func encryptWriterV20(dst io.Writer, config *Config) (*encWriterV20, error) {
	ae, err := newAuthEncV20(config)
	if err != nil {
		return nil, err
	}
	return &encWriterV20{
		authEncV20: ae,
		dst:        dst,
		buffer:     make(packageV20, maxPackageSize),
	}, nil
}
encryptWriterV20 returns an io.WriteCloser wrapping the given io.Writer.
The returned io.WriteCloser encrypts everything written to it using DARE 2.0
and writes all encrypted ciphertext as well as the package header and tag
to the wrapped io.Writer.

The io.WriteCloser must be closed to finalize the encryption successfully.
package sio
import (
	"io"
)
type encWriterV20 struct {
	authEncV20
	dst io.Writer
	buffer packageV20
	offset int
}