Azure Storage Account generate SAS Token, not an SAS URI

Question

I'm using the Azure.Storage.Blob library to generate a SasToken, but I get instead a Sas Uri. I looked for examples online and in the docs.

I tried to generate a token myself but I didn't succeed in doing so. I even tried creating a SharedKeyLite but that didn't work aswell.

My code for SharedKeyLite:

      var stringToSign = $"{DateTimeOffset.UtcNow.ToString("R", CultureInfo.InvariantCulture)}\n${canonicalizedResource}";
      var hmac = new HMACSHA256(Convert.FromBase64String(storageAccountKey));
      var hash = hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign));
      return Convert.ToBase64String(hash);

My request:

URI: https://<myAccount>.blob.core.windows.net/<pathToFile>

# Headers
Authorization: SharedKeyLite <myAccount>:<keyFromAbove>
x-ms-date: date
x-ms-version: 2014-02-14

Error:

Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature.

Why doesn't Azure.Storage.Blob generate a SAS Token?

Answer 1

Use the Azure CLI to get the SAS token from the Storage Account.

 az storage blob generate-sas \ --account-name {Storage Account name} \
--container-name {container name} \--name {blob name} \--permissions 
 {permissions to grant} \--expiry {datetime to expire the SAS token} \
--services {storage services the SAS allows} \--resource-types {resource types the SAS allows}

Example:

CONNECTION_STRING=<connection-string> az storage blob generate-sas \
    --account-name MyStorageAccount \ --container-name MyContainer \
   --name MyBlob \ --permissions racdw \ --expiry 2020-06-15

For more details refer this link

Another method to generate SAS Token

    private static string GetSharedAccessSignature(
           string accountName,
           string accountkey,
           string blobContainer,
           string blobName,
           DateTimeOffset sharedAccessStartTime,
           DateTimeOffset sharedAccessExpiryTime)
    {
        var canonicalNameFormat = $"/blob/{accountName}/{blobContainer}/{blobName}";
        var st = sharedAccessStartTime.UtcDateTime.ToString("yyyy-MM-ddTHH:mm:ssZ");
        var se = sharedAccessExpiryTime.UtcDateTime.ToString("yyyy-MM-ddTHH:mm:ssZ");
        var sasVersion = "2016-05-31";
    
        string stringToSign = string.Format("{0}\n{1}\n{2}\n{3}\n{4}\n{5}\n{6}\n{7}\n{8}\n{9}\n{10}\n{11}\n{12}", new object[]
        {
            "r",
            st,
            se,
            canonicalNameFormat,
            string.Empty,
            string.Empty,
            string.Empty,
            sasVersion,
            string.Empty,
            string.Empty,
            string.Empty,
            string.Empty,
            string.Empty
        });
    
        var sas = GetHash(stringToSign, accountkey);
    
        var credentials =
            $"?sv={sasVersion}&sr=b&sig={UrlEncoder.Default.Encode(sas)}&st={UrlEncoder.Default.Encode(st)}&se={UrlEncoder.Default.Encode(se)}&sp=r";
    
        string blobUri = $"https://{accountName}.blob.core.windows.net/{blobContainer}/{blobName}";
        return blobUri + credentials;
    }
    
    private static string GetHash(string stringToSign, string key)
    {
        byte[] keyValue = Convert.FromBase64String(key);
    
        using (HMACSHA256 hmac = new HMACSHA256(keyValue))
        {
            return Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
        }
    }

For more details refer this thread