A.: Quantitative analysis of the full bitcoin transaction graph. In: Proc. Financial Crypto. pp. 6–24 (Apr 2013), http://doi.org/10.1007/978-3-642-39884-1_2
  20. Rosenfeld, M.: Analysis of hashrate-based double-spending. https://bitcoil.co.il/Doublespend.pdf (December 2012)
  21. Sapirshtein, A., Sompolinsky, Y., Zohar, A.: Optimal Selfish Mining Strategies in Bitcoin. https://arxiv.org/pdf/1507.06183.pdf (July 2015)
  22. Sasson, E.B., Chiesa, A., Garman, C., Green, M., Miers, I., Tromer, E., Virza, M.: Zerocash: Decentralized anonymous payments from bitcoin. In: IEEE S&P. pp. 459–474 (2014), http://dx.doi.org/10.1109/SP.2014.36
  23. Sompolinsky, Y., Zohar, A.: Secure high-rate transaction processing in Bitcoin. Financial Cryptography and Data Security (2015), http://doi.org/10.1007/978-3-662-47854-7_32
  24. Sompolinsky, Y., Zohar, A.: Bitcoin’s Security Model Revisited. https://arxiv.org/abs/1605.09193 (May 2016)
  25. Tschorsch, F., Scheuermann, B.: Bitcoin and beyond: A technical survey on decentralized digital currencies. IEEE Communications Surveys Tutorials PP(99), 1–1 (2016)
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Evolutionary Game for Mining Pool Selection in Blockchain Networks

arXiv:1712.02027
Date: 2017-12-29
Author(s): Xiaojun Liu, Wenbo Wang, Dusit Niyato, Narisa Zhao, Ping Wang

Link to Paper


Abstract
In blockchain networks adopting the proof-of-work schemes, the monetary incentive is introduced by the Nakamoto consensus protocol to guide the behaviors of the full nodes (i.e., block miners) in the process of maintaining the consensus about the blockchain state. The block miners have to devote their computation power measured in hash rate in a crypto-puzzle solving competition to win the reward of publishing (a.k.a., mining) new blocks. Due to the exponentially increasing difficulty of the crypto-puzzle, individual block miners tends to join mining pools, i.e., the coalitions of miners, in order to reduce the income variance and earn stable profits. In this paper, we study the dynamics of mining pool selection in a blockchain network, where mining pools may choose arbitrary block mining strategies. We identify the hash rate and the block propagation delay as two major factors determining the outcomes of mining competition, and then model the strategy evolution of the individual miners as an evolutionary game. We provide the theoretical analysis of the evolutionary stability for the pool selection dynamics in a case study of two mining pools. The numerical simulations provide the evidence to support our theoretical discoveries as well as demonstrating the stability in the evolution of miners' strategies in a general case.

References
[1] S. Nakamoto, “Bitcoin: A peer-to-peer electronic cash system,” Selfpublished Paper, May 2008.
[2] F. Tschorsch and B. Scheuermann, “Bitcoin and beyond: A technical survey on decentralized digital currencies,” IEEE Communications Surveys Tutorials, vol. 18, no. 3, pp. 2084–2123, third quarter 2016.
[3] J. Garay, A. Kiayias, and N. Leonardos, “The bitcoin backbone protocol: Analysis and applications,” in 34th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Sofia, Bulgaria, Apr. 2015, pp. 281–310.
[4] P. R. Rizun, “A transaction fee market exists without a block size limit,” Self-published Paper, Aug. 2015.
[5] N. Houy, “The bitcoin mining game,” Ledger Journal, vol. 1, no. 13, pp. 53 – 68, 2016.
[6] B. A. Fisch, R. Pass, and A. Shelat, “Socially optimal mining pools,” arXiv preprint arXiv:1703.03846, 2017.
[7] J. Hofbauer and K. Sigmund, “Evolutionary game dynamics,” Bulletin of the American Mathematical Society, vol. 40, no. 4, pp. 479–519, 2003.
[8] J. Hofbauer and W. H. Sandholm, “Stable games and their dynamics,” Journal of Economic Theory, vol. 144, no. 4, pp. 1665 – 1693.e4, 2009.
[9] J. W. Weibull, Evolutionary game theory. MIT press, 1997.
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Bitcoin-NG: A Scalable Blockchain Protocol

arXiv:1510.02037
Date: 2015-11-11
Author(s): Ittay Eyal, Adem Efe Gencer, Emin Gun Sirer, Robbert van Renesse

Link to Paper


Abstract
Cryptocurrencies, based on and led by Bitcoin, have shown promise as infrastructure for pseudonymous online payments, cheap remittance, trustless digital asset exchange, and smart contracts. However, Bitcoin-derived blockchain protocols have inherent scalability limits that trade-off between throughput and latency and withhold the realization of this potential.This paper presents Bitcoin-NG, a new blockchain protocol designed to scale. Based on Bitcoin's blockchain protocol, Bitcoin-NG is Byzantine fault tolerant, is robust to extreme churn, and shares the same trust model obviating qualitative changes to the ecosystem.In addition to Bitcoin-NG, we introduce several novel metrics of interest in quantifying the security and efficiency of Bitcoin-like blockchain protocols. We implement Bitcoin-NG and perform large-scale experiments at 15% the size of the operational Bitcoin system, using unchanged clients of both protocols. These experiments demonstrate that Bitcoin-NG scales optimally, with bandwidth limited only by the capacity of the individual nodes and latency limited only by the propagation time of the network.

