You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: encryption.go
    path of file: ./repos/podman/vendor/github.com/containers/luksy
    
    the code of the file until where you have to start completion: package luksy

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"crypto/sha1"
	"crypto/sha256"
	"crypto/sha512"
	"encoding/binary"
	"errors"
	"fmt"
	"hash"
	"io"
	"strings"

	"github.com/aead/serpent"
	"golang.org/x/crypto/cast5"
	"golang.org/x/crypto/ripemd160"
	"golang.org/x/crypto/twofish"
	"golang.org/x/crypto/xts"
)

fu
    
func v2decrypt(cipherSuite string, ivTweak int, key []byte, ciphertext []byte, sectorSize int, bulk bool) ([]byte, error) {
	var cipherName, cipherMode string
	switch {
	default:
		cipherSpec := strings.SplitN(cipherSuite, "-", 2)
		if len(cipherSpec) < 2 {
			return nil, fmt.Errorf("unrecognized cipher suite %q", cipherSuite)
		}
		cipherName = cipherSpec[0]
		cipherMode = cipherSpec[1]
	}
	return v1decrypt(cipherName, cipherMode, ivTweak, key, ciphertext, sectorSize, bulk)
}