Cette rubrique explique comment connecter un appareil à IoT Platform à l'aide du protocole CoAP (Constrained Application Protocol). L'exemple fourni utilise du code Java.
Contexte
CoAP convient aux appareils à faible consommation et aux ressources limitées, tels que les appareils NB-IoT. Pour plus d'informations sur la connexion d'un appareil à IoT Platform via CoAP, consultez la rubrique Connecter des appareils à IoT Platform via CoAP.
Remarque
Chine (Shanghai), Chine (Pékin), Chine (Shenzhen)
La connexion d'appareils à IoT Platform via CoAP n'est disponible que dans la région Chine (Shanghai).
Pour connecter un appareil à IoT Platform via CoAP, vous devez spécifier les paramètres requis, générer une signature pour l'appareil et effectuer d'autres opérations. Le processus de configuration est illustré à l'aide d'un exemple de code basé sur Eclipse Californium. Pour garantir la sécurité des données, le chiffrement symétrique est utilisé.
Préparer l'environnement de développement
Assurez-vous que l'environnement de développement Java suivant est prêt à l'emploi.
Système d'exploitation : Windows 10
Version JDK : JDK 8
Environnement de développement intégré (IDE) : IntelliJ IDEA Community Edition
Procédure
Ouvrez IntelliJ IDEA et créez un projet Maven. Exemple : IotCoap-demo.
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Ajoutez les dépendances suivantes au fichier pom.xml du projet, puis cliquez sur Load Maven Changes pour télécharger le package de dépendances. Cette opération permet d'importer le framework Californium, la boîte à outils Apache Commons et le package fastjson d'Alibaba Cloud.
<dependency> <groupId>org.eclipse.californium</groupId> <artifactId>californium-core</artifactId> <version>2.0.0-M17</version> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-lang3</artifactId> <version>3.5</version> </dependency> <dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.13</version> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.83</version> </dependency> -
Dans le répertoire /src/main/java du projet IotCoap-demo, créez une classe Java telle que IotCoapClientWithAes.java et saisissez le code. Exemple de code :
import java.io.IOException; import java.nio.charset.StandardCharsets; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.Set; import java.util.SortedMap; import java.util.TreeMap; import javax.crypto.Cipher; import javax.crypto.Mac; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.DecoderException; import org.apache.commons.codec.binary.Hex; import org.apache.commons.lang3.RandomUtils; import org.eclipse.californium.core.CoapClient; import org.eclipse.californium.core.CoapResponse; import org.eclipse.californium.core.Utils; import org.eclipse.californium.core.coap.CoAP; import org.eclipse.californium.core.coap.CoAP.Code; import org.eclipse.californium.core.coap.CoAP.Type; import org.eclipse.californium.core.coap.MediaTypeRegistry; import org.eclipse.californium.core.coap.Option; import org.eclipse.californium.core.coap.OptionNumberRegistry; import org.eclipse.californium.core.coap.OptionSet; import org.eclipse.californium.core.coap.Request; import org.eclipse.californium.elements.exception.ConnectorException; import com.alibaba.fastjson.JSONObject; /** * The following Eclipse Californium-based code shows how to connect a device to IoT Platform by using CoAP. * For more information about the development process and parameters of autonomous access, see the "Connect devices by using symmetric encryption" section in the Connect devices to IoT Platform over CoAP topic. */ public class IotCoapClientWithAes { // ======================== You must specify the following parameters. =========================== // The region ID. China (Shanghai) is used in this example. private static String regionId = "cn-shanghai"; // The ProductKey of the product to which your device belongs. private static String productKey = "ProductKey of your device"; // The DeviceName of the device. private static String deviceName = "DeviceName of your device"; // The DeviceSecret of the device. private static String deviceSecret = "DeviceSecret of your device"; //======================= End =========================== // Set the HMAC_ALGORITHM parameter to hmacsha1 or hmacmd5. The value that you specify must be the same as that of the signmethod parameter. private static final String HMAC_ALGORITHM = "hmacsha1"; // The endpoint that is used to connect a device to an IoT Platform instance over CoAP. If you use symmetric encryption, the port number of the endpoint is 5682. private static String serverURI = "coap://" + productKey + ".coap." + regionId + ".link.aliyuncs.com:5682"; // The topic to which messages are sent. In the IoT Platform console, you can create a custom topic and grant devices the Publish permission on the topic. private static String updateTopic = "/" + productKey + "/" + deviceName + "/user/update"; // token option private static final int COAP2_OPTION_TOKEN = 2088; // seq option private static final int COAP2_OPTION_SEQ = 2089; // The SHA-256 encryption algorithm. private static final String SHA_256 = "SHA-256"; private static final int DIGITAL_16 = 16; private static final int DIGITAL_48 = 48; // The CoAP client. private CoapClient coapClient = new CoapClient(); // The validity period of a token is seven days. After a token expires, you must obtain a new token. private String token = null; private String random = null; @SuppressWarnings("unused") private long seqOffset = 0; /** * Initialize the CoAP client. * * @param productKey: the ProductKey of the product to which your device belongs. * @param deviceName: the DeviceName of your device. * @param deviceSecret: the DeviceSecret of your device. */ public void connect(String productKey, String deviceName, String deviceSecret) { try { // The endpoint that is used for authentication. String uri = serverURI + "/auth"; // Only the POST method is supported. Request request = new Request(Code.POST, Type.CON); // Specify options. OptionSet optionSet = new OptionSet(); optionSet.addOption(new Option(OptionNumberRegistry.CONTENT_FORMAT, MediaTypeRegistry.APPLICATION_JSON)); optionSet.addOption(new Option(OptionNumberRegistry.ACCEPT, MediaTypeRegistry.APPLICATION_JSON)); request.setOptions(optionSet); // Specify the endpoint that you can use to authenticate the device. request.setURI(uri); // Specify the required parameters for an authentication request. request.setPayload(authBody(productKey, deviceName, deviceSecret)); // Send the authentication request. CoapResponse response = coapClient.advanced(request); System.out.println(Utils.prettyPrint(response)); System.out.println(); // Parse the response. JSONObject json = JSONObject.parseObject(response.getResponseText()); token = json.getString("token"); random = json.getString("random"); seqOffset = json.getLongValue("seqOffset"); } catch (ConnectorException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } /** * Send a message. * @param topic The topic to which messages are sent. * @param payload The content of the message. */ public void publish(String topic, byte[] payload) { try { // The endpoint of the topic. The syntax of a topic is /topic/${topic}. String uri = serverURI + "/topic" + topic; // Encrypt the seq option by using the AES encryption algorithm. seq=RandomUtils.nextInt(). String shaKey = encod(deviceSecret + "," + random); byte[] keys = Hex.decodeHex(shaKey.substring(DIGITAL_16, DIGITAL_48)); byte[] seqBytes = encrypt(String.valueOf(RandomUtils.nextInt()).getBytes(StandardCharsets.UTF_8), keys); // Only the POST method is supported. Request request = new Request(CoAP.Code.POST, CoAP.Type.CON); // Specify options. OptionSet optionSet = new OptionSet(); optionSet.addOption(new Option(OptionNumberRegistry.CONTENT_FORMAT, MediaTypeRegistry.APPLICATION_JSON)); optionSet.addOption(new Option(OptionNumberRegistry.ACCEPT, MediaTypeRegistry.APPLICATION_JSON)); optionSet.addOption(new Option(COAP2_OPTION_TOKEN, token)); optionSet.addOption(new