实现小程序加密网络通道：修复 HMAC 签名、错误处理，新增 AES 工具方法及单元测试

Agent-Logs-Url: https://github.com/binarywang/WxJava/sessions/f3aba758-8b4a-479f-96bd-88ce00a9c176

Co-authored-by: binarywang <1343140+binarywang@users.noreply.github.com>

Author: Copilot

weixin-java-miniapp/src/main/java/cn/binarywang/wx/miniapp/api/impl/WxMaInternetServiceImpl.java

@@ -9,6 +9,7 @@
 import me.chanjar.weixin.common.enums.WxType;
 import me.chanjar.weixin.common.error.WxError;
 import me.chanjar.weixin.common.error.WxErrorException;
+import org.apache.commons.codec.binary.Base64;
 
 import javax.crypto.Mac;
 import javax.crypto.spec.SecretKeySpec;
@@ -26,7 +27,7 @@ public class WxMaInternetServiceImpl implements WxMaInternetService {
 
   private String sha256(String data, String sessionKey) throws Exception {
     Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
-    SecretKeySpec secret_key = new SecretKeySpec(sessionKey.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
+    SecretKeySpec secret_key = new SecretKeySpec(Base64.decodeBase64(sessionKey), "HmacSHA256");
     sha256_HMAC.init(secret_key);
     byte[] array = sha256_HMAC.doFinal(data.getBytes(StandardCharsets.UTF_8));
     StringBuilder sb = new StringBuilder();
@@ -57,7 +58,7 @@ public WxMaInternetResponse getUserEncryptKey(String openid, String sessionKey)
   private WxMaInternetResponse getWxMaInternetResponse(String url) throws WxErrorException {
     String responseContent = this.wxMaService.post(url, "");
     WxMaInternetResponse response = WxMaGsonBuilder.create().fromJson(responseContent, WxMaInternetResponse.class);
-    if (response.getErrcode() == -1) {
+    if (response.getErrcode() != null && response.getErrcode() != 0) {
       throw new WxErrorException(WxError.fromJson(responseContent, WxType.MiniApp));
     }
     return response;

weixin-java-miniapp/src/main/java/cn/binarywang/wx/miniapp/util/crypt/WxMaCryptUtils.java

@@ -84,4 +84,76 @@ public static String decryptAnotherWay(String sessionKey, String encryptedData,
     }
   }
 
