Process p = new Process();
p.StartInfo.UseShellExecute = false;
p.StartInfo.RedirectStandardOutput = true;
p.StartInfo.FileName = "openssl\\openssl.exe";
p.StartInfo.Arguments = "\"2010-05-18;2010-05-18T11:22:19;FAC 001/14;3.12; \" | openssl dgst -sha1 -sign prikeyofs.pem | openssl enc -base64";
p.Start();
string output = p.StandardOutput.ReadToEnd();
p.WaitForExit();