Two generals problem bitcoin mineral

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There are many different blockchain consensus algorithms being promoted these days. Academics like to evaluate these algorithms to see if they solve the byzantine generals problem. In terms of blockchains, the challenge is to get the entire world to agree on a particular blockchain. One of the aspects of byzantine fault tolerance BFT is that an algorithm always reaches a conclusion and never ends up in an indeterminate state. In other words, at some point people need to know with certainty that everyone is in agreement and that a minority of bad actors cannot halt the process completely.

Bitcoin and other Proof of Work algorithms define the best chain as the one with the most difficult proof of work. A problem with proof of work, from byzantine perspective, is that it is always possible for the blockchain to be two generals problem bitcoin mineral, it just becomes increasingly unlikely and uneconomical. In order to consider Bitcoin and similar blockchains to have BFT you must assume that The cosmos white paper claims a working byzantine fault tolerance algorithm whereby a group of block producers can unanimously agree on the next block.

I was thoroughly impressed at the thoroughness of their approach and the robustness of their two generals problem bitcoin mineral. DPOS is an algorithm whereby stakeholders elect an odd number of block producers.

Each round the block producers are shuffled and assigned a time slot in which they should produce a block. With this process in place, the longest chain is considered the best chain. It is impossible for a minority of block producers to create a longer chain because they would be producing fewer two generals problem bitcoin mineral per minute than the majority blockchain. Eventually the minority fork would become longer and global consensus would necessarily change. Members of Cosmos community recently discovered a particular sequence of events that could cause the LIB algorithm to break down by causing the network to split on two different LIB.

This vulnerability in the LIB algorithm does not constitute a breakdown of DPOS because the LIB algorithm was an optional addition designed to identify the number of confirmations required before an exchange has sufficient guarantees that a block will not get orphaned. The LIB algorithm is similar to the 6 confirmation algorithm used by Bitcoin. A problem with Cosmos is an in implicit assumption that the set of generals is fixed. At least for a given block.

Blocks are produced, votes are cast, and new generals can be elected. From this we can conclude that Cosmos has a different deadlock condition. Every algorithm makes certain tradeoffs. To achieve this with the same number of generals as Steem 21they consume network bandwidth similar to a sustained 5 transactions per second. On the other hand, Steem rarely has any missed blocks and even more rarely has an orphaned block.

After two blocks 6 seconds the probability being orphaned falls further. Anyone relying on the last irreversible block algorithm 40 seconds is protected against almost every conceivable scenario with a worst-case purely theoretical being stuck in a pending state on a minority fork until manual intervention.

There is one additional level of confirmation that could be implemented in DPOS: What you should notice with these numbers is that extra time buys insurance for the last 0.

Due to the law of diminishing returns economic marginal utilitythe value of increased confidence from People lose more from two generals problem bitcoin mineral fees than they would if 1 out of every 1 million transactions were to be randomly reversed.

Meanwhile, the cost of gaining that last 0. Both algorithms have their place, but I am two generals problem bitcoin mineral happy with the design tradeoffs made for DPOS compared to the other algorithms available.

At a high level: This gets me thinking on how many things we could do if knew two generals problem bitcoin mineral to coordinate and agree without needing a president. We need a definition of participation rate. How a DPOS algorithm will work within a network of sidechains? I don't know if it's on the same page with the "fabric" technology described in the roadmap, but I'm curious.

If you have time, the post is here. It seems a lot of people have been complaining in steemit. Here's one example from just two generals problem bitcoin mineral in general. Everytime I enter my phone number I get two generals problem bitcoin mineral message: Please try a different phone number.

I two generals problem bitcoin mineral tell you that we are working to separate moderation flagging from curating voting. This issue will be improved in time. With respect to phone numbers, we had to block certain classes of phone number due to abuse.

If you can share the first 4 digits of the number I will have our team investigate if it is on the block list. Good, you understood what I meant about the downvote. I wasn't all that clear. But the fact that you're working on this is great to hear! You may want a "Contact The Help Desk" button, next to the "Continue" button on the phone signup page, to retain legit new user signups.

I've noticed a few real complaints about this. I am now curious about the phone number issue. It wouldn't allow it in the sign up process.

