func NewMGM(cipher cipher.Block, tagSize int) (cipher.AEAD, error) {
blockSize := cipher.BlockSize()
if !(blockSize == 8 || blockSize == 16) {
func NewMGM(cipher cipher.Block, tagSize int) (cipher.AEAD, error) {
blockSize := cipher.BlockSize()
if !(blockSize == 8 || blockSize == 16) {