Talking about blockchain (01): A macro comparison of Bitcoin, Ethereum, and Hyperledger technology

Today is the opening of the "Talking about Blockchain" column. I have been following Babbitt for some years, but today is my first day as a columnist. Let me introduce myself first. Tan Guopeng: Founder of Bitbill (bitbill.com), the earliest explorer of Bitcoin payment. He has been engaged in the research and exploration of Bitcoin, Ethereum, Hyperledger and other blockchains, and is currently the head of blockchain research and development at Sany Group. Talking about blockchain means talking about blockchain for Tan Guopeng. This column is planned to be written from issue 01 to issue 108, mainly focusing on technology sharing, and will also include blockchain business models, personal thoughts and other content.

Serious reminder: Any content and opinions in this column represent personal opinions only.

Now let's get to the point. Students who are familiar with Bitcoin technology often feel confused when learning Ethereum and Hyperledger (both refer to Hyperledger Fabric). Let's sort it out as follows:

1. Biggest confusion: What is worldstate?

There is no concept of accounts in Bitcoin, and all balances are calculated through UTXO . Ethereum and Hyperledger both have the concept of accounts. Ethereum accounts are divided into ordinary accounts and contract accounts. Each account has a corresponding permanent storage space to store the account's ether balance, bytecode, counter (used to prevent replay attack), and other key-value pairs. The account in Hyperledger is chaincodeID . Each deloped chaincode (chaincode is the name of the smart contract in Hyperledger) is an account. Each account also has a corresponding permanent storage space to store custom key-value pairs. The permanent storage space in Ethereum and Hyperledger is worldstate.

2. Where is the worldstate stored?

This question will make Bitcoin developers more confused, because for Bitcoin, each node maintains a complete blockchain, and no other data needs to be stored. Where is the worldstate information (that is, account-related information) stored for Ethereum and hyperledger? Is it in the blockchain or somewhere else? Is it stored on the chain or off the chain? The answer is off the chain. In fact, each block of Ethereum and hyperledger will only contain a hash of the entire data set of the current corresponding worldstate, called worldstate-hash. The complete worldstate data of Ethereum is stored in ~/.ethereum , and the worldstate data of hyperledger is stored in /var/hyperledger/production/db .

3. Different block speeds

Everyone should be clear about this. Bitcoin generates a block every 10 minutes on average (for beginners, let me explain that it is an average, not a fixed time. The processing logic is that as long as the miner calculates the answer, the block will be generated immediately, which may be as fast as a few seconds or as slow as a few hours). Ethereum generates a block every 10 seconds on average, and Hyperledger generates a block for each transaction by default. It also supports CommitTxBatch mode, where multiple transactions generate a block (this is just my understanding and has not been fully verified). That is to say, Hyperledger will not generate a block when there is no transaction. For example, if there is no transaction for a day, no new block will be generated for a day. Bitcoin is different from Ethereum. Blocks will be generated even if there is no transaction (because miners will publish coinbase transactions themselves to earn mining fees).

4. Different consensus mechanisms

Bitcoin is the originator of PoW, Ethereum currently also uses PoW, and Hyperledger uses the IBM version of PBFT. PoW requires the design of tokens (Bitcoin and Ethereum, used to reward miners and prevent attacks), but PBFT does not necessarily need to do so, so Hyperledger currently does not have a built-in token.

5. Do Ethereum and Hyperledger support SPV?

SPV has played an indispensable role in the success of Bitcoin. Satoshi Nakamoto's genius is reflected in many aspects, and SPV is one of them. If there is no SPV, I believe that few people will play Bitcoin now. Imagine downloading a wallet and waiting for several days to synchronize before using it. What kind of experience is that! I haven't studied whether Ethereum currently supports SPV. But hyperledger currently does not support it (currently talking about fabric version 0.6.1), and not supporting SPV will be a disaster!

This is the first post today, so I’ll write this much for now. I’ll continue another day!