References
[1] Andresen, G. O(1) block propagation. https://gist.github.com/gavinandresen/#file-blockpropagation-md, retrieved July. 2015.
[2] Aspnes, J. Randomized protocols for asynchronous consensus. Distributed Computing 16, 2-3 (2003), 165–175.
[3] Back, A., Corallo, M., Dashjr, L., Friedenbach, M., Maxwell, G., Miller, A., Poelstra, A., Timn, J., and Wuille, P. Enabling blockchain innovations with pegged sidechains. http://cs.umd.edu/projects/coinscope/coinscope.pdf, 2014.
[4] Bamert, T., Decker, C., Elsen, L., Wattenhofer, R., and Welten, S. Have a snack, pay with Bitcoins. In Peer-to-Peer Computing (P2P), 2013 IEEE Thirteenth International Conference on (2013), IEEE, pp. 1–5.
[5] Bellare, M., and Rogaway, P. Random oracles are practical: A paradigm for designing efficient protocols. In Proceedings of the 1st ACM conference on Computer and communications security (1993), ACM, pp. 62–73.
[6] Bitcoin community. Bitcoin source. https://github.com/bitcoin/bitcoin, retrieved Mar. 2015.
[7] Bitcoin community. Protocol rules. https://en.bitcoin.it/wiki/Protocol_rules, retrieved Sep. 2013.
[8] Bitcoin community. Protocol specification. https://en.bitcoin.it/wiki/Protocol_specification, retrieved Sep. 2013.
[9] BlockTrail. BlockTrail API. https://www.blocktrail.com/api/docs#api_data, retrieved Sep. 2015.
[10] Bonneau, J., Miller, A., Clark, J., Narayanan, A., Kroll, J. A., and Felten, E. W. Research perspectives on Bitcoin and second-generation cryptocurrencies. In Symposium on Security and Privacy (San Jose, CA, USA, 2015), IEEE.
[11] Buterin, V. Slasher: A punitive proof-of-stake algorithm. https://blog.ethereum.org/2014/01/15/slasher-a-punitive-proof-of-stake-algorithm/, January 2015.
[12] CNNMoney Staff. The Ashley Madison hack...in 2 minutes. http://money.cnn.com/2015/08/24/technology/ashley-madison-hack-in-2-minutes/, retrieved Sep. 2015.
[13] CoinDesk. Bitcoin venture capital. http://www.coindesk.com/bitcoin-venture-capital/, retrieved Sep. 2015.
[14] Colored Coins Project. Colored Coins. http://coloredcoins.org/, retrieved Sep. 2015.
[15] Corallo, M. High-speed Bitcoin relay network. http://sourceforge.net/p/bitcoin/mailman/message/31604935/, November 2013.
[16] Decker, C., and Wattenhofer, R. Information propagation in the Bitcoin network. In IEEE P2P (Trento, Italy, 2013).
[17] Decker, C., and Wattenhofer, R. A fast and scalable payment network with Bitcoin Duplex Micropayment Channels. In Stabilization, Safety, and Security of Distributed Systems - 17th International Symposium, SSS 2015, Edmonton, AB, Canada, August 18-21, 2015, Proceedings (2015), Springer, pp. 3–18.
[18] Dwork, C., Lynch, N. A., and Stockmeyer, L. J. Consensus in the presence of partial synchrony. J. ACM 35, 2 (1988), 288–323.
[19] Eyal, I., Birman, K., and van Renesse, R. Cache serializability: Reducing inconsistency in edge transactions. In 35th IEEE International Conference on Distributed Computing Systems, ICDCS 2015, Columbus, OH, USA, June 29 - July 2, 2015 (2015), pp. 686–695.
[20] Eyal, I., and Sirer, E. G. Bitcoin is broken. http://hackingdistributed.com/2013/11/04/bitcoin-is-broken/, 2013.
[21] Eyal, I., and Sirer, E. G. Majority is not enough: Bitcoin mining is vulnerable. In Financial Cryptography and Data Security (Barbados, 2014).
[22] Garay, J. A., Kiayias, A., and Leonardos, N. The Bitcoin backbone protocol: Analysis and applications. In Advances in Cryptology - EUROCRYPT 2015 - 34th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Sofia, Bulgaria, April 26-30, 2015, Proceedings, Part II (2015), pp. 281–310.
[23] Garcia-Molina, H. Elections in a distributed computing system. Computers, IEEE Transactions on 100, 1 (1982), 48–59.
[24] Hearn, M., and Spilman, J. Rapidly-adjusted (micro)payments to a pre-determined party. https://en.bitcoin.it/wiki/Contract, retrieved Sep. 2015.
[25] Heilman, E., Kendler, A., Zohar, A., and Goldberg, S. Eclipse attacks on Bitcoin’s peerto-peer network. In 24th USENIX Security Symposium, USENIX Security 15, Washington, D.C., USA, August 12-14, 2015. (2015), pp. 129–144.
