code: func (dig *PvtDataDigest) Hash() (string, error) {
  	b, err := proto.Marshal(dig)
  	if err != nil {
  		return "", err
  	}
  	return hex.EncodeToString(util.ComputeSHA256(b)), nil
  }
docs: // Hash returns the SHA256 representation of the PvtDataDigest's bytes