code: func GenerateSignature(priv *rsa.PrivateKey, data string) (enc []byte, err error) {
  	sig, err := privateEncrypt(priv, []byte(data))
  	if err != nil {
  		return nil, err
  	}
  
  	return sig, nil
  }
docs: // GenerateSignature will generate a signature ( sign ) the given data