/// <summary>

    /// 使用微信支付平台证书公钥加密验签

    /// https://wechatpay-api.gitbook.io/wechatpay-api-v3/qian-ming-zhi-nan-1/qian-ming-yan-zheng

    /// </summary>

    public class WXPlatform

    {

        public string PublicKey { get; private set; }

        private byte[] _publicKeyBytes { get; set; }

        /// <summary>

        /// 构造方法

        /// </summary>

        /// <param name="publickey">-----BEGIN CERTIFICATE----- 开头的string，转为bytes->不需要每次都去</param>

        public WXPlatform(string publickey)

        {

            this.PublicKey = publickey;

            this._publicKeyBytes = Encoding.UTF8.GetBytes(publickey);

        }

        /// <summary>

        /// 最终提交请求时，需对敏感信息加密，如身份证、银行卡号。

        /// 加密算法是RSA，使用从接口下载到的公钥进行加密，非后台下载到的私钥。

        /// </summary>

        /// <param name="text">要加密的明文</param>

        /// <param name="publicKey">  </param>

        /// <returns></returns>

        public string Encrypt(string text)

        {

            var x509 = new X509Certificate2(this._publicKeyBytes);

            using (var rsa = (RSACryptoServiceProvider)x509.PublicKey.Key)

            {

                var buff = rsa.Encrypt(Encoding.UTF8.GetBytes(text), true);

                return Convert.ToBase64String(buff);

            }

        }

        /// <summary>

        /// 验证签名

        /// </summary>

        /// <param name="signedString">私钥加密串-Wechatpay-Signature</param>

        /// <param name="signSourceString">验签名串-应答时间戳\n应答随机串\n应答报文主体\n</param>

        /// <returns></returns>

        public bool VerifySign(string signedString, string signSourceString)

        {

            var x509 = new X509Certificate2(this._publicKeyBytes);

            using (var rsa = (RSACryptoServiceProvider)x509.PublicKey.Key)

            {

                using (var sha256 = new SHA256CryptoServiceProvider())

                {

                    var b = rsa.VerifyData(Encoding.UTF8.GetBytes(signSourceString), sha256, Convert.FromBase64String(signedString));

                    return b;

                }

            }

        }

    }