[26] Kosba, A., Miller, A., Shi, E., Wen, Z., and Papamanthou, C. Hawk: The blockchain model of cryptography and privacy-preserving smart contracts. Cryptology ePrint Archive, Report 2015/675, 2015. http://eprint.iacr.org/.
[27] Kroll, J. A., Davey, I. C., and Felten, E. W. The economics of Bitcoin mining or, Bitcoin in the presence of adversaries. In Workshop on the Economics of Information Security (2013).
[28] Lamport, L. Using time instead of timeout for fault-tolerant distributed systems. ACM Transactions on Programming Languages and Systems 6, 2 (Apr. 1984), 254–280.
[29] Le Lann, G. Distributed systems-towards a formal approach. In IFIP Congress (1977), vol. 7, Toronto, pp. 155–160.
[30] Lewenberg, Y., Sompolinsky, Y., and Zohar, A. Inclusive block chain protocols. In Financial Cryptography (Puerto Rico, 2015).
[31] Litecoin Project. Litecoin, open source P2P digital currency. https://litecoin.org, retrieved Nov. 2014.
[32] Meiklejohn, S., Pomarole, M., Jordan, G., Levchenko, K., McCoy, D., Voelker, G. M., and Savage, S. A fistful of bitcoins: characterizing payments among men with no names. In Proceedings of the 2013 Internet Measurement Conference, IMC 2013, Barcelona, Spain, October 23-25, 2013 (2013), pp. 127–140.
[33] Miller, A., and Jansen, R. Shadow-Bitcoin: Scalable simulation via direct execution of multithreaded applications. IACR Cryptology ePrint Archive 2015 (2015), 469.
[34] Miller, A., and Jr., L. J. J. Anonymous Byzantine consensus from moderately-hard puzzles: A model for Bitcoin. https://socrates1024.s3.amazonaws.com/consensus.pdf, 2009.
[35] Miller, A., Litton, J., Pachulski, A., Gupta, N., Levin, D., Spring, N., and Bhattacharjee, B. Preprint: Discovering Bitcoins public topology and influential nodes. http://cs.umd.edu/projects/coinscope/coinscope.pdf, 2015.
[36] Moraru, I., Andersen, D. G., and Kaminsky, M. Egalitarian Paxos. In ACM Symposium on Operating Systems Principles (2012).
[37] Nakamoto, S. Bitcoin: A peer-to-peer electronic cash system. http://www.bitcoin.org/ bitcoin.pdf, 2008.
[38] Nayak, K., Kumar, S., Miller, A., and Shi, E. Stubborn mining: Generalizing selfish mining and combining with an eclipse attack. IACR Cryptology ePrint Archive 2015 (2015), 796.
[39] Pazmino, J. E., and da Silva Rodrigues, C. K. ˜ Simply dividing a Bitcoin network node may reduce transaction verification time. The SIJ Transactions on Computer Networks and Communication Engineering (CNCE) 3, 2 (February 2015), 17–21.
[40] Pease, M. C., Shostak, R. E., and Lamport, L. Reaching agreement in the presence of faults. J. ACM 27, 2 (1980), 228–234.
[41] Peck, M. E. Adam Back says the Bitcoin fork is a coup. http://spectrum.ieee.org/tech-talk/computing/networks/the-bitcoin-for-is-a-coup, Aug 2015.
[42] Poon, J., and Dryja, T. The Bitcoin Lightning Network. http://lightning.network/lightning-network.pdf, February 2015. Draft 0.5.
[43] Sapirshtein, A., Sompolinsky, Y., and Zohar, A. Optimal selfish mining strategies in Bitcoin. CoRR abs/1507.06183 (2015).
[44] Schneider, F. B. Implementing fault-tolerant services using the state machine approach: A tutorial. ACM Computing Surveys 22, 4 (Dec. 1990), 299–319.
[45] Sompolinsky, Y., and Zohar, A. Accelerating Bitcoin’s transaction processing. fast money grows on trees, not chains. In Financial Cryptography (Puerto Rico, 2015).
[46] Sompolinsky, Y., and Zohar, A. Secure high-rate transaction processing in Bitcoin. In Financial Cryptography and Data Security - 19th International Conference, FC 2015, San Juan, Puerto Rico, January 26-30, 2015, Revised Selected Papers (2015), pp. 507–527.
[47] Stathakopoulou, C. A faster Bitcoin network. Tech. rep., ETH, Z¨urich, January 2015. Semester Thesis, supervised by C. Decker and R. Wattenhofer.
[48] Swanson, E. Bitcoin mining calculator. http://www.alloscomp.com/bitcoin/calculator, retrieved Sep. 2013.
[49] The Ethereum community. Ethereum white paper. https://github.com/ethereum/wiki/wiki/White-Paper, retrieved July. 2015.
[50] Wikipedia. List of cryptocurrencies. https://en.wikipedia.org/wiki/List_of_cryptocurrencies, retrieved Oct. 2013.
submitted by dj-gutz to myrXiv [link] [comments]

