username 字段的格式为：
${productId}${deviceName};${sdkappid};${connid};${expiry}
注意：${} 表示变量，并非特定的拼接符号。

password 字段格式为： 
${token};hmac 签名方法
其中 hmac 签名方法字段填写第三步用到的摘要算法，可选的值有 hmacsha256 和 hmacsha1。

#!/usr/bin/python
# -*- coding: UTF-8 -*-
import base64
import hashlib
import hmac
import random
import string
import time
import sys
# 生成指定长度的随机字符串
def RandomConnid(length):
    return  ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(length))
# 生成接入物联网通信平台需要的各参数
def IotHmac(productID, devicename, devicePsk):
     # 1. 生成 connid 为一个随机字符串，方便后台定位问题
     connid   = RandomConnid(5)
     # 2. 生成过期时间，表示签名的过期时间,从纪元1970年1月1日 00:00:00 UTC 时间至今秒数的 UTF8 字符串
     expiry   = int(time.time()) + 60 * 60
     # 3. 生成 MQTT 的 clientid 部分, 格式为 ${productid}${devicename}
     clientid = "{}{}".format(productID, devicename)
     # 4. 生成 MQTT 的 username 部分, 格式为 ${clientid};${sdkappid};${connid};${expiry}
     username = "{};12010126;{};{}".format(clientid, connid, expiry)
     # 5. 对 username 进行签名，生成token
     secret_key = devicePsk.encode('utf-8')  # convert to bytes
     data_to_sign = username.encode('utf-8')  # convert to bytes
     secret_key = base64.b64decode(secret_key)  # this is still bytes
     token = hmac.new(secret_key, data_to_sign, digestmod=hashlib.sha256).hexdigest()
     # 6. 根据物联网通信平台规则生成 password 字段
     password = "{};{}".format(token, "hmacsha256")
     return {
        "clientid" : clientid,
        "username" : username,
        "password" : password
     }
if __name__ == '__main__':
    print(IotHmac(sys.argv[1], sys.argv[2], sys.argv[3]))


python3 IotHmac.py "YOUR_PRODUCTID" "YOUR_DEVICENAME" "YOUR_PSK" 

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.util.*;
public class IotHmac {
 public static void main(String[] args) throws Exception {
System.out.println(IotHmac("YOUR_PRODUCTID","YOUR_DEVICENAME","YOUR_PSK"));
}
public static Map<String, String> IotHmac(String productID, String devicename, String 
devicePsk) throws Exception {
                    final Base64.Decoder decoder = Base64.getDecoder();
            //1. 生成 connid 为一个随机字符串，方便后台定位问题
            String connid = HMACSHA256.getRandomString2(5);
            //2. 生成过期时间，表示签名的过期时间,从纪元1970年1月1日 00:00:00 UTC 时间至今秒数的 UTF8 字符串
            Long expiry = Calendar.getInstance().getTimeInMillis()/1000 +600;
            //3. 生成 MQTT 的 clientid 部分, 格式为 ${productid}${devicename}
            String clientid = productID+devicename;
            //4. 生成 MQTT 的 username 部分, 格式为 ${clientid};${sdkappid};${connid};${expiry}
            String username = clientid+";"+"12010126;"+connid+";"+expiry;
            //5.  对 username 进行签名，生成token、根据物联网通信平台规则生成 password 字段
            String password = HMACSHA256.getSignature(username.getBytes(), decoder.decode(devicePsk)) + ";hmacsha256";
            Map<String,String> map = new HashMap<>();
            map.put("clientid",clientid);
            map.put("username",username);
            map.put("password",password);
            return map;
        }
        public static class HMACSHA256 {
            private static final String HMAC_SHA256 = "HmacSHA256";
            /**
             * 生成签名数据
             *
             * @param data 待加密的数据
             * @param key  加密使用的key
             * @return 生成16进制编码的字符串
             */
            public static String getSignature(byte[] data, byte[] key)  {
                    try {
                            SecretKeySpec signingKey = new SecretKeySpec(key, HMAC_SHA256);
                            Mac mac = Mac.getInstance(HMAC_SHA256);
                            mac.init(signingKey);
                            byte[] rawHmac = mac.doFinal(data);
                            return bytesToHexString(rawHmac);
                    }catch (Exception e) {
                            e.printStackTrace();
                    }
                    return null;
            }
        /**
         * byte[]数组转换为16进制的字符串
         *
         * @param bytes 要转换的字节数组
         * @return 转换后的结果
         */
        private static String bytesToHexString(byte[] bytes) {
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < bytes.length; i++) {
                String hex = Integer.toHexString(0xFF & bytes[i]);
                if (hex.length() == 1) {
                    sb.append('0');
                }
                sb.append(hex);
            }
            return sb.toString();
        }
        public static String getRandomString2(int length) {
            Random random = new Random();
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < length; i++) {
                int number = random.nextInt(3);
                long result = 0;
                switch (number) {
                    case 0:
                        result = Math.round(Math.random() * 25 + 65);
                        sb.append(String.valueOf((char) result));
                        break;
                    case 1:
                        result = Math.round(Math.random() * 25 + 97);
                        sb.append(String.valueOf((char) result));
                        break;
                    case 2:
                        sb.append(String.valueOf(new Random().nextInt(10)));
                        break;
                }
            }
            return sb.toString();
        }
    }
}


// 下面为node引入方式，浏览器的话，使用对应的方式引入crypto-js库
const crypto = require('crypto-js')