It starts with Anyway, I was able to use a different number, I figured it was just some glitch. Asking users to disclose personal mobile phone numbers while also at the same time denying access to those who don't have mobile phone subscriptions is in itself both abusive to end-user security and elitist. Not to mention the inequality that manifests when some states force mobile phone registration on their users and others do not.

This extreme hack comparable to using a machine gun to kill a chicken is motivated by a desire to easily control abusers, which implies that the whole system is inherently flawed-- flawed by the two generals problem bitcoin mineral that useful content is cannot be separated from drivel by the rating system as it was designed.

It's also somewhat shocking that steemit does not recognize the important role anonymity plays with speech freedom that's critical to having a nanny-free community.

This new direction makes steemit. Perhaps it was never intended as such, but it's a pity to see a good tool get downgraded to Facebook-quality blogging. Selecting users who are not street-wise and thus willing to connect two generals problem bitcoin mineral info to their account has the side-effect reducing the two generals problem bitcoin mineral of posts to that of the intelligence of that crowd.

Also, for security purposes hacked account recovery a means of communicating is necessary. It's good to have the advanced user options you mention, but they sound cumbersome and impractical. Hundreds of thousands of participants are being forced into a position of having th buy their freedom in order to make the spam-fight a little more convenient for a few two generals problem bitcoin mineral, no?

The current model effectively encourages users to trade their privacy for time or money. If blocking the spammers makes it that much harder for new users to get in it's hardly worth it. Not to mention the time and effort of getting the right form of anonymous money. This overkill is being imposed on hundreds of thousands of users for the convenience of a few admins. It's not worth it. The high price in time and money has made the system inadequate for anonymous blogging.

Users will pay the price in freedom instead. Got to love distributed consensus. You have several good point, arguments, and further understanding. You also brought to like huge details and importance of reading the red flags. I mean, I bought some when they were cheap, but that is about it.

I saw it as a possible failure but also a decent risk at a long term investment. Bitcoin and similar blockchains to have BFT you must assume that A very informative and powerful sharing for us on these platforms these days. Will you do more videos explaining these issues in the future? I've noticed I often find it a two generals problem bitcoin mineral easier to digest your ideas when expressed in the form of video interviews and the likes.

Basically, what you're saying is, "The blockchain has stopped, but gossip still works, so we can gossip the conditions for starting a new chain"? How does this have anything to do with the BCA? One of the best part is we have so much space to improve on top of what you have implemented.

The Problem with Byzantine Generals. Proof of Work does not Solve Byzantine Generals Bitcoin and other Proof of Work algorithms define the best chain as the one with the most difficult proof of work. Cosmos White Paper The cosmos white paper claims a working byzantine fault tolerance algorithm whereby a group of block producers can unanimously agree on the next block.

The Real Problem - Who are the Generals? Trade Offs Every algorithm makes certain tradeoffs. Conclusion Due to the law of diminishing returns economic marginal utilitythe value of increased confidence from Authors get paid when people like you upvote their post. Good point, must be two rounds. We calculated odds of attack at one in a trillion so won't change it. Nice read dantheman - thanks. Thought I was in for a history lesson, still learnt something though.

Thanks for the clarifications. Side chains are part of fabric. More to come on that.

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Now, this is a fair question. If you know anything about the blockchain architecture, you instinctively conclude that "no", it's quite improbable that anyone will break it. In practice, it's basically impossible.

It's quite amazing that most of my peer programmers have a very difficult time overcoming the prejudice against cryptocurrencies. I have no idea where this prejudice comes from, but I know very smart people that can solve the most difficult web scalability problems, but that never once glanced over Satoshi Nakamoto extremely short original paper describing the blockchain.

A Peer-to-Peer Electronic Cash System paper is so ridiculously small and easy to understand that most computer science students should be able to understand it. So all the smart programmers I know should be able to grasp it in a coffee break. Any average programmer should be able to read and understand this paper in 30 minutes or so. You can simplify a mental model of it as a Linked List, each node of the List is what we call a Block.

The catch is that each block has the hash signature of the previous block, thus creating a secure "chain". Yes, in computer science terms, we're dealing with undergraduate levels of data structures here.

