Blockchain: A technical primer

154 点作者 halfbrown将近 7 年前

9 条评论

apo将近 7 年前

A blockchain is a digital and distributed ledger of transactions, recorded and replicated in real time across a network of computers or nodes (figure 1). Every transaction must be cryptographically validated via a consensus mechanism executed by the nodes before being permanently added as a new “block” at the end of the “chain.” There is no need for a central authority to approve the transaction, which is why blockchain is sometimes referred to as a peer-to-peer trustless mechanism.I see this kind of explanation a lot. It's misleading at best. A block chain is most definitely not a ledger, as is claimed by too many sources to count.A block chain is a tool allowing a group of users to produce a single, unique transaction log.To this end, transactions are grouped into blocks. A block references two pieces of information: (1) its ordered list of transactions; and (2) its parent block. Two or more blocks may claim the same block as a parent. Therefore, a collection of blocks can be assembled into a tree with one or more children pointing to a parent.Each user maintains its own copy of the tree. All paths through the tree are followed and scored. The path with the highest score is designated as the active chain.The active chain is what many people think of when they use the term "Blockchain."However, the structure of this chain is mostly boring and unremarkable. The most interesting thing about it are transactions. Like blocks, transactions link together. Additionally, transactions run programs that induce global state changes.The secret sauce of "Blockchain" boils down to incentivizing each user to choose the same active chain in an adversarial environment. The best-tested procedure uses "proof-of-work."If the relative order of events plays an important part in what you're trying to do, and you operate in an adversarial environment, then a block chain might help.Otherwise, there's not much a block chain can do for you.

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seibelj将近 7 年前

Blockchain is very applicable to industries where middlemen extract large value by being intermediaries between competing parties.As an example, in telecom there is the issue of settlement. Every phone call generates a Call Data Record (CDR) that has information about who called who, call length, etc. This is critical because every telco negotiates individual rates for voice, SMS, data roaming, etc. between every other carrier on earth (although often you negotiate with one company that provides a package rate for multiple telcos). Your "unlimited" plan obfuscates the fact that how you use your plan, what carriers the people you call are on, where you use data, reflect different levels of profitability for you as a customer.Large companies like Amdocs[0] make billions of dollars handling settlement for telcos. Every month, a carrier has to "settle" all of their CDR's with every other carrier. Issues get sorted out because CDR's never match perfectly, and then carriers pay each other to balance out based on their contractual obligations.A blockchain solution that all telcos agreed on would guarantee data correctness (CDR's all look alike), allow instant settlement and payment (settlement happens once a month), and eliminate the middlemen like Amdocs, Synchronoss, etc. in regards to settlement.Obviously this is a tough problem to crack, and you'd need to get the telcos on board, but I am explaining this as an example where blockchain could provide real value.Indeed, Maersk, the largest shipping conglomerate, is going to release a blockchain solution to move the international shipping industry away from paper and to a unified system.[1] Maersk is in a unique position to do this because they are the largest player, and most other companies just follow what they do, but I mention this as an example where blockchain can help competing companies interact more efficiently.[0] <a href="https://www.amdocs.com/" rel="nofollow">https://www.amdocs.com/</a>[1] <a href="https://www.economist.com/briefing/2018/04/26/the-global-logistics-business-is-going-to-be-transformed-by-digitisation" rel="nofollow">https://www.economist.com/briefing/2018/04/26/the-global-log...</a>

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gfs将近 7 年前

> In fact, it can be considered one of the biggest technology breakthroughs in recent history, similar to the advent of the Internet in the early 1990s.If this were the case, wouldn't we see the technology in the wild more? That seems like a bold claim for something that is still being vetted and explored.I certainly see value in blockchain but the applications that are using it today don't excite me. The hype puts me off but I am hoping to see it bloom into other areas of software that aren't ICOs or proof of concepts.

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rafiki6将近 7 年前

I find this to be less of a whitepaper and more of an opinion piece. For e.g."For example, two business parties transacting would not need to maintain their own record of the transaction and would use the blockchain as a single source of truth instead."Ummmmmm...isn't the whole idea of blockchain that we all have a copy (our version of the truth) and a transaction is validated by several participants or miners? That's basically how we get rid of the middlemen? The sentence is clearly trying to convey that this is somehow more efficient than a current system based on a centralized authority, but there's no actual evidence that this is true.Blockchain might bring efficiency to an industry like shipping that currently uses a VERY inefficient system, but it's disingenuous to tell others (especially if you are trying to sell something), that it is more efficient than a well implemented centralized system.

guiomie将近 7 年前

They explain the basics of permisionless blockchains and they go on and say "Prominent blockchain consortia include Enterprise Ethereum Alliance, R3, and Hyperledger", this can confuse people since R3 and Hyperledger are quite different from a permissionless chain with mining, and the value added of such platforms without crypto-currencies is highly debatable in my opinion.

mar77i将近 7 年前

> In fact, it can be considered one of the biggest technology breakthroughs in recent history, similar to the advent of the Internet in the early 1990s.Audibly sighing. read this: <a href="https://shkspr.mobi/blog/2018/06/how-i-became-leonardo-da-vinci-on-the-blockchain/" rel="nofollow">https://shkspr.mobi/blog/2018/06/how-i-became-leonardo-da-vi...</a>It's the internet of shit in crypto, all over again. Come on. There's nothing like 50% of the swarm simply declaring your transactions null and void, but that's obviously how the blockchain is currently operating for some ... uh, criminal reason.

volaski将近 7 年前

"technical primer", yeah right.I guess this counts as "technical" to people at Deloitte.

rdiddly将近 7 年前

Pretty good primer for newcomers, though it seems to take it as a given that blockchains are (or to hear them say it, "blockchain is") just fully as amazing and applicable as the hype suggests, and here's what you are going to have to do when you inevitably get with the program!

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xmly将近 7 年前

Another amateur's writing about blockchain. If you want the immutability, the blockchain is not immutable, just difficult to modify. Also you only need hash signature for this purpose.