在这里验证一下https://tools.aifuwu.net/wechat-pay-tools/apiv3-key-validator

C# 版本的解密方法：

 private static string ALGORITHM = "AES/GCM/NoPadding";

 private static int TAG_LENGTH_BIT = 128;

 private static int NONCE_LENGTH_BYTE = 12;

 private static string AES_KEY = API_KEY; //youkeyhere

 public static string AesGcmDecrypt(string associatedData, string nonce, string ciphertext)

 {

     GcmBlockCipher gcmBlockCipher = new GcmBlockCipher(new AesEngine());

     AeadParameters aeadParameters = new AeadParameters(

         new KeyParameter(Encoding.UTF8.GetBytes(AES_KEY)),

         128,

         Encoding.UTF8.GetBytes(nonce),

         Encoding.UTF8.GetBytes(associatedData));

     gcmBlockCipher.Init(false, aeadParameters);

     byte[] data = Convert.FromBase64String(ciphertext);

     byte[] plaintext = new byte[gcmBlockCipher.GetOutputSize(data.Length)];

     int length = gcmBlockCipher.ProcessBytes(data, 0, data.Length, plaintext, 0);

     return Encoding.UTF8.GetString(plaintext);

 }