prf := hmac.New(sha256.New, s.key)
	prf.Write(iv)
	key := prf.Sum(make([]byte, 0, prf.Size()))

	block, err := aes.NewCipher(key)
	if err != nil {
		return DEK{}, err
	}
	aead, err := cipher.NewGCM(block)
	if err != nil {
		return DEK{}, err
	}

	plaintext, err := sioutil.Random(32)
	if err != nil {
		return DEK{}, err
	}
	ciphertext := aead.Seal(nil, nonce, plaintext, associatedData)

pkg container/list, method (*List) MoveAfter(*Element, *Element)
pkg container/list, method (*List) MoveBefore(*Element, *Element)
pkg crypto, type PublicKey interface {}
pkg crypto/cipher, func NewGCM(Block) (AEAD, error)
pkg crypto/cipher, type AEAD interface { NonceSize, Open, Overhead, Seal }
pkg crypto/cipher, type AEAD interface, NonceSize() int