本地区块链服务在物联网中的应用实例

本地区块链服务在物联网中的应用实例：分布式传感器数据共享平台

一、系统架构设计

二、硬件准备清单

三、软件栈配置

# 区块链核心
sudo apt install docker-compose
git clone https://github.com/hyperledger/fabric-samples
cd fabric-samples/test-network

# 物联网设备端
pip install micropython-lib
git clone https://github.com/adafruit/Adafruit_CircuitPython_DHT

# 网关服务
npm install -g @hyperledger/caliper-cli
npm install ethers mqttjs

四、实施步骤

1. 搭建本地区块链网络（Hyperledger Fabric）

# 启动测试网络
./network.sh up createChannel -c iotchannel

# 部署链码
./network.sh deployCC -ccn iotchaincode -ccp ../chaincode/javascript/ -ccl javascript

2. 编写物联网智能合约 (iotchaincode.js)

const { Contract } = require('fabric-contract-api');

class IoTContract extends Contract {
    async InitLedger(ctx) {
        await ctx.stub.putState('deviceCount', Buffer.from('0'));
    }

    async RecordData(ctx, deviceId, temp, humidity) {
        const timestamp = new Date().toISOString();
        const data = { deviceId, temp, humidity, timestamp };
        
        // 关键：哈希校验防止篡改
        const hash = crypto.createHash('sha256').update(JSON.stringify(data)).digest('hex');
        await ctx.stub.putState(`DATA_${timestamp}`, Buffer.from(JSON.stringify({...data, hash})));
        
        // 超温告警逻辑
        if (parseFloat(temp) > 30.0) {
            await ctx.stub.setEvent('HIGH_TEMP', Buffer.from(JSON.stringify({
                deviceId,
                temp,
                location: await this.GetDeviceLocation(ctx, deviceId)
            })));
        }
    }

    async GetDeviceHistory(ctx, deviceId) {
        const query = { selector: { deviceId } };
        const iterator = await ctx.stub.getQueryResult(JSON.stringify(query));
        return await this._iteratorToArray(iterator);
    }
}

3. ESP32传感器数据采集代码

#include <DHT.h>
#include <LoRa.h>
#include <ArduinoJson.h>

#define DHTPIN 4
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  LoRa.begin(868E6); // EU LoRa频段
  dht.begin();
}

void loop() {
  float temp = dht.readTemperature();
  float humidity = dht.readHumidity();
  
  if (!isnan(temp) && !isnan(humidity)) {
    StaticJsonDocument<200> doc;
    doc["device"] = "sensor01";
    doc["temp"] = temp;
    doc["humidity"] = humidity;
    doc["timestamp"] = millis();
    
    String output;
    serializeJson(doc, output);
    
    LoRa.beginPacket();
    LoRa.print(output);
    LoRa.endPacket();
  }
  delay(10000); // 10秒间隔
}

4. 区块链网关服务（Node.js）

const { Gateway } = require('fabric-network');
const mqtt = require('mqtt');
const fs = require('fs');

// MQTT连接
const mqttClient = mqtt.connect('mqtt://localhost:1883');
mqttClient.subscribe('sensors/#');

// Hyperledger连接
const gateway = new Gateway();
await gateway.connect({
  wallet,
  identity: 'admin',
  discovery: { enabled: true, asLocalhost: true }
});
const network = await gateway.getNetwork('iotchannel');
const contract = network.getContract('iotchaincode');

// 处理传感器数据
mqttClient.on('message', async (topic, message) => {
  const data = JSON.parse(message.toString());
  
  try {
    // 提交到区块链
    await contract.submitTransaction(
      'RecordData', 
      data.device, 
      data.temp.toString(), 
      data.humidity.toString()
    );
    
    console.log(`✅ 数据上链: ${data.temp}℃`);
  } catch (error) {
    console.error(`❌ 上链失败: ${error}`);
  }
});

