It would be nice to be told what programming language this page is using.
Bitcoin From Scratch – Part 1
71–77 of 77 posts
Re: Bitcoin From Scratch – Part 1
#72Mining part is confusing for me. Is POW is essentially to achieve difficulty level ? You do in this while loop until you have achieved this difficulty level ? Is this the primary factor that differentiates having various protocol in crypto ?
There are different ways to think about it, but I find this the most illustrative.
Mining is about authorship of the blockchain. The system is simple enough; people broadcast transactions, and they get collected and entered into a shared ledger. But the details are tricky. Order is one major issue; does A or B come first? A and B may be mutually exclusive, so whichever is first is critical. Because the network is imperfect, and network users may be malicious, it is very important that we come up with an extremely robust way of deciding how transactions are entered into the blockchain. Authorship - that is, mining a block - is everything.
The simple solution is to make it random. If it's random, then no individual miner can reliably control authorship, and thus cannot engage in attacks like double spends (unless they control a majority of the mining power, i.e. a 51% attack).
POW is a way to achieve randomness in a robust way. The only way to mine a block is to solve a problem that can only be solved via brute-force hashing. This is costly to do, so incentives are offered to get people to do it via coinbase rewards and transaction fees. This adds to the security model because miners now have strong economic ties to the POW algorithm and blockchain with capital and marginal costs.
Of course, there are other ways to achieve randomness, but can you think of one that will force a decentralized network to achieve robust consensus (i.e. to not fork)? Much of the 'magic' of Bitcoin comes when you realize the incentives under which miners operate. Once a valid block is broadcast on the network, miners have extremely powerful economic incentives to accept this block and begin mining on top of it.
Consider what happens if, instead, the miner continues to mine at the 'old' block height. They may come up with a valid block fairly soon (it's random, so they have no way of knowing), but each moment that passes, the other miner's valid block is being transmitted over the network. Any subsequently transmitted valid solution is at a disadvantage in becoming the consensus, and that grows as time passes. Basically, any time spent mining on the old block once a valid one has been seen is pure waste. Since the entire network operates from these same incentives, consensus grows very strongly as no one wants to mine on a minority chain.
_____
Difficulty is a different issue; this is just a way to keep block times fairly consistent, even as the network grows and more mining power comes online. Because it is calculated directly from the block chain, difficulty rules follow the same strong incentives that build consensus on the majority chain.
Re: Bitcoin From Scratch – Part 1
#73Earlier quoted context omitted.
const { mine, sign, verify, hash, validateProofOfWork, stripTxSignatures, generatePrivateKey, getPublicKey } = require("./util"); What does this do? And will this really run in a browser? I think brosers don't have require()?
Es6 destructuring- should run in most modern browsers although I’m a Es5 transpiler fan still!
Most modern browsers have require()? I thought they only have import?
Re: Bitcoin From Scratch – Part 1
#74Mining part is confusing for me. Is POW is essentially to achieve difficulty level ? You do in this while loop until you have achieved this difficulty level ? Is this the primary factor that differentiates having various protocol in crypto ?
There are different ways to think about it, but I find this the most illustrative. Mining is about authorship of the blockchain. The system is simple enough; people broadcast transactions, and they get collected and entered into a shared ledger. But the details are tricky. Order is one major issue; does A or B come first? A and B may be mutually exclusive, so whichever is first is critical. Because the network is imp…
Makes bit more sense now than I read originally. But I guess I have lot more questions now than before i came to read. Will have check more on this
Re: Bitcoin From Scratch – Part 1
#75Earlier quoted context omitted.
You can see what your functions do by opening the file called util.js in the same directory. And, yes you can run this in the browser by either polyfilling "require" or transpiling it
By that logic, everything runs in a browser. The principle of computational equivalence tells us that one turing complete language can do what any other can. So yes, everything can be polyfilled or transpiled. But that does not really meet my understanding of "Runs in the browser".
Computational equivalence doesn't include things like networking and resource access if you run in a sandboxed environment.
Re: Bitcoin From Scratch – Part 1
#76Earlier quoted context omitted.
Really it’s not because it’s a sequence of glyphs first and foremost. It can be mapped to a number though.
Nope, no mapping necessary. 36 octets, so a single 288 bit number in base 2. (Big-endian, unsigned, I guess) Then convert to any base you want. (I should have probably used 32 octets so that it fits neatly in 256 bits)
Isn’t that a mapping? Because the primary purpose of the string of glyphs is readable by humans. Such representation is mapped to the numerical representation for storage in the computer. It may also be mapped to lines of ink written on a piece of paper for transmission
Re: Bitcoin From Scratch – Part 1
#77Earlier quoted context omitted.
Nope, no mapping necessary. 36 octets, so a single 288 bit number in base 2. (Big-endian, unsigned, I guess) Then convert to any base you want. (I should have probably used 32 octets so that it fits neatly in 256 bits)
Isn’t that a mapping? Because the primary purpose of the string of glyphs is readable by humans. Such representation is mapped to the numerical representation for storage in the computer. It may also be mapped to lines of ink written on a piece of paper for transmission
Oh, in my example, it's just a coincidence that the number was readable by humans! Other numbers may come out as complete gibberish.
The "mapping" you may be referring to is happening outside and subject to how your brain /your browser interpret it. (How do you know that when I posted the comment, that I didn't supply the raw bits of the number?! ;-))
Anyway, it was just a joke for low level-programmers I guess. Have a good day ;-)