Here's a list of 158 free online programming/CS courses (MOOCs) with feedback(i.e. exams/homeworks/assignments) that you can start this month (September 2015)

This is not the complete list of MOOCs starting in September 2015, just the ones relevant to this community. The complete list of courses starting in September 2015 can be found over at Class Central. I maintain a much bigger list of these courses over at Class Central
BEGINNER(35)
Course Name Start Date Length (in weeks) Provider Rating
BJC.1x: The Beauty and Joy of Computing, Part 1 8th Sep, 2015 NA edX ☆☆☆☆☆
HTML, CSS and JavaScript Sep, 2015 NA Coursera ☆☆☆☆☆
Data Analysis and Statistical Inference 14th Sep, 2015 10 Coursera ★★★★★ (22 reviews)
Usable Security 14th Sep, 2015 6 Coursera ★★★★☆ (3 reviews)
Programming and the Web for Beginners Sep, 2015 NA Coursera ☆☆☆☆☆
Ruby on Rails: An Introduction Sep, 2015 NA Coursera ☆☆☆☆☆
Introduction to HTML5 Sep, 2015 NA Coursera ☆☆☆☆☆
Getting Started with Python Sep, 2015 NA Coursera ☆☆☆☆☆
DEV208x: Introduction to jQuery 15th Sep, 2015 3 edX ☆☆☆☆☆
Louv1.1x: Paradigms of Computer Programming – Fundamentals 21st Sep, 2015 5 edX ☆☆☆☆☆
CAMS.2x: Computing: Art, Magic, Science 22nd Sep, 2015 7 edX ☆☆☆☆☆
CODAPPS: Coding mobile apps for entrepreneurs Sep, 2015 NA Coursera ☆☆☆☆☆
Intro to Computer Science Self paced 12 Udacity ★★★★★ (47 reviews)
Intro to Java Programming Self paced 16 Udacity ★★★☆☆ (10 reviews)
Mobile Web Development Self paced 6 Udacity ☆☆☆☆☆
DB: Introduction to Databases Self paced 11 Stanford OpenEdx ★★★★★ (5 reviews)
Make Your Own 2048 Self paced NA Udacity ★★★★☆ (3 reviews)
Programming Foundations with Python Self paced 6 Udacity ★★★★☆ (2 reviews)
Intro to HTML and CSS Self paced 3 Udacity ★★★★☆ (10 reviews)
JavaScript Basics Self paced 3 Udacity ★★★★☆ (7 reviews)
How to Use Git and GitHub Self paced 3 Udacity ★★★★★ (15 reviews)
CS50x: Introduction to Computer Science Self paced NA edX ★★★★★ (33 reviews)
Intro to Relational Databases Self paced 4 Udacity ★★★☆☆ (1 review)
Networking: Introduction to Computer Networking Self paced 11 Stanford OpenEdx ★★★★★ (5 reviews)
CS101: Computer Science 101 Self paced 6 Stanford OpenEdx ★★★☆☆ (5 reviews)
CS002x: Programming in Scratch Self paced 6 edX ★★★★☆ (3 reviews)
CS001x: MyCS: Computer Science for Beginners Self paced 6 edX ★★★☆☆ (1 review)
DEV203x: Introduction to Bootstrap – A Tutorial Self paced 3 edX ★★☆☆☆ (5 reviews)
LFS101x.2: Introduction to Linux Self paced 8 edX ★★★★☆ (16 reviews)
CS005x: CS For All: Introduction to Computer Science and Python Programming Self paced 14 edX ★★★★★ (2 reviews)
CS101.1x: Introduction to Computer Programming, Part 1 Self paced 9 edX ★★☆☆☆ (9 reviews)
COMP102.1x: Introduction to Java Programming – Part 1 Self paced 5 edX ★★★★☆ (3 reviews)
Learn Swift Programming Syntax Self paced 3 Udacity ☆☆☆☆☆
Linux Command Line Basics Self paced 1 Udacity ☆☆☆☆☆
Computer Science 101 Self paced NA Coursera ★★★★☆ (11 reviews)
INTERMEDIATE(97)
Course Name Start Date Length (in weeks) Provider Rating
EX101x: Data Analysis: Take It to the MAX() 1st Sep, 2015 8 edX ★★★☆☆ (10 reviews)
Python Data Structures Sep, 2015 NA Coursera ☆☆☆☆☆
Programming Mobile Applications for Android Handheld Systems: Part 1 2nd Sep, 2015 4 Coursera ★★★★☆ (27 reviews)
Programming Mobile Applications for Android Handheld Systems: Part 2 2nd Sep, 2015 4 Coursera ★★★★★ (7 reviews)
Algorithms, Part I 4th Sep, 2015 6 Coursera ★★★★☆ (24 reviews)
Algorithmic Thinking (Part 1) 5th Sep, 2015 4 Coursera ★★★☆☆ (3 reviews)
Statistical Inference 7th Sep, 2015 4 Coursera ★★☆☆☆ (9 reviews)
Regression Models 7th Sep, 2015 4 Coursera ★★★☆☆ (8 reviews)
Practical Machine Learning 7th Sep, 2015 4 Coursera ★★★☆☆ (10 reviews)
Developing Data Products 7th Sep, 2015 4 Coursera ★★★★☆ (4 reviews)