If you understand a Linked List and a stupid Binary Tree, plus the easiest crypto thing to understand, a stupid Digest Hash such as SHA, and boom, you understand the basic backbone of the blockchain database. Yes, it is just a database. A distributed-database to be more exact. Or a very crude and simple distributed database for that matter. It is not very efficient, and it pales in comparison to more serious NoSQL distributed databases such as Redis or Cassandra. So the query-abilities are basically non-existent beyond finding a block by its identity.

Of course, the Bitcoin source-code is more sophisticated than that but the basics are really so ridiculous that you don't need more than 20 lines of Ruby code to replicate it.

Check out this example implementation from Gerald Bauer. Now, either you need to have a centralized "master-copy" out of which all other copies replicate from. Or you need some form of "consensus" between the different copies.

How do you reach consensus between rogue, random node spread across the globe? In a nutshell, imagine that you have Byzantine generals, each with their own armies, surrounding a hostile city.

Now, you can either attack or retreat. But all generals must either do one or the other, in consensus. How do you reach consensus when you don't have direct communication with all the generals and, worse, when some of the generals may be traitors or double-agents? That's the kind of problem we face here. Anyone on the internet can download a copy of the blockchain, and they can check that the blocks are valid and unadulterated by recomputing the digest hashes for each block. That's why Satoshi added the so-called "Proof of Work" to the equation.

Remember that I said that each block is chained together to the previous by containing the hash of the previous block? Computing a digest hash is quite trivial these days. Now, what if I ask you to find the hash that starts with a certain amount of "zeroes" in the beginning of the hash?

How do I know that I had to prepend ""? I don't, I have to start from 0 and incrementing one by one until I find the hash with the format I want. If we check from Gerald' example we would implement this lookup like this:. Just a simple SHA takes somewhere between 0. Now how long does it take to find that "" which we call a "nonce"?

Yep, considerably more, now it takes 0. We can increase the "difficult" variable to make it even more laborious to find the nonce. And that's exactly how Bitcoin is implemented: What a miner does is compute a loop, incrementing nonces, over the block digest to find the correct nonce.

Once a nonce is found, the miner can add the block to the blockchain and broadcast it to other nodes. The other nodes can then double-check and now it's just the 0. When the nodes double-check and confirm the nonce, they all add the block to the top of the blockchain.

And usually, when the other miners keep adding other blocks on top of that, that block becomes "solidified". The most recent block on the top of the blockchain is usually unstable, but once you have more blocks on top of it, it is said to be more "guaranteed".

Which is why most exchanges and other services that accept bitcoin wait for the so-called "6 blocks" confirmation. And because the difficulty is such that the fastest node takes around "10 minutes" to find that nonce, a block is said to be "secure" when around 1-hour passes and 6 blocks are added after it.

Mining is the act of signing and confirming blocks to the blockchain. It's a maintenance service, which is why you reward miners with "transaction fees" and a couple of "satoshis" fractions of 1 Bitcoin , for their work. And also why you call this "Proof of Work" because when someone finds a nonce, we know it had to go through a lot of hash computation to reach it.

You need to have an absurd capacity to be able to mine Bitcoins nowadays. No one will use a home-built rig to do it.

One must build special hardware, such as the famous AntMiners. Each crypto-currency different from Bitcoin calculates hashes differently so the hashrate differs from coin to coin. The current Hash Power of the entire Bitcoin consensus network is almost reaching 14 EH exa-hashes or millions of tera-hashes. So, let's say that I am a billionaire and I want to troll the Bitcoin community by adding enough hash power to surpass the entire hash power of the network.

And this is without adding the energy required to boot and run those machines, of course. But even then, do you know what happens? Remember that difficult variable I mentioned above? It will adjust again, to make sure the next block takes 10 minutes to compute again!

Then, no, even if you're willing to put USD 1. And that's how Bitcoin deals with Byzantine generals in this consensus network. But how do you add new blocks and make the other nodes accept your new block? In Ruby if you do: If we check from Gerald' example we would implement this lookup like this: Can we break this? Now, you will understand why we talk about "hash power" when we talk about mining. I want to find 4 zeros "" in the hash:

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