/// <returns>a signature of the original data followed by the data compressed with gzip.</returns>
private byte[] SignAndCompress(byte[] buffer)
{
using (var memory = new MemoryStream())
{
using (var gzip = new GZipStream(memory, CompressionMode.Compress))
{
gzip.Write(buffer, 0, buffer.Length);
}
return(_signing.GetSignature(buffer).Concat(memory.ToArray()).ToArray());
}
}