Introduction to Genomic Technologies 7th Sep, 2015 4 Coursera ★★★☆☆ (6 reviews)
Bioconductor for Genomic Data Science 7th Sep, 2015 4 Coursera ☆☆☆☆☆
Python for Genomic Data Science 7th Sep, 2015 4 Coursera ★★★★☆ (4 reviews)
Statistics for Genomic Data Science 7th Sep, 2015 4 Coursera ☆☆☆☆☆
Concepts in Game Development 7th Sep, 2015 4 Open2Study ★★★★☆ (14 reviews)
The Data Scientist’s Toolbox 7th Sep, 2015 4 Coursera ★★★☆☆ (79 reviews)
R Programming 7th Sep, 2015 4 Coursera ★★★☆☆ (128 reviews)
Getting and Cleaning Data 7th Sep, 2015 4 Coursera ★★★☆☆ (23 reviews)
Exploratory Data Analysis 7th Sep, 2015 4 Coursera ★★★★☆ (13 reviews)
Reproducible Research 7th Sep, 2015 4 Coursera ★★★★☆ (10 reviews)
SPD2x: Systematic Program Design - Part 2: Arbitrary Sized Data 8th Sep, 2015 5 edX ☆☆☆☆☆
Analysis of Algorithms 11th Sep, 2015 6 Coursera ★★★★☆ (1 review)
Automata 12th Sep, 2015 6 Coursera ★★★★☆ (7 reviews)
Mining Massive Datasets 12th Sep, 2015 7 Coursera ★★★★★ (6 reviews)
Software Security 14th Sep, 2015 6 Coursera ★★★★★ (11 reviews)
Cryptography 14th Sep, 2015 7 Coursera ★★★★★ (4 reviews)
Responsive Website Basics: Code with HTML, CSS, and JavaScript Sep, 2015 NA Coursera ☆☆☆☆☆
Introduction To Swift Programming Sep, 2015 NA Coursera ☆☆☆☆☆
Foundations of Objective-C App Development Sep, 2015 NA Coursera ☆☆☆☆☆
Database Management Essentials Sep, 2015 NA Coursera ☆☆☆☆☆
Introduction to Big Data Sep, 2015 NA Coursera ☆☆☆☆☆
Data Management and Visualization Sep, 2015 NA Coursera ☆☆☆☆☆
Introduction to Software Product Management Sep, 2015 NA Coursera ☆☆☆☆☆
Object Oriented Programming in Java Sep, 2015 NA Coursera ☆☆☆☆☆
Design of Computer Programs Self paced 8 Udacity ★★★★☆ (9 reviews)
Web Development Self paced 12 Udacity ★★★★★ (16 reviews)
Programming Languages Self paced 8 Udacity ★★★☆☆ (7 reviews)
Intro to Algorithms Self paced 16 Udacity ★☆☆☆☆ (1 review)
Software Testing Self paced 4 Udacity ★★★★☆ (5 reviews)
Software Debugging Self paced 8 Udacity ★★★★☆ (2 reviews)
Intro to Theoretical Computer Science Self paced 8 Udacity ★★★★★ (1 review)
Intro to Artificial Intelligence Self paced 16 Udacity ★★★★☆ (4 reviews)
HTML5 Game Development Self paced 8 Udacity ★★★☆☆ (4 reviews)
Learning from Data (Introductory Machine Learning course) Self paced 10 Others ★★★★☆ (2 reviews)
Intro to Hadoop and MapReduce Self paced 4 Udacity ★★★★☆ (8 reviews)
CS 8802, Artificial Intelligence for Robotics: Programming a Robotic Car Self paced NA Udacity ★★★★★ (1 review)
Intro to Data Science Self paced 8 Udacity ★★★★☆ (7 reviews)
Data Wrangling with MongoDB Self paced 8 Udacity ★★★★☆ (3 reviews)
Data Analysis with R Self paced 8 Udacity ★★★★★ (11 reviews)
Parallel Programming Concepts Self paced NA openHPI ★★★★☆ (3 reviews)
Website Performance Optimization Self paced 1 Udacity ★★★★☆ (2 reviews)
UX Design for Mobile Developers Self paced 6 Udacity ★★★★☆ (1 review)
Developing Scalable Apps in Java Self paced 8 Udacity ★★★★☆ (1 review)
Developing Android Apps Self paced 10 Udacity ★★★★★ (2 reviews)
Software Development Process Self paced 12 Udacity ☆☆☆☆☆
Computer Networking Self paced 12 Udacity ★★★★★ (2 reviews)
Practical Numerical Methods with Python Self paced 17 Others ★★★★★ (2 reviews)
Object-Oriented JavaScript Self paced 5 Udacity ★★★★★ (6 reviews)
Intro to AJAX Self paced 2 Udacity ★★★★★ (1 review)
Data Visualization and D3.js Self paced 7 Udacity ★★★☆☆ (1 review)
HTML5 Canvas Self paced 2 Udacity ★★★★☆ (2 reviews)
Intro to iOS App Development with Swift Self paced 4 Udacity ★★★★★ (4 reviews)
Intro to jQuery Self paced NA Udacity ★★★★☆ (2 reviews)
Intro to Machine Learning Self paced 10 Udacity ★★★★☆ (5 reviews)
Full Stack Foundations Self paced 3 Udacity ☆☆☆☆☆
Responsive Web Design Fundamentals Self paced 2 Udacity ★★★★☆ (3 reviews)
Health Informatics in the Cloud Self paced 5 Udacity ☆☆☆☆☆
