如何从 c# 连接到 Apple News API？

Question

我正在尝试连接到 Apple 的新闻 API。生成签名时，每个不同示例的结果都相同。但是，我不断收到此错误：

 {"errors":[{"code":"WRONG_SIGNATURE"}]}

这是我生成身份验证标头的 c# 代码。

public class Security

{

  public static string AuthHeader(string method, string url, object content=null)

  {

    var apiKeyId = "<YOUR KEY HERE...>"; //we get this value from our settings file.

    var apiKeySecret = "<YOUR SECRET HERE...>"; //we get this value from our settings file.

    if ( string.IsNullOrEmpty(apiKeyId) || string.IsNullOrEmpty(apiKeySecret)) return string.Empty;

    var encoding = new ASCIIEncoding();

    var dt = DateTime.Now.ToString(Constants.DateFormat);

    var canonicalRequest = string.Format("{0}{1}{2}", method, url, dt);

    var key = Convert.FromBase64String(apiKeySecret);

    var hmac = new HMACSHA256(key);

    var hashed = hmac.ComputeHash(encoding.GetBytes(canonicalRequest));

    var signature = Convert.ToBase64String(hashed);

    var authorizaton = string.Format(@"HHMAC; key={0}; signature={1}; date={2}", apiKeyId, signature, dt);

    return authorizaton;

  }

}

常量类的简短版本

public static class Constants

{

  public static readonly string ChannelId = "<YOUR CHANNEL ID HERE...>"; //again from our settings file

  public static readonly string BaseUrl = "https://news-api.apple.com";

  public static readonly string DateFormat = "yyyy-MM-ddTHH:mm:ssK";    

}

Actions 类的简短版本（SendCommand 是执行请求的方法）

public class Actions

{

  public static string SendCommand(string action, string method)

  {

    var url = $"{Constants.BaseUrl}{action}";      

    var authheader = Security.AuthHeader(method, url, null);

    var request = (HttpWebRequest)WebRequest.Create(url);

    request.Method = method;

    request.Timeout = 1000;

    request.Headers.Add("Authorization", authheader);

    request.Accept = "application/json";

    request.ContentType = "application/json";

    var output = string.Empty;

我正在使用 ReadChannel 方法进行测试。

我也尝试过 php 和 ruby 中的示例，但没有成功。

任何想法如何正确地做到这一点？