构建基于PoA的ethereum私链

1. 为什么要构建私链？
2. 构建基于PoA的ethereum私链
3. 扩展：extradata 字段介绍

1. 为什么要构建私链？

构建私链有多个理由，主要包括：

数据隐私与安全性
- 控制数据访问：私链允许组织对谁可以访问和参与区块链网络进行控制，从而保护敏感数据。
- 防止恶意行为：与公链相比，私链更容易限制恶意攻击，因为只有经过授权的参与者才能加入。
高性能与可扩展性
- 快速交易处理：由于参与者数量较少，私链通常可以处理更高的交易速度，减少交易确认时间。
- 定制化配置：可以根据特定需求优化网络参数（如区块生成时间、共识算法等）。
定制化特性
- 灵活性：可以根据组织的需求定制共识机制、合约功能和网络架构，适应特定的业务场景。
- 专有协议：可实现专门的协议或应用，与公链的标准化和限制不同。
合规性与监管
- 满足合规要求：私链能够帮助企业遵循行业法规和标准，比如金融行业的合规要求。
- 审计和监管：能够更容易地实施审计和监控机制，确保遵循法律和规定。
低成本与资源优化
- 资源节省：在私链中，通常只需要维护少量的节点，减少了硬件和网络带宽的需求。
- 控制网络费用：由于没有激励机制（如矿工奖励），运营成本通常较低。
业务合作与联盟链
- 跨组织协作：私链可用于多个组织之间的合作，尤其是在供应链管理和金融交易中。
- 联盟链：可以构建联盟链，让特定合作伙伴共同参与，确保数据的透明性和可追溯性。
测试与开发：开发人员可以在私链上进行测试，验证智能合约和应用程序的功能，而不必担心对公共网络的影响。

2. 构建基于PoA的ethereum私链

2.1 创建账户

创建两个账户，分别为account 1和account 2，用做初始的验证者地址。

# node
# account 1
$ geth --datadir ./node account new
INFO [09-27|09:40:38.644] Maximum peer count                       ETH=50 total=50
INFO [09-27|09:40:38.645] Smartcard socket not found, disabling    err="stat /run/pcscd/pcscd.comm: no such file or directory"
Your new account is locked with a password. Please give a password. Do not forget this password.
Password:
Repeat password:

Your new key was generated

Public address of the key:   0x51C4d2FeEBBAd01c2202d7CE772de1D953571201
Path of the secret key file: node/keystore/UTC--2024-09-27T01-40-44.544853516Z--51c4d2feebbad01c2202d7ce772de1d953571201

- You can share your public address with anyone. Others need it to interact with you.
- You must NEVER share the secret key with anyone! The key controls access to your funds!
- You must BACKUP your key file! Without the key, it's impossible to access account funds!
- You must REMEMBER your password! Without the password, it's impossible to decrypt the key!

# account 2
$ geth --datadir ./node account new
INFO [09-27|09:41:29.078] Maximum peer count                       ETH=50 total=50
INFO [09-27|09:41:29.079] Smartcard socket not found, disabling    err="stat /run/pcscd/pcscd.comm: no such file or directory"
Your new account is locked with a password. Please give a password. Do not forget this password.
Password:
Repeat password:

Your new key was generated

Public address of the key:   0x19Eac074dba9BBa2Eb97FFE7BBA80A9E9E83EcBe
Path of the secret key file: node/keystore/UTC--2024-09-27T01-41-34.412585202Z--19eac074dba9bba2eb97ffe7bba80a9e9e83ecbe

- You can share your public address with anyone. Others need it to interact with you.
- You must NEVER share the secret key with anyone! The key controls access to your funds!
- You must BACKUP your key file! Without the key, it's impossible to access account funds!
- You must REMEMBER your password! Without the password, it's impossible to decrypt the key!

2.2 创建创世区块

配置创世区块的配置文件genesis.json，内容如下：

{
    "config": {
        "chainId": 377777,
        "homesteadBlock": 0,
        "eip150Block": 0,
        "eip155Block": 0,
        "eip158Block": 0,
        "byzantiumBlock": 0,
        "constantinopleBlock": 0,
        "petersburgBlock": 0,
        "istanbulBlock": 0,
        "berlinBlock": 0,
        "clique": {
            "period": 5,
            "epoch": 30000
        }
    },
    "difficulty": "1",
    "gasLimit": "8000000",
    "extradata": "0x000000000000000000000000000000000000000000000000000000000000000051C4d2FeEBBAd01c2202d7CE772de1D95357120119Eac074dba9BBa2Eb97FFE7BBA80A9E9E83EcBe0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
    "alloc": {
        "51C4d2FeEBBAd01c2202d7CE772de1D953571201": {
            "balance": "100000000000000000000"
        },
        "19Eac074dba9BBa2Eb97FFE7BBA80A9E9E83EcBe": {
            "balance": "100000000000000000000"
        }
    }
}

初始验证者地址必须通过extradata字段指定。

$ geth --datadir ./node init ./genesis.json

2.3 启动节点

创世区块创建后，就可以启动私链节点了。

# networkid 是genesis.json中指定的chainId
$ geth --datadir ./node --networkid 377777 

2.4 进入 Geth 控制台测试

$ geth attach ./node/geth.ipc
Welcome to the Geth JavaScript console!

