using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
            {
                using (SHA256CryptoServiceProvider sha = new SHA256CryptoServiceProvider())
                {
                    byte[] data = Encoding.UTF8.GetBytes(textBoxOriginalMessage.Text);
                    byte[] hash = sha.ComputeHash(data);

                    byte[] signature = rsa.SignHash(hash, CryptoConfig.MapNameToOID("SHA256"));

                    textBoxDigitalSignature.Text = BitConverter.ToString(signature);
                    textBoxDigitalSignatureBits.Text = (signature.Length * 8).ToString();
                    textBoxMessageDigest.Text = BitConverter.ToString(hash);
                    textBoxMessageDigestBits.Text = (hash.Length * 8).ToString();
                }
            }