Problems with generating SAS manually for blob file - azure

Question

I'm trying to make a downloader attached to the service bus that is going to download the files from blob storage. But I'm having some problems with generating the SAS token manually, please se the error message below.
I'm getting error <AuthenticationErrorDetail>Signature fields not well formed.</AuthenticationErrorDetail>
private static string createToken(string resourceUri, string keyName, string key)
{
var now = DateTime.UtcNow;
TimeSpan sinceEpoch = now - new DateTime(1970, 1, 1);
var time = 60 * 2;
var expiry = Convert.ToString((int)sinceEpoch.TotalSeconds + time);
var expiryDateString = now.AddSeconds(time).ToUniversalTime().ToString("u");
string stringToSign = HttpUtility.UrlEncode(resourceUri) + "\n" + expiry;
HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key));
var signature = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
var sasToken = String.Format(
CultureInfo.InvariantCulture,
"{0}?sp={1}&st={2}&se={3}&spr={4}&sv={5}&sr={6}&sig={7}",
resourceUri,
"r",
DateTime.UtcNow.ToUniversalTime().ToString("u"),
expiryDateString,
"https",
"2019-02-02",
"b",
HttpUtility.UrlEncode(signature));
return sasToken;
}
Is it the stringToSign? Or signature as a whole? I'm a but unusre, to maybe I need to use the HttpUtility.UrlEncoder on all fields?

Answer 1

Please try the code below, it generates a working sas token for me:
static void Main(string[] args)
{
string resourceUri = "https://xx.blob.core.windows.net/test1/1.txt";
string account_name= "storage account name";
string key = "storage account key";
string s1 = createToken(resourceUri,account_name,key);
Console.WriteLine(s1);
Console.ReadLine();
}
private static string createToken(string resourceUri, string account_name, string key)
{
var accountName = account_name;
var accountKey = key;
var start = DateTime.UtcNow.AddHours(-2).ToString("yyyy-MM-ddTHH:mm:ssZ");
var end = DateTime.UtcNow.AddHours(2).ToString("yyyy-MM-ddTHH:mm:ssZ");
var permission = "rwdlac";
var serviceType = "b";
var resourceTypes = "sco";
var protocol = "https";
var serviceVersion = "2019-02-02";
//here is the difference from your code.
var stringToSign = string.Format("{0}\n{1}\n{2}\n{3}\n{4}\n{5}\n{6}\n{7}\n{8}\n",accountName, permission,serviceType,resourceTypes,start,end,"",protocol,serviceVersion);
HMACSHA256 hmac = new HMACSHA256(Convert.FromBase64String(accountKey));
string signature = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
var sasToken = string.Format("?sv={0}&ss={1}&srt={2}&sp={3}&se={4}&st={5}&spr={6}&sig={7}", serviceVersion,
serviceType, resourceTypes, permission, end, start, protocol, HttpUtility.UrlEncode(signature));
var urlToListTables = resourceUri + sasToken;
return urlToListTables;
}
Please let me know if you still have any issues.