/// <summary>
/// 将微信号回复用户的消息加密打包
/// </summary>
/// <param name="data">微信号待回复用户的消息，xml格式的字符串</param>
/// <param name="timestamp">时间戳，可以自己生成，也可以用URL参数的timestamp</param>
/// <param name="nonce">随机串，可以自己生成，也可以用URL参数的nonce</param>
/// <returns>加密后的可以直接回复用户的密文，包括msg_signature, timestamp, nonce, encrypt的xml格式的字符串</returns>
/// <exception cref="WeixinMessageCryptographicException">异常</exception>
public string Encrypt(string data, string timestamp, string nonce)
{
string result = "";
if (string.IsNullOrWhiteSpace(_options.EncodingAESKey))
{
return(data); //不加密，直接返回原文，以便支持微信开发者测试号
}
if (_options.EncodingAESKey?.Length != 43)
{
throw WeixinMessageEncryptorError.IllegalAesKey();
}
string raw = "";
try
{
raw = CryptographyHelper.AesEncrypt(data, _options.EncodingAESKey, _options.AppId);
}
catch (Exception ex)
{
throw WeixinMessageEncryptorError.AesEncryptFailed(ex);
}
string msg_signature = SignatureHelper.CalculateSignature(_options.WebsiteToken, timestamp, nonce, raw);
result = $"<xml><Encrypt><![CDATA[{raw}]]></Encrypt><MsgSignature><![CDATA[{msg_signature}]]></MsgSignature><TimeStamp><![CDATA[{timestamp}]]></TimeStamp><Nonce><![CDATA[{nonce}]]></Nonce></xml>";
return(result);
}
/// <summary>
/// 检验消息的真实性，并获取解密后的明文
/// </summary>
/// <param name="msg_signature">签名串，对应URL参数的msg_signature</param>
/// <param name="timestamp">时间戳，对应URL参数的timestamp</param>
/// <param name="nonce">随机串，对应URL参数的nonce</param>
/// <param name="data">密文，对应POST请求的数据</param>
/// <returns>解密后的原文</returns>
/// <exception cref="WeixinMessageCryptographicException">异常</exception>
public string Decrypt(string msg_signature, string timestamp, string nonce, string data)
{
string result = "";
if (_options.EncodingAESKey.Length != 43)
{
throw WeixinMessageEncryptorError.IllegalAesKey();
}
string encryptBody;
XmlDocument doc = new XmlDocument
{
XmlResolver = null
};
XmlNode root;
try
{
doc.LoadXml(data);
root = doc.FirstChild;
encryptBody = root["Encrypt"].InnerText;
}
catch (Exception ex)
{
throw WeixinMessageEncryptorError.ParseXmlFailed(ex);
}
if (!SignatureHelper.ValidateSignature(msg_signature, _options.WebsiteToken, timestamp, nonce, encryptBody))
{
throw WeixinMessageEncryptorError.CalculateSignatureFailed();
}
string appId = "";
try
{
result = CryptographyHelper.AesDecrypt(encryptBody, _options.EncodingAESKey, ref appId);
}
catch (FormatException ex)
{
throw WeixinMessageEncryptorError.DecodeBase64Failed(ex);
}
catch (Exception ex)
{
throw WeixinMessageEncryptorError.AesDecryptFailed(ex);
}
if (appId != _options.AppId)
{
throw WeixinMessageEncryptorError.ValidateAppidFailed();
}
return(result);
}