JavaScript Testing Self paced 2 Udacity ★★★★★ (1 review)
UIKit Fundamentals Self paced 8 Udacity ☆☆☆☆☆
LPL: Language, Proof and Logic Self paced 15 Stanford OpenEdx ☆☆☆☆☆
Responsive Images Self paced 2 Udacity ★★★★☆ (2 reviews)
Machine Learning Self paced NA Coursera ★★★★★ (100 reviews)
iOS Networking with Swift Self paced 12 Udacity ☆☆☆☆☆
Authentication & Authorization: OAuth Self paced 2 Udacity ★★★★☆ (2 reviews)
Browser Rendering Optimization Self paced 4 Udacity ★★★★☆ (1 review)
Developing Scalable Apps in Python Self paced 6 Udacity ★★★★☆ (1 review)
iOS Persistence and Core Data Self paced 8 Udacity ☆☆☆☆☆
How to Make an iOS App Self paced 12 Udacity ☆☆☆☆☆
Android Performance Self paced 4 Udacity ☆☆☆☆☆
Android Development for Beginners Self paced 4 Udacity ★★★★☆ (5 reviews)
Advanced Android App Development Self paced 6 Udacity ☆☆☆☆☆
Android Design for Developers Self paced 4 Udacity ☆☆☆☆☆
Android Ubiquitous Computing Self paced 4 Udacity ☆☆☆☆☆
Google Play Services Self paced 8 Udacity ☆☆☆☆☆
Gradle for Android and Java Self paced 6 Udacity ★★★★★ (1 review)
DEV201x: Introduction to TypeScript Self paced 6 edX ☆☆☆☆☆
DEV202.1x: Building Cloud Apps with Microsoft Azure – Part 1 Self paced 4 edX ★★★☆☆ (1 review)
DEV204x: Programming with C# Self paced 6 edX ★★★★☆ (5 reviews)
AMRx: Autonomous Mobile Robots Self paced NA edX ★★★☆☆ (3 reviews)
Xcode Debugging Self paced 3 Udacity ☆☆☆☆☆
PH525.1x: Statistics and R for the Life Sciences Self paced 4 edX ★★★★☆ (6 reviews)
KIexploRx: Explore Statistics with R Self paced NA edX ★★★★☆ (7 reviews)
Intro to DevOps Self paced 3 Udacity ☆☆☆☆☆
Configuring Linux Web Servers Self paced 1 Udacity ☆☆☆☆☆
Learn Backbone.js Self paced 2 Udacity ☆☆☆☆☆
Android TV and Google Cast Development Self paced 1 Udacity ☆☆☆☆☆
JavaScript Design Patterns Self paced 6 Udacity ★★★★★ (1 review)
ADVANCED(26)*
Course Name Start Date Length (in weeks) Provider Rating
Bitcoin and Cryptocurrency Technologies 4th Sep, 2015 7 Coursera ☆☆☆☆☆
Genomic Data Science with Galaxy 7th Sep, 2015 4 Coursera ★★☆☆☆ (4 reviews)
Command Line Tools for Genomic Data Science 7th Sep, 2015 4 Coursera ☆☆☆☆☆
Algorithms for DNA Sequencing 7th Sep, 2015 4 Coursera ★★★★★ (8 reviews)
Hardware Security 14th Sep, 2015 6 Coursera ★★★☆☆ (6 reviews)
Big Data Science with the BD2K-LINCS Data Coordination and Integration Center 15th Sep, 2015 7 Coursera ★★★☆☆ (1 review)
Machine Learning Foundations: A Case Study Approach Sep, 2015 NA Coursera ☆☆☆☆☆
DAT203x: Data Science and Machine Learning Essentials 24th Sep, 2015 5 edX ☆☆☆☆☆
Machine Learning Self paced NA Udacity ★★★★★ (1 review)
Artificial Intelligence for Robotics Self paced 8 Udacity ★★★★★ (11 reviews)
Applied Cryptography Self paced 8 Udacity ★★★★☆ (2 reviews)
Intro to Parallel Programming Self paced 12 Udacity ★★★★☆ (2 reviews)
Interactive 3D Graphics Self paced 8 Udacity ★★★★★ (2 reviews)
Functional Hardware Verification Self paced 8 Udacity ★★★★★ (1 review)
Machine Learning 1—Supervised Learning Self paced NA Udacity ★★★★☆ (1 review)
Machine Learning 2—Unsupervised Learning Self paced NA Udacity ★★★★☆ (1 review)
Machine Learning 3—Reinforcement Learning Self paced 4 Udacity ★★★☆☆ (2 reviews)
In-Memory Data Management In a Nutshell Self paced NA openSAP ★★☆☆☆ (1 review)
Real-Time Analytics with Apache Storm Self paced 2 Udacity ★★★★☆ (1 review)
Model Building and Validation Self paced 8 Udacity ★★★☆☆ (3 reviews)
Advanced Operating Systems Self paced 5 Udacity ★★★★★ (1 review)
High Performance Computer Architecture Self paced NA Udacity ☆☆☆☆☆
Computability, Complexity & Algorithms Self paced NA Udacity ☆☆☆☆☆
Knowledge-Based AI: Cognitive Systems Self paced 7 Udacity ☆☆☆☆☆
Introduction to Recommender Systems Self paced NA Coursera ★★★★☆ (10 reviews)
Machine Learning Self paced 16 Udacity ☆☆☆☆☆
submitted by dhawal to learnprogramming [link] [comments]

