.Net Core微信服务商二次进件

最近商城进行微信服务商二次进件的开发，大致有几个点

一，服务商签名

二，服务商证书获取

三，图片上传

四，敏感信息加密

五，查询进件状态

除此之外，就是进件信息的拼装

电商二级商户进件申请单-状态流转

一 服务商签名

首先准备必须的配置：商户号、证书、秘钥、小程序appid、appsecret

        #region 服务商签名
        private string SrvPayBuildAuthAsync(string uri, string body, string method = "POST")
        {
            var timestamp = DateTimeOffset.Now.ToUnixTimeSeconds();
            string nonce = Guid.NewGuid().ToString();

            string message = $"{method}\n{uri}\n{timestamp}\n{nonce}\n{body}\n";
            string signature = SrvSign(message);

            return $"mchid=\"{_wxCfg.SrvPayMerchantId}\",nonce_str=\"{nonce}\",timestamp=\"{timestamp}\",serial_no=\"{_wxCfg.SrvPayCertNo}\",signature=\"{signature}\"";
        }

        private string SrvSign(string message)
        {
            var bytes = Utils.ReadBytesIfExist(_wxCfg.SrvPayCertFile);
            if (bytes is null)
            {
                return "";
            }
            X509Certificate2 cert = new(bytes, _wxCfg.SrvPayMerchantId);
            RSA rsa = cert.GetRSAPrivateKey();
            var signData = rsa.SignData(Encoding.UTF8.GetBytes(message), HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
            return Convert.ToBase64String(signData);
        }

二 获取证书

分为：第一步获取证书，第二步解密证书

1 获取证书

https://api.mch.weixin.qq.com/v3/certificates

        #region 获取平台证书
        public async Task<CertificatesOutModel> GetSrvCert()
        {
            string uri = "/v3/certificates";
            var auth = SrvPayBuildAuthAsync(uri, "", "GET");
            var header = new Dictionary<string, string>
            {
                { "Authorization",$"WECHATPAY2-SHA256-RSA2048 {auth}"},
                { "Accept","*/*" },
                { "Accept-Encoding","gzip,deflate,brn" },
                { "User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36 Edg/90.0.818.46" },
            };
            return await GetUrlAsync<CertificatesOutModel>(uri, header);
        }
        #endregion

使用的实体：CertificatesOutModel

    public sealed class CertificatesOutModel : IWXResponse
    {
        [JsonPropertyName("data")]
        public IEnumerable<Certificates> Data { get; set; }
        public string Code { get; set; }
        public string Message { get; set; }
    }
    public class Certificates
    {
        [JsonPropertyName("serial_no")]
        public string SerialNo { get; set; }

        [JsonPropertyName("effective_time")]
        public string EffectiveTime { get; set; }

        [JsonPropertyName("expire_time")]
        public string ExpireTime { get; set; }

        [JsonPropertyName("encrypt_certificate")]
        public EncryptCertificate EncryptCertificate { get; set; }
    }

请求方法：GetUrlAsync

 protected async Task<T> GetUrlAsync<T>(string url, Dictionary<string, string> headers = null)
        {
            HttpResponseMessage res = null;
            try
            {
                if (headers != null && headers.Count > 0)
                {
                    foreach (var header in headers)
                    {
                        _client.DefaultRequestHeaders.TryAddWithoutValidation(header.Key, header.Value);
                    }
                }
                res = await _client.GetAsync(url);
                res.EnsureSuccessStatusCode();
                var result = await res.Content.ReadAsStringAsync();
                if (result == null)
                {
                    return default;
                }

                return result.ToJson<T>();
            }
            catch
            {
                var result = await res.Content.ReadAsStringAsync();
                if (result == null)
                {
                    return default;
                }
                return result.ToJson<T>();
            }
        }

2，解密证书

            //获取证书
            var cert = await _wxClient.GetSrvCert();
            var certificateModel = cert.Data.FirstOrDefault();
            if (!cert.Data.Any())
            {
                return new MKResult<V3WXPayApplymentIdOutModel>(code: 400, msg: "未获取到平台证书");
            }
            if (!string.IsNullOrEmpty(applyment.Body.SerialNo))
            {
                certificateModel = cert.Data.SingleOrDefault(s => s.SerialNo == applyment.Body.SerialNo);
            }
            certificateModel.EncryptCertificate.Ciphertext = AESUtility.AesGcmDecrypt(
                      _wxCfg.SrvApiV3Key,
                      certificateModel.EncryptCertificate.AssociatedData,
                       certificateModel.EncryptCertificate.Nonce,
                      certificateModel.EncryptCertificate.Ciphertext
                   );

解密方法

 public class AESUtility
    {
        public static string AesGcmDecrypt(string key, string associatedData, string nonce, string ciphertext)
        {
            GcmBlockCipher gcmBlockCipher = new(new AesEngine());
            AeadParameters aeadParameters = new(
                new KeyParameter(Encoding.UTF8.GetBytes(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);
            gcmBlockCipher.DoFinal(plaintext, length);
            return Encoding.UTF8.GetString(plaintext);
        }
    }

