func getReqSigDataHash(req *msg.OcReq) ([]byte, error) { var buf bytes.Buffer req.WriteSignablePortion(&buf) hasher := sha256.New() _, err := hasher.Write(buf.Bytes()) if err != nil { return nil, fmt.Errorf("error while hashing: %v", err.Error()) } h := hasher.Sum([]byte{}) return h, nil }