Option(COAP2_OPTION_SEQ, seqBytes)); request.setOptions(optionSet); // Specify the endpoint of the topic. request.setURI(uri); // Specify the payload parameter. request.setPayload(encrypt(payload, keys)); // Send a message. CoapResponse response = coapClient.advanced(request); System.out.println(Utils.prettyPrint(response)); // Parse the result. String result = null; if (response.getPayload() != null) { result = new String(decrypt(response.getPayload(), keys)); } System.out.println("payload: " + result); System.out.println(); } catch (ConnectorException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (DecoderException e) { e.printStackTrace(); } } /** * Generate the parameters required for authentication. * * @param productKey: the ProductKey of the product to which your device belongs. * @param deviceName: the DeviceName of the device. * @param deviceSecret: the DeviceSecret of the device. * @return: the authentication request. */ private String authBody(String productKey, String deviceName, String deviceSecret) { // Create an authentication request. JSONObject body = new JSONObject(); body.put("productKey", productKey); body.put("deviceName", deviceName); body.put("clientId", productKey + "." + deviceName); body.put("timestamp", String.valueOf(System.currentTimeMillis())); body.put("signmethod", HMAC_ALGORITHM); body.put("seq", DIGITAL_16); body.put("sign", sign(body, deviceSecret)); System.out.println("----- auth body -----"); System.out.println(body.toJSONString()); return body.toJSONString(); } /** * Generate a signature for a device. * * @param params: the parameters that are required to generate a signature. * @param deviceSecret: the DeviceSecret of the device. * @return: a hexadecimal signature string. */ private String sign(JSONObject params, String deviceSecret) { // Sort the request parameters in alphabetical order. Set<String> keys = getSortedKeys(params); // Remove the sign, signmethod, version, and resources parameters. keys.remove("sign"); keys.remove("signmethod"); keys.remove("version"); keys.remove("resources"); // Obtain the plaintext of the signature. StringBuffer content = new StringBuffer(); for (String key : keys) { content.append(key); content.append(params.getString(key)); } // Generate a signature. String sign = encrypt(content.toString(), deviceSecret); System.out.println("sign content=" + content); System.out.println("sign result=" + sign); return sign; } /** * Sort the keys of a JSON object in alphabetical order. * * @param json: the JSON object whose keys you want to sort. * @return: the set of keys sorted in alphabetical order. */ private Set<String> getSortedKeys(JSONObject json) { SortedMap<String, String> map = new TreeMap<String, String>(); for (String key : json.keySet()) { String value = json.getString(key); map.put(key, value); } return map.keySet(); } /** * Specify an encryption algorithm by using the HMAC_ALGORITHM parameter. * * @param content: plaintext * @param secret: encryption key * @return: ciphertext */ private String encrypt(String content, String secret) { try { byte[] text = content.getBytes(StandardCharsets.UTF_8); byte[] key = secret.getBytes(StandardCharsets.UTF_8); SecretKeySpec secretKey = new SecretKeySpec(key, HMAC_ALGORITHM); Mac mac = Mac.getInstance(secretKey.getAlgorithm()); mac.init(secretKey); return Hex.encodeHexString(mac.doFinal(text)); } catch (Exception e) { e.printStackTrace(); return null; } } /** * SHA-256 * * @param str: the message that you want to encrypt. */ private String encod(String str) { MessageDigest messageDigest; String encdeStr = ""; try { messageDigest = MessageDigest.getInstance(SHA_256); byte[] hash = messageDigest.digest(str.getBytes(StandardCharsets.UTF_8)); encdeStr = Hex.encodeHexString(hash); } catch (NoSuchAlgorithmException e) { System.out.println(String.format("Exception@encod: str=%s;", str)); e.printStackTrace(); return null; } return encdeStr; } // Encrypt and decrypt data by using the AES algorithm. private static final String