Estimation of Miner Hash Rates and Consensus on Blockchains

arXiv:1707.00082
Date: 2017-07-01
Author(s): A. Pinar Ozisik, George Bissias, Brian Levine

Link to Paper


Abstract
We make several contributions that quantify the real-time hash rate and therefore the consensus of a blockchain. We show that by using only the hash value of blocks, we can estimate and measure the hash rate of all miners or individual miners, with quanti able accuracy. We apply our techniques to the Ethereum and Bitcoin blockchains; our solution applies to any proof-of-work-based blockchain that relies on a numeric target for the validation of blocks. We also show that if miners regularly broadcast status reports of their partial proof-of- work, the hash rate estimates are signi cantly more accurate at a cost of slightly higher bandwidth. Whether using only the blockchain, or the additional information in status reports, merchants can use our techniques to quantify in real-time the threat of double-spend attacks.

References
[1] 2015. The Bitcoin Lightning Network: Scalable Off-Chain Instant Payments. https://lightning.network/lightning-network-paper.pdf. (July 2015).
[2] 2016. Gnosis. https://www.gnosis.pm. (November 2016).
[3] Asaph Azaria, Ariel Ekblaw, Thiago Vieira, and Andrew Lippman. 2016. "MedRec: Using Blockchain for Medical Data Access and Permission Management. In Proc. Intl. Conf. on Open and Big Data. 25–30.
[4] Adam Back, Matt Corallo, Luke Dashjr, Mark Friedenbach, Gregory Maxwell, Andrew Miller, Andrew Poelstra, Jorge Timón, and Pieter Wuille. 2014. Enabling Blockchain Innovations with Pegged Sidechains. Technical report. (Oct 22 2014).
[5] Simon Barber, Xavier Boyen, Elaine Shi, and Ersin Uzun. 2012. Bitter to better—how to make bitcoin a better currency. In International Conference on Financial Cryptography and Data Security. Springer, 399–414.
[6] Bryan Bishop. 2015. bitcoin-dev mailling list: Weak block thoughts... https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-Septembe011158.html. (Sep 2015).
[7] bitcoin 2015. Confirmation. https://en.bitcoin.it/wiki/Confirmation. (February 2015).
[8] Joseph Bonneau. 2015. How long does it take for a Bitcoin transaction to be confirmed? https://coincenter.org/2015/11/what-does-it-meanfor-a-bitcoin-transaction-to-be-confirmed/. (November 2015).
[9] J. Bonneau, A. Miller, J. Clark, A. Narayanan, J.A. Kroll, and E.W. Felten. 2015. SoK: Research Perspectives and Challenges for Bitcoin and Cryptocurrencies. In IEEE S&P. 104–121. http://doi.org/10.1109/ SP.2015.14
[10] George Casella and Roger L. Berger. 2002. Statistical inference. Brooks Cole, Pacific Grove, CA. http://opac.inria.frecord=b1134456
[11] Kyle Croman et al. 2016. On Scaling Decentralized Blockchains . In Workshop on Bitcoin and Blockchain Research.
[12] Digix. 2017. https://www.dgx.io/. (Last retrieved June 2017).
[13] DigixDAO. 2017. https://www.dgx.io/dgd/. (Last retrieved June 2017).
[14] J. Douceur. 2002. The Sybil Attack. In Proc. Intl Wkshp on Peer-to-Peer Systems (IPTPS).
[15] Bradley Efron. 1982. The jackknife, the bootstrap and other resampling plans. Society for industrial and applied mathematics (SIAM).
[16] Ethash. 2017. https://github.com/ethereum/wiki/wiki/Ethash. (Last retrieved June 2017).
[17] ethereum. Ethereum Homestead Documentation. http://ethdocs.org/en/latest/. (????).
[18] Etheria. 2017. http://etheria.world. (Last retrieved June 2017).
[19] Ittay Eyal and Emin Gün Sirer. 2014. Majority is not enough: Bitcoin mining is vulnerable. Financial Cryptography (2014), 436–454. http://doi.org/10.1007/978-3-662-45472-5_28
[20] William Feller. 1968. An Introduction to Probability Theory and its Applications: Volume I. Vol. 3. John Wiley & Sons London-New YorkSydney-Toronto.
[21] Juan Garay, Aggelos Kiayias, and Nikos Leonardos. 2015. The bitcoin backbone protocol: Analysis and applications. In Annual International Conference on the Theory and Applications of Cryptographic Techniques. Springer, 281–310.
[22] Arthur Gervais, Ghassan O. Karame, Karl Wust, Vasileios Glykantzis, Hubert Ritzdorf, and Srdjan Capkun. 2016. On the Security and Performance of Proof of Work Blockchains. https://eprint.iacr.org/2016/555. (2016).
[23] Hashcash. 2017. https://en.bitcoin.it/wiki/Hashcash. (Last retrieved June 2017).
[24] Ethan Heilman, Leen Alshenibr, Foteini Baldimtsi, Alessandra Scafuro, and Sharon Goldberg. 2017. TumbleBit: An untrusted Bitcoincompatible anonymous payment hub. In Proc. ISOC Network and Distributed System Security Symposium (NDSS).
[25] Svante Janson. 2014. Tail Bounds for Sums of Geometric and Exponential Variable. Technical Report. Uppsala University.
[26] Litecoin. 2017. https://litecoin.org. (Last retrieved June 2017).
[27] Satoshi Nakamoto. 2009. Bitcoin: A Peer-to-Peer Electronic Cash System. https://bitcoin.org/bitcoin.pdf. (May 2009).
[28] A. Pinar Ozisik, Gavin Andresen, George Bissias, Amir Houmansadr, and Brian Neil Levine. 2016. A Secure, Efficient, and Transparent Network Architecture for Bitcoin. Technical Report UM-CS-2016-006. University of Massachusetts, Amherst, MA. https://web.cs.umass.edu/publication/details.php?id=2417
[29] Meni Rosenfeld. 2012. Analysis of hashrate-based double-spending. https://bitcoil.co.il/Doublespend.pdf. (December 2012).
[30] Ayelet Sapirshtein, Yonatan Sompolinsky, and Aviv Zohar. 2015. Optimal Selfish Mining Strategies in Bitcoin. https://arxiv.org/pdf/1507.06183.pdf. (July 2015).
[31] Eli Ben Sasson, Alessandro Chiesa, Christina Garman, Matthew Green, Ian Miers, Eran Tromer, and Madars Virza. 2014. Zerocash: Decentralized Anonymous Payments from Bitcoin. In IEEE S&P. 459–474. http://dx.doi.org/10.1109/SP.2014.36
[32] Yonatan Sompolinsky and Aviv Zohar. 2015. Secure high-rate transaction processing in Bitcoin. Financial Cryptography and Data Security (2015). http://doi.org/10.1007/978-3-662-47854-7_32
[33] Yonatan Sompolinsky and Aviv Zohar. 2016. Bitcoin’s Security Model Revisited. https://arxiv.org/abs/1605.09193. (May 2016).
[34] F. Tschorsch and B. Scheuermann. 2016. Bitcoin and Beyond: A Technical Survey on Decentralized Digital Currencies. IEEE Communications Surveys Tutorials PP, 99 (2016), 1–1. https://doi.org/10.1109/COMST. 2016.2535718
[35] Marko Vukolić. 2015. The quest for scalable blockchain fabric: Proof-ofwork vs. BFT replication. In International Workshop on Open Problems in Network Security. Springer, 112–125.
submitted by dj-gutz to myrXiv [link] [comments]