5. 数据查询API（Express.js）

const express = require('express');
const app = express();
const { Gateway } = require('fabric-network');

app.get('/history/:deviceId', async (req, res) => {
  const gateway = new Gateway();
  await gateway.connect(/* 连接配置 */);
  const contract = gateway.getContract('iotchaincode');
  
  const history = await contract.evaluateTransaction(
    'GetDeviceHistory', 
    req.params.deviceId
  );
  
  res.json(JSON.parse(history.toString()));
});

// 实时数据SSE流
app.get('/realtime', (req, res) => {
  res.setHeader('Content-Type', 'text/event-stream');
  const listener = (event) => {
    if (event.eventName === 'HIGH_TEMP') {
      res.write(`data: ${event.payload.toString()}\n\n`);
    }
  };
  contract.addContractListener(listener);
});

app.listen(3000);

五、系统工作流程

1. 数据采集：ESP32每10秒采集温湿度数据
2. 无线传输：通过LoRa发送到区块链网关
3. 数据上链：网关验证后写入Fabric区块链
4. 智能告警：温度>30℃时触发事件
5. 数据查询：通过API获取历史数据或实时SSE流

六、安全增强措施

1. 设备身份认证

   // 设备注册智能合约
   async RegisterDevice(ctx, deviceId, publicKey) {
     const exists = await this._deviceExists(ctx, deviceId);
     if (exists) throw new Error('设备已注册');
     await ctx.stub.putState(`DEVICE_${deviceId}`, Buffer.from(publicKey));
   }
   

2. 数据签名验证

   // ESP32端添加数字签名
   #include <Crypto.h>
   #include <SHA256.h>
   
   SHA256 sha;
   String signature = sha.hmacHash(privateKey, dataString);
   

3. 传输层加密

   # 启用LoRaWAN加密
   LoRa.enableCrypto();
   LoRa.setKey("mySecretKey123456");
   

七、监控仪表盘实现（React）

function Dashboard() {
  const [realtimeData, setRealtimeData] = useState([]);
  
  useEffect(() => {
    const eventSource = new EventSource('/realtime');
    eventSource.onmessage = (e) => {
      setRealtimeData(prev => [...prev, JSON.parse(e.data)]);
    };
    
    return () => eventSource.close();
  }, []);

  return (
    <div>
      <h3>实时监控 (温度>30℃告警)</h3>
      <ul>
        {realtimeData.map((alert, i) => (
          <li key={i}>
            {alert.deviceId} 温度过高: {alert.temp}℃
          </li>
        ))}
      </ul>
    </div>
  );
}

八、部署与测试

1. 启动网络：

   cd fabric-samples/test-network
   ./network.sh up
   

2. 模拟传感器：

   # 模拟数据脚本
   import paho.mqtt.publish as publish
   import random, time
   
   while True:
       temp = random.uniform(20.0, 35.0)
       msg = f'{{"device":"sensor01", "temp":{temp:.1f}, "humidity":50}}'
       publish.single("sensors/temp", msg, hostname="localhost")
       time.sleep(5)
   

3. 验证区块链数据：

   docker exec cli peer chaincode query -C iotchannel -n iotchaincode \
     -c '{"Args":["GetDeviceHistory","sensor01"]}'
   

九、应用场景扩展

1. 冷链药品监控：实时追踪温度变化并永久记录
2. 工业设备预测性维护：记录设备状态历史
3. 智能电表数据共享：防篡改的能源消耗记录
4. 农业环境监测：分布式农场数据采集

关键优势：

• 数据不可篡改：所有传感器数据永久记录在区块链上
• 去中心化验证：多个节点共同验证数据真实性
• 自动执行规则：通过智能合约实现实时告警
• 零第三方依赖：完全本地化部署，无云服务依赖

此方案可在树莓派集群上运行，适合工厂、实验室等需要高数据可信度的物联网场景，同时保障数据主权和隐私安全。