IV = "543yhjy97ae7fyfg"; private static final String TRANSFORM = "AES/CBC/PKCS5Padding"; private static final String ALGORITHM = "AES"; /** * key length = 16 bits */ private byte[] encrypt(byte[] content, byte[] key) { return encrypt(content, key, IV); } /** * key length = 16 bits */ private byte[] decrypt(byte[] content, byte[] key) { return decrypt(content, key, IV); } /** * aes 128 cbc key length = 16 bits */ private byte[] encrypt(byte[] content, byte[] key, String ivContent) { try { SecretKeySpec keySpec = new SecretKeySpec(key, ALGORITHM); Cipher cipher = Cipher.getInstance(TRANSFORM); IvParameterSpec iv = new IvParameterSpec(ivContent.getBytes(StandardCharsets.UTF_8)); cipher.init(Cipher.ENCRYPT_MODE, keySpec, iv); return cipher.doFinal(content); } catch (Exception ex) { System.out.println( String.format("AES encrypt error, %s, %s, %s", content, Hex.encodeHex(key), ex.getMessage())); return null; } } /** * aes 128 cbc key length = 16 bits */ private byte[] decrypt(byte[] content, byte[] key, String ivContent) { try { SecretKeySpec keySpec = new SecretKeySpec(key, ALGORITHM); Cipher cipher = Cipher.getInstance(TRANSFORM); IvParameterSpec iv = new IvParameterSpec(ivContent.getBytes(StandardCharsets.UTF_8)); cipher.init(Cipher.DECRYPT_MODE, keySpec, iv); return cipher.doFinal(content); } catch (Exception ex) { System.out.println(String.format("AES decrypt error, %s, %s, %s", Hex.encodeHex(content), Hex.encodeHex(key), ex.getMessage())); return null; } } public static void main(String[] args) throws InterruptedException { IotCoapClientWithAes client = new IotCoapClientWithAes(); client.connect(productKey, deviceName, deviceSecret); client.publish(updateTopic, "hello coap".getBytes(StandardCharsets.UTF_8)); client.publish(updateTopic, new byte[] { 0x01, 0x02, 0x03, 0x05 }); } } -
Spécifiez les paramètres suivants.
Paramètre Description regionId ID de la région où se trouve IoT Platform. Vous pouvez afficher la région dans le coin supérieur gauche de la console IoT Platform.
Pour plus d'informations sur les ID de région, consultez la page Liste des régions.
productKey Informations sur le certificat de l'appareil que vous pouvez obtenir après avoir ajouté l'appareil dans la console IoT Platform. Vous pouvez afficher ces informations sur la page Device Details de la console IoT Platform.
deviceName deviceSecret serverURI Endpoint utilisé pour connecter l'appareil à IoT Platform via CoAP. Pour plus d'informations, consultez la rubrique Gérer les endpoints des instances. -
Exécutez le programme IotCoapClientWithAes.java.
L'exemple de code suivant montre le résultat de l'exécution. L'appareil peut communiquer avec IoT Platform après authentification.
sign content=clientIda1****RK0.devicedeviceNamedeviceproductKeya1OX****K0seq16timestamp1658909565141 sign result=7f3b76dc21e7******fec424838d1858 ----- auth body ----- {"clientId":"a1OXp8sXRK0.device","signmethod":"hmacsha1","sign":"7f3b76dc21e7******fec424838d1858","productKey":"a1OX****K0","deviceName":"device","seq":16,"timestamp":"1658909565141"} ==[ CoAP Response ]============================================ MID : 37682 Token : 6E1F******6B91 Type : ACK Status : 2.05 - CONTENT Options: {} RTT : 116 ms Payload: 85 Bytes --------------------------------------------------------------- {"random":"a25******6d44","seqOffset":1,"token":"mnx4OF0b******R000000.5ac7"} =============================================================== ==[ CoAP Response ]============================================ MID : 37683 Token : AC60******106E7 Type : ACK Status : 2.05 - CONTENT Options: {"Unknown (2090)":0x158a******6aa00} RTT : 118 ms Payload: 0 Bytes =============================================================== payload: null ==[ CoAP Response ]============================================ MID : 37684 Token : AA9******EFCC Type : ACK Status : 2.05 - CONTENT Options: {"Unknown (2090)":0x158a******f600} RTT : 103 ms Payload: 0 Bytes =============================================================== payload: null