func encryptReaderV20(src io.Reader, config *Config) (*encReaderV20, error) {
	ae, err := newAuthEncV20(config)
	if err != nil {
		return nil, err
	}
	return &encReaderV20{
		authEncV20: ae,
		src:        src,
		buffer:     make(packageV20, maxPackageSize),
		firstRead:  true,
	}, nil
}
encryptReaderV20 returns an io.Reader wrapping the given io.Reader.
The returned io.Reader encrypts everything it reads using DARE 2.0.
package sio
import (
	"io"
)
type encReaderV20 struct {
	authEncV20
	src io.Reader
	buffer   packageV20
	offset   int
	lastByte byte
	firstRead bool
}