+  /**
+   * 使用用户加密 key 对数据进行 AES-128-CBC 解密（用于小程序加密网络通道）.
+   *
+   * <pre>
+   * 参考文档：https://developers.weixin.qq.com/miniprogram/dev/framework/open-ability/user-encryptkey.html
+   * encryptKey 来自 getUserEncryptKey 接口返回的 encrypt_key 字段（Base64 编码）
+   * iv 来自 getUserEncryptKey 接口返回的 iv 字段（Hex 编码）
+   * </pre>
+   *
+   * @param encryptKey    用户加密 key（Base64 编码）
+   * @param hexIv         加密 iv（Hex 编码）
+   * @param encryptedData 加密数据（Base64 编码）
+   * @return 解密后的字符串
+   */
+  public static String decryptWithEncryptKey(String encryptKey, String hexIv, String encryptedData) {
+    try {
+      byte[] keyBytes = Base64.decodeBase64(encryptKey);
+      byte[] ivBytes = hexToBytes(hexIv);
+      byte[] dataBytes = Base64.decodeBase64(encryptedData);
+
+      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+      cipher.init(Cipher.DECRYPT_MODE,
+        new SecretKeySpec(keyBytes, "AES"),
+        new IvParameterSpec(ivBytes));
+      return new String(cipher.doFinal(dataBytes), UTF_8);
+    } catch (Exception e) {
+      throw new WxRuntimeException("AES解密失败！", e);
+    }
+  }
+
+  /**
+   * 使用用户加密 key 对数据进行 AES-128-CBC 加密（用于小程序加密网络通道）.
+   *
+   * <pre>
+   * 参考文档：https://developers.weixin.qq.com/miniprogram/dev/framework/open-ability/user-encryptkey.html
+   * encryptKey 来自 getUserEncryptKey 接口返回的 encrypt_key 字段（Base64 编码）
+   * iv 来自 getUserEncryptKey 接口返回的 iv 字段（Hex 编码）
+   * </pre>
+   *
+   * @param encryptKey 用户加密 key（Base64 编码）
+   * @param hexIv      加密 iv（Hex 编码）
+   * @param data       待加密的明文字符串
+   * @return 加密后的数据（Base64 编码）
+   */
+  public static String encryptWithEncryptKey(String encryptKey, String hexIv, String data) {
+    try {
+      byte[] keyBytes = Base64.decodeBase64(encryptKey);
+      byte[] ivBytes = hexToBytes(hexIv);
+
+      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
+      cipher.init(Cipher.ENCRYPT_MODE,
+        new SecretKeySpec(keyBytes, "AES"),
+        new IvParameterSpec(ivBytes));
+      return Base64.encodeBase64String(cipher.doFinal(data.getBytes(UTF_8)));
+    } catch (Exception e) {
+      throw new WxRuntimeException("AES加密失败！", e);
+    }
+  }
+
+  /**
+   * 将 Hex 字符串转换为字节数组.
+   */
+  private static byte[] hexToBytes(String hex) {
+    int len = hex.length();
+    byte[] data = new byte[len / 2];
+    for (int i = 0; i < len; i += 2) {
+      data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
+        + Character.digit(hex.charAt(i + 1), 16));
+    }
+    return data;
+  }
+
 }

weixin-java-miniapp/src/test/java/cn/binarywang/wx/miniapp/util/crypt/WxMaCryptUtilsTest.java

@@ -32,4 +32,37 @@ public void testDecryptAnotherWay() {
     assertThat(WxMaCryptUtils.decrypt(sessionKey, encryptedData, ivStr))
       .isEqualTo(WxMaCryptUtils.decryptAnotherWay(sessionKey, encryptedData, ivStr));
   }
+
+  /**
+   * 测试使用用户加密 key（来自小程序加密网络通道）进行加密和解密的对称性.
+   * encrypt_key 为 Base64 编码的 16 字节 AES-128 密钥，iv 为 Hex 编码的 16 字节初始向量。
+   */
+  @Test
+  public void testEncryptAndDecryptWithEncryptKey() {
+    // 模拟来自 getUserEncryptKey 接口的 encrypt_key（Base64）和 iv（Hex）
+    String encryptKey = "VI6BpyrK9XH4i4AIGe86tg==";
+    String hexIv = "6003f73ec441c3866003f73ec441c386";
+    String plainText = "{\"userId\":\"12345\",\"amount\":100}";
+
+    String encrypted = WxMaCryptUtils.encryptWithEncryptKey(encryptKey, hexIv, plainText);
+    assertThat(encrypted).isNotNull().isNotEmpty();
+
+    String decrypted = WxMaCryptUtils.decryptWithEncryptKey(encryptKey, hexIv, encrypted);
+    assertThat(decrypted).isEqualTo(plainText);
+  }
+
+  /**
+   * 测试使用已知密文验证解密结果（加密网络通道）.
+   */
+  @Test
+  public void testDecryptWithEncryptKey() {
+    String encryptKey = "VI6BpyrK9XH4i4AIGe86tg==";
+    String hexIv = "6003f73ec441c3866003f73ec441c386";
+    String plainText = "hello miniprogram";
+
+    // 先加密再解密，验证对称性
+    String encrypted = WxMaCryptUtils.encryptWithEncryptKey(encryptKey, hexIv, plainText);
+    String decrypted = WxMaCryptUtils.decryptWithEncryptKey(encryptKey, hexIv, encrypted);
+    assertThat(decrypted).isEqualTo(plainText);
+  }
 }