instance: Geth/v1.13.15-stable-c5ba367e/linux-amd64/go1.22.7
at block: 1 (Fri Sep 27 2024 10:01:07 GMT+0800 (CST))
 datadir: /root/vscode/ethereum/node
 modules: admin:1.0 clique:1.0 debug:1.0 engine:1.0 eth:1.0 miner:1.0 net:1.0 rpc:1.0 txpool:1.0 web3:1.0

To exit, press ctrl-d or type exit
# 获取最新区块高度
> eth.blockNumber
1
# 获取最新区块信息
> eth.getBlock('latest')
{
  difficulty: 2,
  extraData: "0xd883010d0f846765746888676f312e32312e39856c696e757800000000000000ebcda637df33928e4ce34051f777ccac21c643a8dcd1984b019984af41d99d5c41ff73559c837b0204c7764c71d8b5b49ecf63a555ee127e3d0cc86673d3214100",
  gasLimit: 8007811,
  gasUsed: 0,
  hash: "0xe4c14eb995dbcc9652a53fa8d47402dead30fa82af57b11399f9db23b06ab78b",
  logsBloom: "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  miner: "0x0000000000000000000000000000000000000000",
  mixHash: "0x0000000000000000000000000000000000000000000000000000000000000000",
  nonce: "0x0000000000000000",
  number: 1,
  parentHash: "0xb2ad7555b68d5c1e334d44033ef78c869fa4248a64a976a172318126a3db55a7",
  receiptsRoot: "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
  sha3Uncles: "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
  size: 606,
  stateRoot: "0xc5f02ccb91cfbde9f92912bb02aac9b2601e9a6e41ea9335343fa1991d277a5a",
  timestamp: 1727402467,
  totalDifficulty: 3,
  transactions: [],
  transactionsRoot: "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
  uncles: []
}
# 获取账户余额
> eth.getBalance("0x51C4d2FeEBBAd01c2202d7CE772de1D953571201")
100000000000000000000
> eth.getBalance("0x19Eac074dba9BBa2Eb97FFE7BBA80A9E9E83EcBe")
100000000000000000000
# 获取账户列表
> eth.accounts
["0x51c4d2feebbad01c2202d7ce772de1d953571201", "0x19eac074dba9bba2eb97ffe7bba80a9e9e83ecbe"]

curl 命令测试：

# 获取最新区块高度，result 为十六进制字符串
$ curl -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}' http://localhost:8545
{"jsonrpc":"2.0","id":1,"result":"0x1"}
# 获取账户余额
curl -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"eth_getBalance","params":["0x19Eac074dba9BBa2Eb97FFE7BBA80A9E9E83EcBe","latest"],"id":1}' http://localhost:8545
{"jsonrpc":"2.0","id":1,"result":"0x56bc75e2d63100000"}

3. 扩展：extradata 字段介绍

extradata 字段是以太坊区块头的一部分，主要用于 Proof of Authority (PoA) 共识机制（如 Clique）。它包含特定的信息，以便于节点之间的共识和验证。以下是对 extradata 字段的详细介绍：

3.1 功能

签名者信息：extradata 通常包含当前区块的签名者（或验证者）地址。这些地址是网络中被授权生成区块的节点。
额外元数据：在某些情况下，可以包括其他自定义信息，如版本号或链的特定参数。

3.2 格式

extradata 是一个字节数组，其结构通常如下：

32个零字节：用于预留空间。
签名者地址：包含网络中所有签名者的地址，每个地址占 20 字节（40 个十六进制字符）。
65个零字节：用于填充，确保 extradata 的总字节长度符合要求。

3.3 示例

假设你有三个签名者地址，extradata 的构建步骤如下：

32个零字节（在十六进制表示为）：

0000000000000000000000000000000000000000000000000000000000000000

签名者地址：

0xD22688d01E3345Cc2911C95447a3a1bcE32CB741
0x9A265B5Ef402813ae057e53f12D2B19d9aA5CEb4
0x843D259ab8C380FA576Cb013503CF961B63d12BB

65个零字节：

00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

拼接结果：

0x0000000000000000000000000000000000000000000000000000000000000000D22688d01E3345Cc2911C95447a3a1bcE32CB7419A265B5Ef402813ae057e53f12D2B19d9aA5CEb4843D259ab8C380FA576Cb013503CF961B63d12BB00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

4. 使用场景

共识机制：在 PoA 网络中，extradata 用于确定哪个节点在某一时刻被授权生成新区块。
数据完整性：由于 extradata 是区块头的一部分，确保了与块的其他信息一起传递，增强了数据的完整性和一致性。

5. 注意事项

字节长度：确保 extradata 的字节长度符合预期，错误的格式可能导致链启动失败。
动态更新：在网络运行过程中，可以使用相应的 API 更新签名者信息，确保网络的正常运作。

声明：本作品采用署名-非商业性使用-相同方式共享 4.0 国际 (CC BY-NC-SA 4.0)进行许可，使用时请注明出处。

Author: mengbin

blog: mengbin

Github: mengbin92

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