func randomBytes(length int) (b []byte, err error) {
	b = make([]byte, length)
	_, err = io.ReadFull(rand.Reader, b)
	if err != nil {
		err = errors.New("captcha: error reading random source: " + err.Error())
	}
	return
}
// randomBytes returns a byte slice of the given length read from CSPRNG.
randomBytes returns a byte slice of the given length read from CSPRNG.
// randomBytes returns a byte slice of the given length read from CSPRNG .
func randomBytes(length int) (b []byte, err error) {
	b = make([]byte, length)
	_, err = io.ReadFull(rand.Reader, b)
	if err != nil {
		err = errors.New("captcha: error reading random source: " + err.Error())
	}
	return
}
func randomBytes ( length int ) ( b [ ] byte , err error ) { b = make ( [ ] byte , length ) _ , err = io . ReadFull ( rand . Reader , b ) if err != nil { err = errors . New ( " " + err . Error ( ) ) } return }
randomBytes returns a byte slice of the given length read from CSPRNG.
randomBytes returns a byte slice of the given length read from CSPRNG .