/// <summary>
/// Computes a SHA1 hash for provided image transformation parameters.
/// </summary>
/// <param name="privateKey">Private key received from the image service administrator.</param>
/// <param name="width">Image width.</param>
/// <param name="height">Image height.</param>
/// <param name="transform">Image transformation mode.</param>
public string ComputeHash(string privateKey, int width, int height, ImageTransform transform)
{
var values = new[]
{
privateKey.ToLower(),
width.ToString(),
height.ToString(),
transform.ToString().ToLower()
};
var bytes = Encoding.ASCII.GetBytes(string.Join(":", values));
var sha1 = SHA1.Create();
sha1.ComputeHash(bytes);
return BitConverter.ToString(sha1.Hash).Replace("-", "").ToLower();
}