三，上传图片

因为我的图片保存在oss，首先要网络图片Bytes，对图片进行sha256，方法在后面

        protected async Task<byte[]> GetUrlBytesAsync(string url, Dictionary<string, string> headers = null)
        {
            try
            {
                if (headers != null && headers.Count > 0)
                {
                    foreach (var header in headers)
                    {
                        _client.DefaultRequestHeaders.TryAddWithoutValidation(header.Key, header.Value);
                    }
                }

                var res = await _client.GetAsync(url);
                res.EnsureSuccessStatusCode();
                return await res.Content.ReadAsByteArrayAsync();
            }
            catch
            {
                return default;
            }
        }

然后上传图片

        /// <summary>
        /// 上传图片
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        public async Task<MKResult<V3WXPayFileUploadOutModel>> UploadFile(string url)
        {

            string fileContentType;
            string filetype;
            if (url!.Contains(".bmp", StringComparison.OrdinalIgnoreCase))
            {
                fileContentType = "image/bmp";
                filetype = ".bmp";
            }
            else if (url!.Contains(".jpg", StringComparison.OrdinalIgnoreCase))
            {
                fileContentType = "image/jpeg";
                filetype = ".jpg";
            }
            else if (url!.Contains(".jpeg", StringComparison.OrdinalIgnoreCase))
            {
                fileContentType = "image/jpeg";
                filetype = ".jpeg";
            }
            else
            {
                fileContentType = "image/png";
                filetype = ".png";
            }

            UploadMerchantMediaImageRequest meta = new();
            var fileBytes = await GetUrlBytesAsync(url);//获取网络图片Bytes
            if ((fileBytes?.Length ?? 0) == 0)
            {
                return new MKResult<V3WXPayFileUploadOutModel>(code: 400, msg: "转换图片失败");
            }
            meta.FileHash = GetHash(fileBytes);
            meta.FileName = Guid.NewGuid().ToString("N").ToLower() + filetype;

            string boundary = "--BOUNDARY--" + DateTimeOffset.Now.Ticks.ToString("x");
            using var fileContent = new ByteArrayContent(fileBytes);
            using var metaContent = new StringContent(meta.ToJson(), Encoding.UTF8, "application/json");
            using var httpContent = new MultipartFormDataContent(boundary);
            httpContent.Add(metaContent, "\"meta\"");//meta 必须要加双引号
            httpContent.Add(fileContent, "\"file\"", "\"" + meta.FileName + "\"");//必须要加双引号
            httpContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data; boundary=" + boundary);// boundary不能加引号
            metaContent.Headers.ContentType = MediaTypeHeaderValue.Parse("application/json");
            fileContent.Headers.ContentType = MediaTypeHeaderValue.Parse(fileContentType);

            var uri = $"/v3/merchant/media/upload";
            var res = await V3UpLoadFile<V3WXPayFileUploadOutModel>(uri, meta.ToJson(), httpContent);
            return new MKResult<V3WXPayFileUploadOutModel>(res, 1);
        }

  private async Task<T> V3UpLoadFile<T>(string uri, string meta, MultipartFormDataContent content)
        {
            var auth = SrvPayBuildAuthAsync(uri, meta);
            var header = new Dictionary<string, string>
            {
                { "Authorization",$"WECHATPAY2-SHA256-RSA2048 {auth}"},
                { "Accept","*/*" },
                { "Accept-Encoding","gzip,deflate,brn" },
                { "User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36 Edg/90.0.818.46" },
            };
            return await V3PostFileAsync<T>(uri, header, content);
        }

 protected async Task<T> V3PostFileAsync<T>(string url, Dictionary<string, string> headers, MultipartFormDataContent content)
        {
            HttpResponseMessage res = null;
            try
            {
                if (headers != null && headers.Count > 0)
                {
                    foreach (var header in headers)
                    {
                        _client.DefaultRequestHeaders.TryAddWithoutValidation(header.Key, header.Value);
                    }
                }
                res = await _client.PostAsync(url, content);
                res.EnsureSuccessStatusCode();
                var result = await res.Content.ReadAsStringAsync();
                if (result == null)
                {
                    return default;
                }
                return result.ToJson<T>();
            }
            catch
            {
                var result = await res.Content.ReadAsStringAsync();
                if (result == null)
                {
                    return default;
                }
                return result.ToJson<T>();
            }
            finally
            {
                if (content != null)
                {
                    content.Dispose();
                }
            }
        }

   #region 二进制内容进行sha256
        private static string GetHash(byte[] bytes)
        {
            if (bytes == null) throw new ArgumentNullException(nameof(bytes));

            using SHA256 sha = SHA256.Create();
            byte[] hashBytes = sha.ComputeHash(bytes);
            return BitConverter.ToString(hashBytes).Replace("-", "").ToLower();
        }

四，敏感信息加密

使用获取到的证书certificateModel，进行加密

    public static class RSAUtility
    {
        public static string RSAEncrypt(string text, Certificates certificateModel)
        {
            var bytes = Encoding.UTF8.GetBytes(certificateModel.EncryptCertificate.Ciphertext);
            using var x509 = new X509Certificate2(bytes);
            var rsaParam = x509.GetRSAPublicKey().ExportParameters(false);
            var rsa = new RSACryptoServiceProvider();
            rsa.ImportParameters(rsaParam);
            var buff = rsa.Encrypt(Encoding.UTF8.GetBytes(text), true);
            return Convert.ToBase64String(buff);
        }

    }

五，查询进件状态

直接使用进件返回的Id,调用接口查询就Ok了