HowTo: Bitcoin Mining Tutorial/German Before You Start Mining Bitcoins in 2015[Things to Know] [FREE] Bitcoin Miner Build Program 2015 BEGINNERS TUTORIAL: Bitcoin Mining Mining Bitcoins [TUTORIAL]

Bitcoin Snapshot: October 2, 2015 Bitcoin is a combination of several things: a currency, a payment system, and a collection of algorithms and software implementations. The goal of bitcoin is to enable payments with low transaction costs. Bitcoin can also sometimes provide anonymity. One bitcoin (BTC) is worth about $238. (A year ago: $394.) Bitcoin is Secure. Bitcoin miners help keep the Bitcoin network secure by approving transactions. Mining is an important and integral part of Bitcoin that ensures fairness while keeping the Bitcoin network stable, safe and secure. Links. We Use Coins - Learn all about crypto-currency. Bitcoin News - Where the Bitcoin community gets news. 3. Bitcoin Mining Hardware CPU mining. When Bitcoin first started out, there weren’t a lot of miners out there. In fact, Satoshi, the inventor of Bitcoin, and his friend Hal Finney were a couple of the only people mining Bitcoin back at the time with their own personal computers.. Using your CPU (central processing unit—your computer’s brain) was enough for mining Bitcoin back in 2009 Bitcoin - Mining - Tutorialspoint. Posted: (3 days ago) With Bitcoins, the process of creating the currency is called mining. Bitcoin miners use specialized software and hardware to verify bitcoin transactions and to solve complex math problems and are compensated by a certain number of bitcoins in exchange. Mining bitcoins doesn't *find* new bitcoins, they are awarded by the network for a valid string. (the process above) Best way to earn bitcoin is to find work paying in bitcoin, next is to buy it, then if you're really sadistic, try mining. But don't get new hardware, find it cheap on ebay, but do your homework on what's needed to get it running.

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HowTo: Bitcoin Mining Tutorial/German

Bitcoin and Litecoin Mining Tutorial - Guide for Beginners Only - Duration: 11:52. Scratchy Cards 22,639 views. 11:52. ASIC AntMiner U1 USB Bitcoin Miner Beginner Friendly Setup Guide For Windows ... Published on Jan 20, 2015 Basically mining off your GPU will get you no where, you have to invest in atleast a few asic miners getting at least 800 g/Hash for it to be somewhat profitable as of ... Published on Feb 17, 2015. ... [Tutorial] Echtes Bitcoin Mining Per Smartphone App - Duration: ... Bitcoin Mining EASY keine Stromkosten/Hardware [German Tutorial] ... mining gpu 2015, cloud mining, free bitcoin, 500 eur per month, майнинг для профи и для новичков! - Duration: 34:27. ENjOY SiLENCE 4,048 views Before You Start Mining Bitcoins in 2015[Things to Know] - Duration: 8:10. ... Galaxy Kitty 33,210 views. 8:10. How To Scrypt Mine Litecoin Tutorial - LiteCoin For Beginners - Part 1 - Duration ...

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