Create Table in Azure using REST API

Question

Has anyone tried creating a table inside a storage account using REST API? I can do it without an issue if I use SharedKeyLite authorization. However, when using SharedKey authorization, the authentication keeps on failing.

My guess is it's got to do something with the "Content-MD5" value in the Authorization signature. The documentation is a little vague on Content-MD5 value and I can't find a recommended way to generate Content-MD5 in the documentation.

I can't find an example using C#. The only example I found was using Powershell and that is using an empty string for Content-MD5. However, that doesn't work for my case.

Here is my code:

public static void CreateTable(string storageAccount, string storageKey, string tableName)
        {
            var client = new HttpClient();

            string date = DateTime.UtcNow.ToString("R", System.Globalization.CultureInfo.InvariantCulture);
            client.DefaultRequestHeaders.Add("x-ms-date", date);
            string msVersion = "2018-03-28";
            client.DefaultRequestHeaders.Add("x-ms-version", msVersion);
            client.DefaultRequestHeaders.Add("MaxDataServiceVersion", "3.0;NetFx");
            client.DefaultRequestHeaders.Add("DataServiceVersion", "3.0;NetFx");
            client.DefaultRequestHeaders.Add("Accept", "application/json;odata=nometadata");
            string payload = "{ \"TableName\":\""+ tableName +"\" }";
            int contentLength = GetContentLength(payload);
            string authH = "SharedKey " + storageAccount + ":" + CreateTableSignature("POST", payload, "application/json", date, storageAccount + "/Tables", storageKey, new List<string>() { });
            client.DefaultRequestHeaders.Add("Authorization", authH);
            string requestUri = $"https://{storageAccount}.table.core.windows.net/Tables";

            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, requestUri);
            request.Content = new StringContent(payload,
                                                Encoding.UTF8,
                                                "application/json");
            request.Content.Headers.ContentLength = contentLength;
            client.SendAsync(request)
                  .ContinueWith(responseTask =>
                  {
                      Console.WriteLine("Response: {0}", responseTask.Result);
                  });
        }
public static string CreateTableSignature(string verb, string content, string contentType,  string date, string resource, string key, List<string> canonicalizedResourceParms)
        {
            string msgSignature = verb + "\n" +
               CreateMD5(content) + "\n" +
               contentType + "\n" +
               date + "\n";

            msgSignature += "/" + resource;
            foreach (string parm in canonicalizedResourceParms)
                msgSignature += "\n" + parm;
            byte[] SignatureBytes = Encoding.UTF8.GetBytes(msgSignature);

            // Create the HMACSHA256 version of the storage key.
            HMACSHA256 SHA256 = new HMACSHA256(Convert.FromBase64String(key));

            // Compute the hash of the SignatureBytes and convert it to a base64 string.
            return Convert.ToBase64String(SHA256.ComputeHash(SignatureBytes));

        }
public static string CreateMD5(string input)
        {
            // Use input string to calculate MD5 hash
            using (System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create())
            {
                byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input);
                byte[] hashBytes = md5.ComputeHash(inputBytes);
                return Convert.ToBase64String(hashBytes);
            }
        }

Answer 1

Two points to fix.

1. Content-Type

    request.Content = new StringContent(payload, Encoding.UTF8, "application/json"); 

   In this method, SDK actually sets application/json; charset=utf-8 application/json; charset=utf-8 when we sending the request. This means the signature needs application/json; charset=utf-8 application/json; charset=utf-8 as well.

   Or I recommend you to remove that misleading content type setting and use

    request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json"); 

2. Content-MD5

   It's not required in signature, you can leave it empty. Otherwise If you want to put it in the signature, you need to add corresponding request header first.

    request.Content.Headers.ContentMD5 = Convert.FromBase64String(CreateMD5(payload)); 

   Besides, in method CreateMD5(), Encoding should be UTF8

    System.Text.Encoding.UTF8.GetBytes(input);