public class AppBlobService
    private readonly string _connectionString;
    public AppBlobService(string connectionString)
        _connectionString = connectionString;
    public async Task<Uri?> CreateSasTokenUri(string containerName, string blobName)
        var blobServiceClient = new BlobServiceClient(_connectionString);
        var containerClient = blobServiceClient.GetBlobContainerClient(containerName);
        var blobClient = containerClient.GetBlobClient(blobName);
        Uri ret = null;
            if (await blobClient.ExistsAsync())
                ret = await GetUserDelegationSasBlob(blobClient);
        catch (Exception e)
            Console.WriteLine(e);
        return ret;
    private async Task<Uri> GetUserDelegationSasBlob(BlobClient blobClient)
        BlobServiceClient blobServiceClient =
            blobClient.GetParentBlobContainerClient().GetParentBlobServiceClient();
        Azure.Storage.Blobs.Models.UserDelegationKey userDelegationKey =
            await blobServiceClient.GetUserDelegationKeyAsync(DateTimeOffset.UtcNow,
                DateTimeOffset.UtcNow.AddDays(7));
        BlobSasBuilder sasBuilder = new BlobSasBuilder()
            BlobContainerName = blobClient.BlobContainerName,
            BlobName = blobClient.Name,
            Resource = "b",
            StartsOn = DateTimeOffset.UtcNow,
            ExpiresOn = DateTimeOffset.UtcNow.AddDays(7)
        sasBuilder.SetPermissions(BlobSasPermissions.Read );
        BlobUriBuilder blobUriBuilder = new BlobUriBuilder(blobClient.Uri)
            Sas = sasBuilder.ToSasQueryParameters(userDelegationKey,
                blobServiceClient.AccountName)
        return blobUriBuilder.ToUri();
    public async Task<BlobEntity> GetAsync(string containerName, string blobName)
        var ret = new BlobEntity(containerName, blobName);
        var blobServiceClient = new BlobServiceClient(_connectionString);
        var containerClient = blobServiceClient.GetBlobContainerClient(containerName);
        var blobClient = containerClient.GetBlobClient(blobName);
        if (await blobClient.ExistsAsync())
            var ms = new MemoryStream();
            await blobClient.DownloadToAsync(ms);