// 产生随机数的函数
const randomString = (len) => {
　　len = len || 32;
　　var chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
　　var maxPos = chars.length;
　　var pwd = '';
　　for (let i = 0; i < len; i++) {
　　　　pwd += chars.charAt(Math.floor(Math.random() * maxPos));
　　}
　　return pwd;
}
// 需要产品id，设备名和设备密钥
const productId = 'YOUR_PRODUCTID';
const deviceName = 'YOUR_DEVICENAME';
const devicePsk = 'YOUR_PSK';

// 1. 生成 connid 为一个随机字符串，方便后台定位问题
const connid =  randomString(5);
// 2. 生成过期时间，表示签名的过期时间,从纪元1970年1月1日 00:00:00 UTC 时间至今秒数的 UTF8 字符串
const expiry = Math.round(new Date().getTime() / 1000) + 3600 * 24;
// 3. 生成 MQTT 的 clientid 部分, 格式为 ${productid}${devicename}
const clientId = productId + deviceName;
// 4. 生成 MQTT 的 username 部分, 格式为 ${clientid};${sdkappid};${connid};${expiry}
const userName = `${clientId};12010126;${connid};${expiry}`;
//5.  对 username 进行签名，生成token、根据物联网通信平台规则生成 password 字段
const rawKey = crypto.enc.Base64.parse(devicePsk);   	// 对设备密钥进行base64解码
const token =  crypto.HmacSHA256(userName, rawKey);
const password = token.toString(crypto.enc.Hex) + ";hmacsha256";
console.log(`userName:${userName}\\npassword:${password}`);


#include "limits.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include "HAL_Platform.h"
#include "utils_base64.h"
#include "utils_hmac.h"

/* Max size of base64 encoded PSK = 64, after decode: 64/4*3 = 48*/
#define DECODE_PSK_LENGTH 48

/* MAX valid time when connect to MQTT server. 0: always valid */
/* Use this only if the device has accurate UTC time. Otherwise, set to 0 */
#define MAX_ACCESS_EXPIRE_TIMEOUT (0)

/* Max size of conn Id  */
#define MAX_CONN_ID_LEN (6)

/* IoT C-SDK APPID */
#define QCLOUD_IOT_DEVICE_SDK_APPID     "21****06"
#define QCLOUD_IOT_DEVICE_SDK_APPID_LEN (sizeof(QCLOUD_IOT_DEVICE_SDK_APPID) - 1)

static void HexDump(char *pData, uint16_t len)
{
    int i;

    for (i = 0; i < len; i++) {
        HAL_Printf("0x%02.2x ", (unsigned char)pData[i]);
    }
    HAL_Printf("\\n");
}

static void get_next_conn_id(char *conn_id)
{
    int i;
    srand((unsigned)HAL_GetTimeMs());
    for (i = 0; i < MAX_CONN_ID_LEN - 1; i++) {
        int flag = rand() % 3;
        switch (flag) {
            case 0:
                conn_id[i] = (rand() % 26) + 'a';
                break;
            case 1:
                conn_id[i] = (rand() % 26) + 'A';
                break;
            case 2:
                conn_id[i] = (rand() % 10) + '0';
                break;
        }
    }

    conn_id[MAX_CONN_ID_LEN - 1] = '\\0';
}

int main(int argc, char **argv)
{
    char *product_id    = NULL;
    char *device_name   = NULL;
    char *device_secret = NULL;

    char *username     = NULL;
    int   username_len = 0;
    char  conn_id[MAX_CONN_ID_LEN];

    char password[51]      = {0};
    char username_sign[41] = {0};

    char   psk_base64decode[DECODE_PSK_LENGTH];
    size_t psk_base64decode_len = 0;

    long cur_timestamp = 0;

    if (argc != 4) {
        HAL_Printf("please ./qcloud-mqtt-sign product_id device_name device_secret\\r\\n");
        return -1;
    }

    product_id    = argv[1];
    device_name   = argv[2];
    device_secret = argv[3];

    /* first device_secret base64 decode */
    qcloud_iot_utils_base64decode((unsigned char *)psk_base64decode, DECODE_PSK_LENGTH, &psk_base64decode_len,
                                  (unsigned char *)device_secret, strlen(device_secret));
    HAL_Printf("device_secret base64 decode:");
    HexDump(psk_base64decode, psk_base64decode_len);

    /* second create mqtt username
     * [productdevicename;appid;randomconnid;timestamp] */
    cur_timestamp = HAL_Timer_current_sec() + MAX_ACCESS_EXPIRE_TIMEOUT / 1000;
    if (cur_timestamp <= 0 || MAX_ACCESS_EXPIRE_TIMEOUT <= 0) {
        cur_timestamp = LONG_MAX;
    }

    // 20 for timestampe length & delimiter
    username_len = strlen(product_id) + strlen(device_name) + QCLOUD_IOT_DEVICE_SDK_APPID_LEN + MAX_CONN_ID_LEN + 20;
    username     = (char *)HAL_Malloc(username_len);
    if (username == NULL) {
        HAL_Printf("malloc username failed!\\r\\n");
        return -1;
    }

    get_next_conn_id(conn_id);
    HAL_Snprintf(username, username_len, "%s%s;%s;%s;%ld", product_id, device_name, QCLOUD_IOT_DEVICE_SDK_APPID,
                 conn_id, cur_timestamp);

    /* third use psk_base64decode hamc_sha1 calc mqtt username sign crate mqtt
     * password */
    utils_hmac_sha1(username, strlen(username), username_sign, psk_base64decode, psk_base64decode_len);
    HAL_Printf("username sign: %s\\r\\n", username_sign);
    HAL_Snprintf(password, 51, "%s;hmacsha1", username_sign);

    HAL_Printf("Client ID: %s%s\\r\\n", product_id, device_name);
    HAL_Printf("username : %s\\r\\n", username);
    HAL_Printf("password : %s\\r\\n", password);

    HAL_Free(username);

    return 0;
}